B-44 Geology of Silver Reef [Harrisburg] Mining District Washington County, Utah

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UTAH GEOLOGICAL AND MINERALOGICAL SURVEY

AFFILIATED WITH

THE COLLEGE OF MINES AND MINERAL INDUSTRIES

UNIVERSITY 0 F UTAH

SALT LAKE CITY, UTAH

GEOLOGY OF THE SILVER REEF

(HARRISBURG) MINING DISTRICT

WASHINGTON COUNTY

UTAH

By

PAUL DEAN PROCTOR

Bulletin 44 April 1953

Price $2.00



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; - , ' "



CONTENTS

ILLUSTRATIONS. •

TABLES • • • • .FIGURES. • • • • •FOREWORD •

Pagev i

v iv i i

• • v i i iABSTRACT • • • • • . . . . 1

INTRODUCTION •PREVIOUS WORK.

FIELD WORK • •ACKNOWLEDGEMENTS •LOCATION • . • • • •

. • . • 4

SURFACE FEATURES . • . • .GEOLOGIC SETTING • •

SEDIMENTARY ROCKS. • . • •

Moenkopi Format ionShinarump Conglomera te •

Chin le Format ion . . • • .

Loyer C h i n l e member . •

. ...

H a r t l e y s h a l e s and s a n d s t o n e s • .

F i r e Clay H i l l b e n t o n i t i c s h a l e s • .

T r a i l H i l l s a n d s t o n e. . .

S i l v e r Reef s a n d s t o n e member • • • • •

Leeds s a n d s t o n e . • .

Tecumseh s a n d s t o n e • . • . • . • • •

D e p o s i t i o n a l h i s t o r y of S . R . s s .Stream d i r e c t i o n s • •

D u ff i n s a n d s t o n e and s h a l e s .Navajo Sands tone • • .

Quate rna ry Al luv ium. •

Boulde r a l luv iumRecent a l l u v i u m .

IGNEOUS ROCKS. • . •

B a s a l t F l o y s • • •

STRUCTURAL SETTING OF THE DISTRICT .F o l d s . . . . . . . . . . . . .

Vi rg i n a n t i c l i n e •

Leeds a n t i c l i n e .Leeds s y n c l i n e • . . • • .

J o i n t s • • • • . • • . •

White Reef . •

Buckeye Reef .

B u t t e ReefE a s t Reef .O r i g i n . •

- i i i -

4567

81212121416181919

222325282935363839

394142424444444547

47

4848494949



F a u l t s • • • • • • • .

Page50

Normal f a u l t s . . . . . . . . . . . 51

White Reef • • • •

Buckeye R e e f . • • • • • . •

Vi rg i n a n t i c l i n e nose . . •E a s t Reef • • • • • • . . • • •

T h r u s t f a u l t s • • . • . • • • • •

T h r u s t s o u t h e a s t o f Savage s h a f t .Age of f a u l t s . . • • .

ECONOMIC GEOLOGY • • . . . • • .HISTORY • • • • • . . • .

P r o d u c t i o n . • • •MINERAL DEPOSITS. • • .

G e n e r a l c h a r a c t e r o f t h e ~ d e p o s i t sWhi t e Reef d e p o s i t s . . • . .

S i l v e r . • • • . • .Copper • • • . • •

Uranium-vanadium.

51525455566565686875787882828485

Buckeye Reef . . • . • . 85S i l v e r . • . • • •

Copper. • • • . • .Uranium-vanadium.

B u t t e Reef • • • • . • • •

S i l v e r • • • • • • •

Copper. • • • • • .Uranium-vanad ium.

E a s t Reef • • • . • . • •

858992949495959595i l v e r • • . • . •

S t r u c t u r a l R e l a t i o n s h i p s ofChanne l s t r u c t u r e s .M i n e r a l ~ 7 a t i o n

9696F o l d s • • • • . . •J o i n t s . • • . . . .

• • • • 97

F a u l t s and s h e a r s . • • . • • .

Chemical R e l a t i o n s h i p s of M i n e r a l i z a t i o n .R e l a t i o n of S i l v e r , Coppe r, and Uran

ium t o Carbon ized S u b s t a n c e s • .R e l a t i o n of S i l v e r C o n t e n t t o Carbon-

9899

101

101

a t e C o n t e n t . . • . . . • • . • . 101R e l a t i o n of S i l v e r t o Copper Conten t . • 102R e l a t i o n of S i l v e r Conten t t o R a d i o -

A c t i v e M i n e r a l s • . . . • • . • . 102R e l a t i o n o f R a d i o - A c t i v e M i n e r a l s t o

Copper, Vanadium, and Selenium . 103



PageMI NERALOGY • • . • • • . • . • . . • 105

C e r a r g y r i t e . 105Emboli t e . . . . . 106Nat ive S i l v e r . • . • • . . . 106S i l v e r S e l e n i d e ( ? ) . • • • • • . • 107

A r g e n t i t e ( ? ) . . • • • • 107M a l a c h i t e . . . • . . • . . 108A z u r i t e . . . . . . . . • . . . . 109C u p r i t e . . • • • . . . 109Te n o r i t e . • 109C h a l c o c i t e . . • . • . • 109C h a l c o p y r i t e and B o r n i t e . • . . . . . 112P y r i t e • . . . . . . 112C a r n o t i t e . • . . . . . • 113

Autun i t e • . . • . . • . 113Vo l b o r t h i t e . . . • • . . 115Gangue M i n e r a l s . • • • • . • . • 116Muscovi te . . . • . . • . . 119K a o l i n i t e ( ? ) . • • • • • 119C a l c i t e . . . • . . 119Gypsum . . . • . . 119J a s p e r • • . . . . 120H a l i t e . . • . . . 120

Montmor i l l on i t e . . . . . . • 120A p a t i t e , Zi rcon , and Tourma l ine . • 120

GENESI S. . . . . . • . . • . . . 121Summary. . . . . . . . . . . . . . 141

THE MINES. • . . • • . • 143BIBLIOGRAPHY . . . 158INDEX. . . . . . . . . . . 164

GUIDEBOOKS . . . • . . . . . . . . . 170BULLETINS. • . 171

R e p r i n t s . . . • . . . 172M i s c e l l a n e o u s o t h e r l i t e r a t u r e . . 173

- v -



P l a t e

1 .

I I .

I I I .

IV.V.VI.

V I I .V I I I .

IX.X.

XI.

Ta b l e

1 .

2 .

3.

4.

5.

6.7.

8.

ILLUSTRATIONS

G e o l o g i c map or H a r r i s b u r g ( S i l v e rReef ) d i s t r i c t , Wash ing ton Coun ty,Utah . . . . . . · · · · · · · · ·

egend r o r P l a t e I · · · · · · · · ·e o l o g i c map or S i l v e r R e e f Min inga r e a , Wash ing ton Coun ty, U t a h . · ·

ypes or c r o s s - b e d d i n g · · · · · · ·ypes

orc r o s s - b e d d i n g · · · · · · ·e d i m e n t a r y r o c k t y p e s · · · · ·

e d i m e n t a r y r o c k t y p e s · · · · · · ·h r u s t f a u l t s . . . · · · · · · · · ·e r t i c a l s h e a r zone and r u i n s . · · ·

hotomicrographs of minera l occur rences .Photomicrographs of minera l occur rences .Drawings o f p h o t o m i c r o g r a p h s · · · ·

TABLES

Monthly r a i n f a l l a v e r a g e . • . . • • .Assay r e p o r t on c o n c r e t i o n s from F i r e

Clay H i l l b e n t o n i t i c s h a l e s • • • •

Assay r e p o r t on F i r e Clay H i l l b e n t o ni t i c s h a l e s , S i l v e r R e e f , Utah . • •

M i n e r a l o g i c a l a n a l y s i s o f Tecumsehs a n d s t o n e • • • • • • . • • •

M i n e r a l o g i c a l a n a l y s i s o f Leeds s a n d -s t o n e . . . . . . . . . . . . . . .

Ore m i n e r a l s a t S i l v e r R e e f , Utah • •

Minor C o n s t i t u e n t s o f T u f f , L y s i t e ,

Page

23

1026

2730315758

110I I I

114

Page

7

20

21

117

118129

Wyoming • • . • • • • • • . • . . . 141Av a i l a b l e h i s t o r y and p r o d u c t i o n o f

major companies a t S i l v e r Reef , Utah,1877-1882 • • • . • • . • . • • . •

Same: 1883-1888 • . . . . . . • . . .

i

154155



FIGURES

F i g u r e Page

1 . Measured s e c t i o n s o f C h i n l e f o r m a -t i o n • • • . . • . • • 17

2 . D i a g r a m m a t i c s e c t i o n a l o n g T r a i l

H i l l f a u l t . . • • 533. G e n e r a l i z e d f l o y s h e e t of S to rmon t

M i l l , S i l v e r R e e f , U t a h . • • • 724. Produc t ion c h a r t , S i l v e r Reef , Utah ,

1 8 7 7 - 1 9 1 0 . • • • 765. R e l a t i v e amounts o f coppe r and s i l -

v e r t o c a r b o n a t e c o n t e n t of S i l v e rReef sands tone . 90

6. R e l a t i v e c o p p e r - s i l v e r r a t i o s , White

and Buckeye Reefs • . 917 . Smal l f a u l t s , Buckeye and Las t Chance

M i n e s . • • • . • . • • 1008 . U r a n i u m - v a n a d i u m - c o p p e r - s i l v e r

s e l e n i u m r a t i o s . . . . . . . • 1049 . Pa ten ted c l a ims (1948) i n th e Leeds ,

Utah a r e a . • • . . • • . 14510 . P a t e n t e d c l a i m s (1948) i n th e E a s t

Reef a r e a , s o u t h e a s t of Leeds , Utah 1461 1 . Knoyn u n d e rg r o u n d y o r k i n g s i n t h e

S o u t h Thompson-Cobb-Nicho ls minea r e a . 149

1 2 . Knoyn u n d e rg r o u n d y o r k i n g s i n t h eL e e d s - C a l i f o r n i a - S a v a g e mine areas 150

1 3 . Knoyn u n d e rg r o u n d w o r k i n g s i n t h eTecumseh mine a r e a . . . . 152

- v i i -



FOREWORD

With t h e e s t a b l i s h m e n t of t h e Utah G e o l o g ic a l and M i n e r a l o g i c a l S u r v e y, i t was a t once e v id e n t t h a t n e i t h e r f u n d s , p e r s o n n e l , n or f a c i l i t i e swere a v a i l a b l e t o b e g i n a f u l l - f l e d g e d G e o l o g i c a land M i n e r a l o g i c a l S u r v e y o f t h e S t a t e on an i nd e p e n d e n t b a s i s . However, th e law u n d e r which i t

was f o u n d e d a u t h o r i z e d t h e S u r v e y t o c o o p e r a t ew i t h any and a l l e x i s t i n g a g e n c i e s whose a c t i v it i e s m i g h t c o n t r i b u t e t o i t s p r o g r a m . As a c o n -

s e q u e n c e , i m m e d i a t e s t e p s w e r e t a k e n t o e n l i s tt h e s u p p o r t o f a g e n c i e s and i n d i v i d u a l s who m i g h tbe i n t e r e s t e d i n t h i s t y p e o f c o o p e r a t i o n . Ob-v i o u s l y , t h e r e s e a r c h o f g r a d u a t e s t u d e n t s d o i n gt h e s i s work on p r o b l e m s i n Utah o f f e r e d t h e mos ti m m e d i a t e p r o m i s e f o r f r u i t f u l p a r t i c i p a t i o n .

The a u t h o r o f t h i s B u l l e t i n was one o f t h ef i r s t s u c h g r a d u a t e s t u d e n t s t o e n t e r i n t o a c o n -

t r a c t w i t h t h e S u r v e y t o c a r r y o u t s p e c i f i c r es e a r c h of mu tua l i n t e r e s t . P a u l Dean P r o c t o r , t hena c a n d i d a t e f o r t h e Ph.D. d e g r e e a t I n d i a n a U n i v -e r s i t y , was g r a n t e d a l i m i t e d s u b s i d y f o r c e r t a i ns p e c i f i e d p u r p o s e s w i t h a view t o e n r i c h i n g t h ec o n t e n t o f h i s m a n u s c r i p t f o r t h e p r o d u c t i o n o f a

b u l l e t i n m e e t i n g S u r v e y s t a n d a r d s . H is a r e a f o rs t u d y had a l r e a d y been s e l e c t e d by P r o c t o r i n c o n -s u l t a t i o n w i t h Dr. C h a r l e s F. D e i s s , Chai rman o f

t h e Depar tment o f Geology, I n d i a n a U n i v e r s i t y , andw i t h Dr. Eugene C a l l a g h a n , P r o f e s s o r o f EconomicGeology a t t h a t i n s t i t u t i o n .

Because o f i t s h i s t o r i c s i g n i f i c a n c e i n orogene-s i s and b e c a u s e o f i t s s t r a t e g i c p o s i t i o n a t t h eb o u n d a r y l i n e o f t h e C o l o r a d o P l a t e a u w i t h t h eB a s i n and Range P r o v i n c e as t h e s e p r o v i n c e s a r ee x h i b i t e d i n S o u t h e r n U t a h , t h e S i l v e r Reef d i st r i c t was g i v e n p r i o r i t y by t h e S u r v e y as a s u bj e c t Df s t u d y. While i t was u n d e r t a k e n p r i m a r i l yas a means o f t h r o w i n g a d d i t i o n a l l i g h t , by t h ea p p l i c a t i o n o f modern means o f r e s e a r c h , on t h eh i s t o r i c prob lem o f t h e f o r m a t i o n of economic d ep o s i t s o f s i l v e r i n s a n d s t o n e t h e p r e s e n c e o f

v i i i



s m a l l amoun t s o f u r a n i u m , vanad ium and s e l e n i u mi n t h e m i n e r a l a s s e m b l a g e m a k i n g u p t h e S i l v e rR e e f o r e b o d i e s was an i n t r i g u i n g a s p e c t o f t h es u b j e c t , and t h e f a c t t h a t t h e S i l v e r R e e f d i s -t r i c t was s i t u a t e d on wha t was b e l i e v e d t o be a

p o s s i b l e o i l s t r u c t u r e f u r n i s h e d an a d d i t i o n a lr e a s o n f o r g i v i n g p r e f e r e n c e t o t h i s i n v e s t i g a t i o n .

The c o n t r a c t w i t h , P r o c t o r was w r i t t e n w h i l et h e Utah G e o l o g i c a l and M i n e r a l o g i c a l S u r v e y wasy e t a s u b s e c t i o n of t h e Raw M a t e r i a l s D i v i s i o n o ft h e Utah S t a t e Depa r tmen t o f P u b l i c i t y and I n d u s -t r i a l Deve lopment .

The f i n a l p u b l i c a t i o n o f t h e w o r k h a s b e e nd e l a y e d f o r a n u m b e r o f r e a s o n s , c h i e f o f whichwas t h e d i s c o n t i n u a n c e o f t h e U . P. I . D . , t h e t r a n s -f e r o f t h e Utah G e o l o g i c a l and M i n e r a l o g i c a l S u r -vey t o t h e Col l ege o f Mines and M i n e r a l I n d u s t r i e s ,U n i v e r s i t y of Utah ( w i t h a d e c r e a s e d a p p r o p r i a t i o n )and t h e c o n s e q u e n t c u r t a i l m e n t i n f u n d s and p e r -s o n n e l t o p r o c e s s t h i s and o t h e r r e s e a r c h p a p e r sr e s u l t i n g f rom t h e s e c o o p e r a t i v e c o n t r a c t s . I nt h e m e a n t i m e , P r o c t o r c o m p l e t e d h i s r e q u i r e m e n t sand was awarded h i s d o c t o r a t e d e g r e e f rom I n d i a n aU n i v e r s i t y . H is work was r e c e i v e d w i t h s u c h a p -p r o v a l t h a t he was made A s s o c i a t e P r o f e s s o r o fGeo logy a t I n d i a n a U n i v e r s i t y wher e he r e m a i n e du n t i l t h e F a l l Q u a r t e r o f 1 9 5 2 , when he r e t u r n e dt o t h e B r i g h a m Young U n i v e r s i t y a s a p e r m a n e n tmember on th e g e o l o g i c a l f a c u l t y of t h a t i n s t i t u t i o n .

The prob lem o f t h e g e n e s i s o f t h e S i l v e r Reefo r e b o d i e s i s one w h i c h h a s r e c e i v e d t h e c l o s ea t t e n t i o n o f s t u d e n t s o f economic geo logy t h r o u g h -o u t t h e w o r l d . T h e s e o re b o d i e s c o n s t i t u t e t h eonly occurrence of i t s s i ze o f s i l v e r i n sands tone u n -c o n n e c t e d i n any d e m o n s t r a b l e way w i t h an i g n e o u ssou rce . I t w i l l be noted from t he fo l l owing B u l l e t i nt h a t Dr. Proc to r comes t o th e conc lu s ion , a f t e r weigh-in g a l l th e ev idence from h i s own and f rom p r e v i o u si n v e s t i g a t i o n s , t h a t t h e s i l v e r was d e r i v e d f romp a r t i c l e s o r i g i n a l l y d i s s e m i n a t e d i n v o l c a n i c a s h .He t h i n k s t h a t t h e s e were i n t u r n c o n c e n t r a t e d bys o l u t i o n an d r e p r e c i p i t a t e d by o r g a n i c m a t t e r

- i x -



a l o n g s t r e a m c h a n n e l s o f t h e Buckeye R e e f memberof t h e Chin le f o r m a t i o n . However, t o some of t h o s ef a m i l i a r w i t h t h e w i d e - s p r e a d o c c u r r e n c e o f t h eChin le b e n t o n i t i c members assumed t o have come fromv o l c a n i c a s h , i t may be d i f f i c u l t t o v i s u a l i z e th emechanism by which t h e s i l v e r i s assumed t o haveb e e n c o n c e n t r a t e d i n t o an economic d e p o s i t i n th eS i l v e r Reef a r e a w h i l e n o t r e c e i v i n g s i m i l a r c o n -c e n t r a t i o n i n any o f t h e many a r e a s t o th e e a s t o ft h e S i l v e r R e e f d i s t r i c t where t h e s e same C h i n l eb e d s a r e w e l l e x p o s e d .

A n o t h e r c i r c u m s t a n c e which may have g r e a t e rs i g n i f i c a n c e t h a n i s obv ious from P r o c t o r ' s t r e a tment i s th e a p p a r e n t c o r r e l a t i o n be tween th e s t r u ct u r e of t h e a r e a and th e S i l v e r Reef ore d e p o s i t s .I t a p p e a r s t h a t t h e economic d e p o i i t s fo rm a U-shaped o u t l i n e around t h e nose o f t h e Leeds a n t ic l i n e . Thi s would seem t o s u g g e s t t h a t t h e f o l d i n gp r e c e d e d t h e e m p l a c e m e n t o f t h e m i n e r a l s s o a st o have i n f l u e n c e d t h e i r mechanism of accumula t ion .

One wonder s i f t h e r e may n o t have b e e n some c o n -n e c t i o n b e t w e e n t h e g r e a t a n d e s i t i c a c c u m u l a t i o n si n Pine Va l l e y Mountain t o th e n o r t h and th e h y d r o -t h e r m a l s o l u t i o n s which c o n c e i v a b l y t r a v e l e d s o u t hward and u p w a r d on t h e Leeds a n t i c l i n e becomingc o l d e r i n t h e i r l o n g t r a n s i t t h r o u g h t h e p o r o u ss a n d s t o n e s , which a c t e d as c o n d u i t s , u n t i l t h e y nol o n g e r c o u l d r e t a i n i n s o l u t i o n t h e i r m e t a l l i cb u r d e n .

No d o u b t D r. P r o c t o r h as c o n s i d e r e d and d i sc o u n t e d i n h i s own mind t h e s e seeming imped imen t st o h i s t h e o r y . T h i s p a i n s t a k i n g r e v i e w o f t h el i t e r a t u r e and o f t h e c o n t r i b u t i o n s P r o c t o r h a smade f rom h i s own s t u d i e s w i l l be welcomed by r es e a r c h e r s i n t h i s f i e l d . In s p i t e o f a l l th e workt h a t h a s b e e n done on t h e S i l v e r Reef m i n e r a l o c -c u r r e n c e , i t s t i l l r e m a i n s as one o f t h e en igmaso f m i n e r a l g e n e s i s .

Ar thu r L. Crawford , Direc to rUtah Geolog ica l and Minera log ica l Survey

x



G E O L O G Y OF T H E S I L V E R

(HARRISBURG) MINING DISTRICT

WASHINGTON COUNTY

UTAH

BY

P a u l Dean P r o c t o r *

ABSTRACT

R E E F

The S i l v e r Reef min ing a r e a i n s o u t h w e s t e r nUtah c o n t a i n s t h e o n l y known o c c u r r e n c e i n t h eU n i t e d S t a t e s o f c o m m e r c i a l b o d i e s o f s i l v e r o re

w i t h m i n o r c o p p e r - u r a n i u m - v a n a d i u m m i n e r a l s i ns a n d s t o n e . The o re b o d i e s a r e r e s t r i c t e d t o t h eS i l v e r Reef s a n d s t o n e member of t h e u p p e r T r i a ss i c C h i n l e f o r m a t i o n and o c c u r on t h e l i m b s andnose o f a m a j o r a n t i c l i n e and a s u b s i d i a r y a n t ic l i n e and s y n c l i n e . A n e w l y r e c o g n i z e d n o r t ht r e n d i n g n o r m a l f a u l t and a t h r u s t f a u l t w i t h aminimum e a s t w a r d d i s p l a c e m e n t o f 1500 f e e t r ep e a t t h e o re h o r i z o n t h r e e t i m e s . No c o n s t a n tr e l a t i o n s h i p e x i s t s between th e m i n e r a l i z a t i o n andt h e f o l d s or f a u l t s .

S i l v e r , c o p p e r , and m i n o r g o l d v a l u e s i n ab e n t o n i t e 300 f e e t be low t h e o r e - b e a r i n g h o r i z o n ,m i n e r a l s of t h e s e m e t a l s and l e n s e - l i k e b e n t o n i t i cs h a l e s i n t h e S i l v e r R e e f s a n d s t o n e , and o t h e rknown o c c u r r e n c e s o f n o t a b l e m e t a l c o n t e n t i n v o lc a n i c t u f f s s u g g e s t a new t h e o r y o f o r i g i n f o rt h e s e u n u s u a l d e p o s i t s . I t i s c o n c l u d e d t h a t t h em e t a l s were p r i m a r y c o n s t i t u e n t s o f o r i g i n a l v o lc a n i c t u f f s i n T r i a s s i c t i m e ; t h a t t h e s e m e t a l swere d i s s o l v e d a n d / o r m e c h a n i c a l l y t r a n s p o r t e d bys t r e a m s e r o d i n g t h e t u f f a c e o u s s e d i m e n t s ; t h a tt h e y were l a t e r d e p o s i t e d w i t h t h e s a n d s t o n e ands h a l e s of t h e S i l v e r Reef a r e a ; t h a t f u r t h e r c o n -c e n t r a t i o n of t h e m e t a l s i n th e S i l v e r Reef s a n d -s t o n e was by (1 ) s o l u t i o n i n c i r c u l a t i n g groundw a t e r , and (2 ) p r e c i p i t a t i o n t h r o u g h c o n t a c t wi then tombed p l a n t d e b r i s and a s s o c i a t e d b a c t e r i a i nmore p e r m e a b l e b u r i e d T r i a s s i c s t r e a m c h a n n e l s .F o l d i n g , e r o s i o n , and e x p o s u r e of t h e o re h o r i z o ni s assumed t o have r e s u l t e d i n s e c o n d a r y e n r i c h

ment of t h e o re d e p o s i t s by m e t e o r i c w a t e r s .

*Former ly A s s o c i a t e P r o f e s s o r o f Geology, I n d i a n aU n i v e r s i t y , now A s s o c i a t e P r o f e s s o r o f Geology,Brigham Young U n i v e r s i t y .

- I -



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k " M A P A R E A

•INDEX MAP OF UTAH

N

P I a t e I . GEOLOGIC MAP OF HARRISBURG (SILVER REEF) DISTRICT,

WASHINGTON COUNTY, UTAH

2



EXPLANATION

SEDIMENTARY ROCKS

t i { 9 ~ l t t MALLUVIUM

~ ~NAVAJO SANDSTONE

"

..."

.. ,"~ ~ : R c l ~ ~ ~" ' , " " "

CHINLE FORMATION

(7?cu, UPPER CHINLE; u

7?Sr, SILVER REEF;inCf)

7?cl, LOWER CHINLE) ~cr>-

~ ~SHINARUMP FORMATION

I ~ ~ IMOENKOPI FORMATION

IGNEOUS ROCKS

g ~ ~ m ) ~ASALT FLOWS- - - -

FAULT

...a.. .................

OVERTHRUST FAULT

~

PROSPECT

(NONE SHOWN IN MINING AREA)

0SIGNIFICANT RADIOACTIVE AREA

(AFTER D.L.EVERHART, A.E.G.)

SCALE OF FEET

° !5POO I0J:?OO! I

LEGEND FOR P l a t e I .

- 3



INTRODUCTION

The S i l v e r R e e f a r e a i n s o u t h w e s t e r n Utahm e r i t s g r e a t e r a t t e n t i o n t h a n i t has r e c e i v e d f o ri t c o n t a i n s t h e on ly known o c c u r r e n c e of commer-c i a l b o d i e s o f s i l v e r o r e i n s a n d s t o n e i n t h eU n i t e d S t a t e s . I t y i e l d e d a l m o s t $ 8 , 0 0 0 , 0 0 0 i ns i l v e r d u r i n g a d e c a d e t h a t i n c l u d e d t h e l a t e1 8 7 0 ' s and e a r l y 1 8 8 0 ' s f rom some 29 mines d i s -t r i b u t e d t h r o u g h an a r e a o f tw o s q u a r e m i l e s .

Fur the rmore , m i n e r a l s c o n t a i n i n g c o p p e r, vanadium,and uranium a r e a s s o c i a t e d with th e s i l v e r m i n e r -a ~ s so t h a t a p r o p e r s t u d y o f t h e S i l v e r R e e fd e p o s i t s may f u r n i s h compara t i ve d a t a t h a t shou ldbe o f v a l u e i n u n d e r s t a n d i n g d e p o s i t s of t h e s em e t a l s e l s e w h e r e i n t h e s e d i m e n t a r y r o c k s of th eColorado P l a t e a u . I t i s b e l i e v e d t h a t t h e m e t a l si n t h e S i l v e r Reef s a n d s t o n e were pr imary c o n s t i -t u e n t s o f o r i g i n a l v o l c a n i c t u f f s i n t h e C h i n l ef o r m a t i o n . These m e t a l s were d i s s o l v e d a n d / o rm e c h a n i c a l l y t r a n s p o r t e d by s t r e a m s which weree r o d i n g t h e t u f f a c e o u s s e d i m e n t s . They were d e -p o s i t e d w i t h t h e s a n d s t o n e s and s h a l e s o f t h eS i l v e r R e e f a r e a . F u r t h e r c o n c e n t r a t i o n o f t h em e t a l s i n t h e S i l v e r R e e f s a n d s t o n e was (1 ) bys o l u t i o n i n c i r c u l a t i n g g r o u n d w a t e r s a n d , (2 )by p r e c i p i t a t i o n because o f c o n t a c t wi th entombedp l a n t d e b r i s and a s s o c i a t e d b a c t e r i a . A newi n t e r p r e t a t i o n o f s t r u c t u r a l f e a t u r e s shou ld en -cou rage a d d i t i o n a l p r o s p e c t i n g i n th e S i l v e r Reefa r e a , n o t o n l y f o r m e t a l s b u t , i n t e r e s t i n g l ye n o u g h , f o r p e t r o l e u m .

PREVIOUS WORK

As much of t h e known ore ha s been e x t r a c t e d

and many o f t h e u n d e r g r o u n d w o r k i n g s a r e nol o n g e r a c c e s s i b l e , t h e r e c o r d e d o b s e r v a t i o n s o fe a r l i e r w o r k e r s a r e p a r t i c u l a r l y v a l u a b l e i ni n t e r p r e t i n g f e a t u r e s of t h e d i s t r i c t . R o l k e ri n 1881 d e s c r i b e d s e v e r a l o f t h e mines and h i sc a r e f u l o b s e r v a t i o n s on t h e Buckeye R e e f a r ev e r y h e l p f u l f o r t h e l a t e r s t u d y s i n c e most o f



t h e m i n e s on t h i s r e e f a r e now i n a c c e s s i b l e .R o t h w e l l , as e d i t o r o f t h e E n g i n e e r i n g and Min-in g J o u r n a l i n 1880 , summed up h i s o b s e r v a t i o n son th e d i s t r i c t . Pro fes so r J . S. Newberry r eco rdedd a t a on th e d i s t r i c t and o f f e r e d a t h e o r y on th eo r i g i n o f t h e s i l v e r d e p o s i t s i n 1 8 8 0 . L a t e r ,B u t l e r ( p p . 5 8 2 - 5 9 4 , 1 9 2 0 ) 1 i n h i s r e v i e w o ft h e o re d e p o s i t s of Utah summar ized t h e work o ff o r m e r w r i t e r s and added h i s own o b s e r v a t i o n &S e v e r a l b r i e f p r i v a t e r e p o r t s t o t h e d i f f e r e n tc o m p a n i e s which have o n e r a t e d i n t h e d i s t r i c twere w r i t t e n by B a l l ( 1 9 2 0 ) , Crane ( 1 9 2 0 ) ~Wroth( 1 9 2 0 ) , E l g i n and Wilson ( 1 9 4 6 ) , S t u g a r d (1951)and o t h e r s . B o t h D o b b i n ( p p . 1 2 1 - 1 4 4 , 1 9 3 9 )and G a r d n e r ( p p . 2 4 1 - 2 6 0 , 1 9 4 1 ) g e o l o g i c a l l ymapped t h e s u r r o u n d i n g a r e a i n some d e t a i l .

FIELD WORK

The w r i t e r b e g a n work i n t h e d i s t r i c t i nt h e f a l l o f 1 9 4 7 and c o m p l e t e d t h e f i e l d workd u r i n g weekends , h a l f o f December and two months

o f 1948. The known produc t ive a rea of th e d i s t r i c twas s u r v e y e d on a s c a l e o f 200 f e e t t o t h e i n c hand a l l o f th e a c c e s s i b l e work ings were i n s p e c t e dand some w e r e g e o l o g i c a l l y m a p p e d . The minea r e a s on t h e E a s t R e e f were a l s o s u r v e y e d ont h e same s c a l e . A b a c k g r o u n d g e o l o g i c map o fth e mining d i s t r i c t on a s c a l e o f one i n c h e q u a l so n e - h a l f m i l e was c o m p l e t e d on c o p i e s o f U. S.S o i l C o n s e r v a t i o n p h o t o s of t h e a r e a . The f i n a l

map was c o m p i l e d on a c o n t r o l l e d m o s a i c o f twoi n c h e s e q u a l s one m i l e .

An u n d e r g r o u n d map o f m o s t o f t h e knownwork ings was compi led from o ld maps o f t h e a r e a .I t i s r e g r e t t e d t h a t o the r maps of now i n a c c e s s i b l eworkings were n o t made a v a i l a b l e t o make th e com-p i l a t i o n more comple te . However, th e map does givea f a i r r e p r e s e n t a t i o n of the mines and t h e i r e x t e n t .

1 . ) r e f e r s t o r e f e r e n c e i n b i b l i o g r a p h ya t end o f r e p o r t .

- 5 -



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ACKNOWLEDGMENTS

No s t u d y o f any mining d i s t r i c t can be r e ps e n t a t i v e o f t h e d i s t r i c t w i t h o u t t h e wholeh ea rc o o p e r a t i o n o f t h e mine owner s and men who h

worked t h e r e . To t h o s e men who g a v e f r e e l yt h e i r t i m e and i n f o r m a t i o n I e x t e n d my t h a nS p a c e p e r m i t s o n l y t h e m e n t i o n o f a few. Mr.W. C o l b a t h , fo rmer owner o f t h e p r o p e r t y , was rn

k i n d i n g r a n t i n g p e r m i s s i o n t o s t u d y th e d i s t rand i n s u p p l y i n g unde rg round maps o f th e ThompsCobb a r e a and t h e Doyle s h a f t w o r k i n g s . H is dc u s s i o n o f t h e o t h e r m i n e s i n t h e a r e a was me n l i g h t e n i n g . Mr. E. W. Newman, g e o l o g i s t f o rA. S . & R. Company an d h i s a s s o c i a t e s d e s es p e c i a l t hanks f o r th e v a l u a b l e in fo rma t ion supp]on t h e work c o m p l e t e d by t h e i r company i n 19and f o r t h e c o p i e s of a l l th e unde rg round work1t h e y s a m p l e d and s u r v e y e d on t h e Buc k e ye ReMr. J a m e s E h r h o r n , S u p e r i n t e n d e n t o f t h e U.Mine a t Bingham, Utah was v e r y k i n d i n f u r n i s rt h e diamond d r i l l c o r e s o f f i v e h o l e s d r i l l e dt h e d i s t r i c t i n 1946 and i n s u p p l y i n g c o p i e sr e c o n n a i s s a n c e r e p o r t s made by h i s e n g i n e eO t h e r s who h a v e b e e n v e r y h e l p f u l a r e Mr. F rH a r t l e y and Mess r s . O s c a ~Wi l l a r d , and Bob McMu:of Leeds , Utah .

To my p a r t - t i m e a s s i s t a n t s Tom Gwynn,Johns , Herman Heath , Bob White , and my wife Marl e x t e n d my s i n c e r e t h a n k s . F i n a l l y , w i t h o u t

a i d o f a s m a l l f i e l d expense g r a n t f rom th e 1Depar tment o f P u b l i c i t y and I n d u s t r i a l Developm t

Raw M a t e r i a l s D i v i s i o n t h r o u g h A r t h u r L. CrawfcC o m m i s s i o n e r, and t h e g e n e r o u s f e l l o w s h i p andp e n s e a c c o u n t of t h e S h e l l O i l Company a t Ind:U n i v e r s i t y f o r t h e 1948-49 academic y e a r , muclt h e d a t a now p r e s e n t e d cou ld no t have been o b t a i

The s t u d y was done u n d e r t h e v e r y h e l l

guidance o f Dr. Eugene Cal laghan , former ProfessoEconomic G e o l o g y, I n d i a n a U n i v e r s i t y , and t ot h e w r i t e r e x t e n d s h i s d e e p e s t a p p r e c i a t i o nt h a n k s f o r h i s i n v a l u a b l e h e l p . C r e d i t i s :acknowle d g e d t o W. H. Moran f o r h i s d r a f t i n gand t o George R i n g e r and D r. C. F. Dei s s f o r tc o n s t a n t s u p p o r t .



LOCATION

The H a r r i s b u r g ( S i l v e r Ree f ) d i s t r i c t i s i nWash ing ton County i n s o u t h w e s t e r n U t a h . L e e d s ,a fa rming communi ty, p o p u l a t i o n 200 , i s j u s t n o r t ho f t h e c e n t e r o f t h e d i s t r i c t . The n e a r e s t r a i lroad i s a branch l i n e a t Cedar C i t y, Utah , 34 m i l e st o t h e n o r t h and 2300 f e e t h i g h e r . U. S . Highway91 l i e s one m i l e e a s t o f t h e f o r m e r p r o d u c t i v em i n e s o f t h e d i s t r i c t .

The r e g i o n i s s e m i - a r i d , and t h e w i n t e r s a re

m i l d , b u t th e summers a re h o t . R a i n f a l l a t Ander-s o n ' s Ran c h , tw o m i l e s n o r t h o f L e e d s , a v e r a g e d12 .69 i nches pe r y e a r over a 27 y e a r p e r i o d . Table1 l i s t s t h e month ly a v e r a g e f o r t h e same p e r i o d .

*ab le 1 . Monthly R a i n f a l l Average - 27 Year Per iodAnderson ' s Ranch, 2 mi le s North of Leeds , Utah

Month Average Month Average

January . . . . . . . . . 1 . 74 Ju ly . . . . . . . . . . . . 0 .73

February . . . . . • . . 1 . 9 4 Augus t . . . . . . . . • . 0 .92Marc h • • . • • . • . • . . 1 .31 September . • . . . . . 0 .59Apri l • . . . . . . . . . . 1 .04 October . . . . . . • . • 1 . 0 2May • • • . • • . • . . . . • 0.65 November . . . . . . . . 0 .77June . . . . . . . . . . . . 0 .31 December • . . . . • . . 1 . 6 7

Annual Average - same per iod 12 .69 i nches .

*

U . S . D e p a r t m e n t o f Commerce , We a t h e r B u r e a u ,G. K. G r e e n i n g , M e t e o r o l o g i s t .

- 7 -



Water i s s c a r c e , and th e main source i s Qua i lC r e e k , which d r a i n s a p o r t i o n o f t h e P i n e Va l l e yM o u n t a i n s t o t h e w e s t . The s t r e a m s u p p l i e s th emines and t h e town of Leeds w i t h w a t e r f o r b o t h

c u l i n a r y and i r r i g a t i o np u r p o s e s . A

few s m a l lp e r e n n i a l s p r i n g s a few hundred f e e t wes t of Leedsa r e u t i l i z e d f o r i r r i g a t i o n and c a t t l e . The onlyo t h e r s t r e a m i n th e d i s t r i c t i s t h e Vi rg i n R i v e ri n t h e s o u t h e a s t p a r t of t h e a r e a which l i e s 300-400 f e e t l o w e r t h a n S i l v e r R e e f . The w a t e r i sused f o r i r r i g a t i o n a t Washing ton and S t . Georget o t h e s o u t h . The Stormont M i l l , now d i s m a n t l e d ,once m i l l e d o re on th e r i v e r n e a r i t s i n t e r s e c t i o n

wi th th e E a s t Reef . Of th e e s t i m a t e d 15 m i l e s ofu n d e rg r o u n d w o r k i n g s i n t h e a r e a , p r o b a b l y 50%

a re f l o o d e d w i t h w a t e r . In c a s e o f d r o u g h t mosto f t h i s w a t e r could be r e c o v e r e d by r e h a b i l i t a t i n gt h e A.S.&R. Co. s h a f t and pumping from th e 460 level.

Timber i s s c a n t y o r a b s e n t n e a r t h e m i n e s ,b u t f a i r g r o w t h s o f c e d a r , j u n i p e r , and p i n es u i t a b l e f o r mine u s e c o v e r th e l e s s p r e c i p i t o u ss l o p e s o f t h e Pine Va l l e y Mounta ins s i x m i l e s t ot h e w e s t . T h e r e i s a s p a r s e g r o w t h o f d e s e r tt y p e p l a n t s , m a i n l y s a g e b r u s h and v a r i e t i e s ofc a c t u s n e a r th e m i n e s . Where w a t e r i s a v a i l a b l ef o r i r r i g a t i o n p u r p o s e s f a r m i n g i s e x t e n s i v e l yp r a c t i c e d i n th e s m a l l f l a t v a l l e y s . Some c a t t l ea r e r a i s e d i n t h e a r e a , b u t t h e s e a re s e c o n d a r yi n i m p o r t a n c e t o f r u i t g r o w i n g .

SURFACE FEATURES

R e l i e f i n th e a r e a o f t h e mines i s n o t moret h a n 1000 f e e t . The o ld town of S i l v e r Reef , now

r e p r e s e n t e d by on ly two h a b i t a b l e b u i l d i n g s andnumerous o l d r o c k f o u n d a t i o n s and s t o n e w a l l s ,l i e s on a b o u l d e r - s t r e w n t e r r a c e a t a p p r o x i m a t e l y4000 f e e t e l e v a t i o n . The mines t h e m s e l v e s a reon th e f ace and d ip s lope of r i d g e s of ledge-makings a n d s t o n e and r a n g e i n e l e v a t i o n from l e s s t h a n3600 f e e t t o 4000 f e e t l To t h e wes t r e s i s t a n t

,

2 . Mine e l e v a t i o n s were e s t a b l i s h e d on an assumeddatum of 4000 f e e t f o r U.S. Minera l Monument #1.S i n c e a l l f o r m e r unde rg round maps a r e on t h i sda tum, th e w r i t e r ' s su rvey a l s o u t i l i z e s t h e s ee l e v a t i o n s .



r e d s a n d s t o n e c l i f f s r i s e a l m o s t a t h o u s a n d f e e tabove t h e S i l v e r Reef A r e a . F a r t h e r ~ e s t i g n e o u sr o c k s o f t h e Pine Va l l e y M o u n t a i n s form p r e c i p i t -ous s l o p e s ~ h i c hr i s e t o a l t i t u d e s of ove r 1 0 , 0 0 0

f e e t . E a s t of th e d i s t r i c t t h e impos ing Hur r i caneC l i f f s e p a r a t e s t h e d o ~ n f a u l t e dS t . George B a s i nfrom th e main C o l o r a d o P l a t e a u P r o v i n c e . F a r t h e rt o t h e e a s t and n o r t h a s t a i r ~ a yo f l e d g e s r i s e st o t h e Z i o n Canyon N a t i o n a l P a r k Monument a r e aan d b e y o n d t o t h e C o l o b P l a t e a u t o more t h a n1 0 , 0 0 0 f e e t i n e l e v a t i o n .

Leeds l i e s i n a s y n c l i n a l v a l l e y c u t i n s o f t

s h a l e sb e t ~ e e n

r e s i s t a n t s a n d s t o n e l e d g e s . Nor th -e a s t ~ a r d - d i p p i n ghogbacks o f g r i t and cong lomer a t ef l a n k a breached a n t i c l i n e ~ h i c he x t e n d s 18 m i l e st o t h e s o u t h ~ e s t .The s o f t s h a l e s i n t h e c o r e oft h i s a n t i c l i n e have been i n t r i c a t e l y e r o d e d i n t oa b a d l a n d s t y p e o f t o p o g r a p h y . Ve g e t a t i o n i sp r a c t i c a l l y a b s e n t h e r e and t h e l o c a l name " P u rg a -t o r y " has been a p p r o p r i a t e l y a p p l i e d .

- 9 -



1

111

~~mmm

~..~E j~

- ! o

EXPLANATION

SEDIMENTARY ROCKS

ALLUVIUM

BOULDER ALLUVIUM

DUFFIN SANDSTONE AND SHALE

TECUMSEH SANDSTONE

LEEDS SANDSTONE

zo

~;:;;a:oLL

TRAIL HILL SANDSTONE AND SHALE ~

FIRE CLAY BENTONITIC SHALE

HARTLEY SHALE AND SANDSTONE

STRIKE AND DIP OF JOINTS

VERTiCAL JOINTS

NORMAL FAULT

OVERTHRUST FAULT

TRIASSIC STREAM DIRECTiON

SHAFT

TUNNEL

z

I

U

PI a t e I I GEOLOGIC MAP OF SILVER REEF MINING AREA,




N

W-++--4- E

o !500 1000 1500 2 0 0 0 FEETL' ~ ' ~ ~ ' ~ ' L -__ ~ ~ '_ _ _ _ _ L - _ _ ~ ,

CONTOUR INTERVAL 40 FEET

CHRISTY TAILINGDUMP

P l a t e I I . GEOLOGIC MAP OF SILVER REEF MINING AREA,


- 1 1 -



GEOLOGIC SETTING

SEDIMENTARY ROCKS

The s e d i m e n t a r y r o c k s o f t h e S i l v e r Reef a r e ar a n g e i n age f rom Lower T r i a s s i c t o J u r a s s i c anda re t y p i c a l of th e s t r a t i g r a p h i c sequence i n s o u t hw e s t e r n U t a h and C o l o r a d o P l a t e a u . The r o c k sc l o s e l y r e s e m b l e t h o s e so w e l l known t o v i s i t o r sof nea rby Zion N a t i o n a l P a r k . S a n d s t o n e s , s h a l e s ,s i l t s t o n e s , and muds tones a re t h e i m p o r t a n t l i t h

o l o g i c t y p e s . With t h e e x c e p t i o n of t h e Vi r g i nl i m e s t o n e member i n t h e l o w e r p a r t of t h e Moenk o p i f o r m a t i o n w h i c h c o n t a i n s m a r i n e f o s s i l s ,a l l t h e r o c k s a r e b e l i e v e d t o have been d e p o s i t e du n d e r n o n - m a r i n e c o n d i t i o n s . The o n l y f o s s i l st h u s f a r found n e a r S i l v e r Reef above t h e Vi r g i nl i m e s t o n e a r e f r a g m e n t s o f t r e e s , r u s h e s , andr e e d s . W i t h i n t h e p a r t of t h e S i l v e r R e e f a r e at h a t was mapped , t h e l o w e r T r i a s s i c Moenkopi and

t h e u p p e r T r i a s s i c S h i n a r u m p and C h i n l e a r e t h ef o r m a t i o n s w i t h w h i c h t h i s s t u d y i s c o n c e r n e d .More d e t a i l e d d e s c r i p t i o n i s devo ted t o t h e Chin l et h a n t h e o t h e r f o r m a t i o n s i n t h e f o l l o w i n g p a g e sb e c a u s e i t c o n t a i n s t h e s i l v e r - b e a r i n g h o r i z o n .

Moenkopi F o r m a t i o n

Wi t h t h e e x c e p t i o n o f t h e b a s a l p o r t i o n ,

mos t o f , t h e Moenkopi f o r m a t i o n i s v e r y w e l l e xposed i n th e S i l v e r Reef a r e a . Rees ide and B a s s l e r( p p . 5 9 - 6 2 , 1 9 2 2 ) d e s c r i b e d a s e c t i o n n e a r t h eH a r r i s b u r g dome i n c l u d i n g t h e unmapped Vi r g i nl i m e s t o n e member two mi les sou th of th e a r e a coveredby t h i s r e p o r t . In a d d i t i o n , Hunt ing ton and Goldt h w a i t ( p p . 1 0 1 - 5 9 , 1 9 0 4 ) , B u t l e r ( p p . 5 8 3 - 5 9 4 ,1 9 2 0 ) , G a r d n e r ( p p . 2 4 1 - 2 6 0 , 1 9 4 1 ) , and G r e g o r yand Wil l iams (pp . 224-228 , 1947) have a l l d e s c r i b e d

o r named t h e r o c k s i n t h e s u r r o u n d i n g c o u n t r y ,though t h e r o c k names of Hunt ing ton and Gold thwa i thave been s u p e r s e d e d by more r e c e n t c o r r e l a t i o n s .R e e s i d e and B a s s l e r ( p . 5 5 , 1922) s u b d i v i d e d t h eMoenkopi i n t o t h e Rock Canyon c o n g l o m e r a t e , Vi rg i nl i m e s t o n e , and Shnabkaib members i n ascend ing o r d e r.

12



Only t h e Shnabka ib member i s i n c l u d e d i n t h e mapped a r e a . F u r t h e r s u b d i v i s i o n seemed u n w a r r a n t e d .

The Moenkopi i s exposed on ly i n t h e b r e a c h e da n t i c l i n e i n th e a r e a c a l l e d P u rg a t o r y j u s t n o r t ho f t h e H a r r i s b u r g - H u r r i c a n e r o a d f o r o v e r a d i st a n c e o f f o u r and a h a l f m i l e s . The s a n d s t o n e s ,s o f t s h a l e s , m u d s t o n e s , an d m i n o r gypsum b e d shave been eroded and an i n t r i c a t e d r a i n a g e p a t t e r nh a s b e e n d e v e l o p e d t h a t p r o v i d e s good e x p o s u r e ~

From a v a n t a g e p o i n t o v e r l o o k i n g P u r g a t o r y b a s i nt h e b r i g h t l y c o l o r e d Moenkopi s e c t i o n appears as a

s e r i e s of c o l o r e d bands w r a p p i n g a round t h e n o s eo f t h e a n t i c l i n e . G r a y s , w h i t e s , and p i n k s p r e

d o m i n a t e n e a r t h e b a s e o f t h e s e c t i o n e x p o s e d ,w h e r e a s r e d and maroon c o l o r t h e u p p e r p a r t . A

s e c t i o n of 376 f e e t of Moenkopi (Shnabkaib member)was measured j u s t n o r t h of th e Har r i s b u rg -Hur r i c aner o a d .

L i t h o l o g i c a l l y th e member exposed may be d iv i d e d i n t o f o u r d i s t i n c t i v e u n i t s : (1) an u n d e rl y i n g s e r i e s o f w h i t e t o l i g h t r e d g y p s i f e r o u s

s h a l e s and m u d s t o n e s w i t h m i n o r s a n d s t o n e ( n o tm e a s u r e d ) ; (2 ) 54 f e e t o f v a r i e g a t e d b r i c k - r e ds h a l e s w i t h minor i n t e r b e d d e d y e l l o w i s h , micaceouss h a l e s ; (3 ) 60 f e e t o f c r e a m i s h y e l l o w, h i g h l yc r o s s - b e d d e d , somewhat i r o n s t a i n e d f r i a b l e s a n ds t o n e ; and (4) 262 f e e t o f b r i c k - r e d t o b r o w n i s hre d s h a l e s , sandy s h a l e s , s a n d s t o n e and muds tones .

The measured s e c t i o n i s as f o l l o w s :

S e c t i o n o f exposed Moenkopi f o r m a t i o n i n P u rg at o r y B a s i n , North of H a r r i s b u r g - H u r r i c a n e r o a d ,

Wash ing ton County, U t a h .

Shinarump24' P l a t y f i n e - b e d d e d r e d s h a l e s , mUdstones . Reed

i m p r e s s i o n s .3 ' C r o s B ~ b e d d e d 7micaceous sandy mudstone .41 P l a t y , f i n e - g r a i n e d a r g i l l a c e o u s s a n d s t o n e ,

hardy r i p p l e - m a r k e d .7 ' Fine - g ra ine d a r g i l l a c e o u s b r i c k - r e d s a n d s t o n e .2 0 ' Red f i n e - g r a i n e d red mass ive s ands tone .1 0 ' Micaceous , t h i n - b e d d e d , sandy mUdstone.

5' Fine - g ra ine d muddy b r i c k - r e d s and s t o n e .

- 13 -



1 0 5 ' S o i l w e a t h e r i n g , b r i c k - r e d s h a l e s and muds t o n e s . Gypsum l a y e r s p r e s e n t . Base g r e e ngray micaceous s a n d s t o n e , uppe r p a r t main ly

b r i c k red mudstone, t h i n gypsum l a y e r s p a ra l l e l t o bedd ing . Upper o n e - f o u r t h re d andminor g r a l micaceous s h a l e s and some s a n d -s t o n e s .

5 0 ' B r i c k - r e d s h a l e s and muds tone , u p p e r p o r t i o nq u i t e m i c a c e o u s sandy s h a l e . Lower o n et h i r d r i p p l e marked. E a s i l y eroded member.

6 0 ' Ye l l o w, h i g h l y c r o s s - b e d d e d , i r o n s t a i n e dg r i a b l e s a n d s t o n e . May be q u i t e a r g i l l a

c e o u s . Contac t f l u t i n g and p i t t i n g c h a r a ct e r i s t i c . G o o ~ l e d g emaker.5 4 ' Va r i e g a t e d b r i c k - r e d , micaceous sands tone and

s h a l e s . Minor i n t e rbedded yel low micaceouss h a l e s . Red predominant c o l o r. Weak member.

G y p s i f e r o u s gray t o p i n k i s h and r e d s h a l e andm u d s t o n e s . E a s i l y e r o d e d member. (Notme a s u r e d . )

Shinarump Conglomerate

The Sh ina rump c o n g l o m e r a t e i s d o u b t l e s s oneo f t h e mos t i n t e r e s t i n g f o r m a t i o n s i n th e s o u t hw e s t e r n U n i t e d S t a t e s . T h i s f o r m a t i o n r a n g e s i na r e a l e x t e n t from n o r t h w e s t e r n New Mexico ( S e a r s ,J . , p . 1 0 , 1925) and a c r o s s s o u t h e r n Utah ( B a k e r,p • 3 7 , 1933; G eg 0 r y , H. B . & Moo r e , R . C . , P • 52,1 9 3 1 ) and n o r t h e r n A r i z o n a ( L o n g w e l l , e t . a l . ,

p p . 9 - 11 , 1925) i n t o s o u t h e a s t e r n (Longwel l , C. R .,p . 5 2 , 1928) and s o u t h e r n Nevada ( H e w e t t , D. F . ,p . 3 4 , 1 9 3 1 ) . In a l m o s t e v e r y p u b l i s h e d d e s c r i pt i o n t h e l i t h o l o g y i s t h e s a m e , t h e t h i c k n e s sseldom exceeds 100 f e e t , and i t s p r imary s t r u c t u r e sa r e s i m i l a r . The s o u r c e of t h e Shinarump and i t smode of d e p o s i t i o n c o n s t i t u t e one of th e i n t r i g u i n gp r o b l e m s o f t h e C o l o r a d o P l a t e a u and t h e r e g i o nt o t h e w e s t ( S t o k e s , p . 1 3 8 3 , 1 9 4 8 ) .

The r e s i s t a n t Shinarump f o r m a t i o n l i e s betweena s e r i e s of deep r e d s a n d s t o n e s and s h a l e s wherei t s brown t o g r a y i s h - b r o w n and b u f f c o l o r s a r e i nm a r k e d c o n t r a s t t o t h e e n c l o s i n g r o c k s . I t i se s s e n t i a l l y 115 f e e t of c o a r s e - g r a i n e d s a n d s t o n e



v i t h a b u n d a n t i n t e r b e d d e d p e b b l e c o n g l o m e r a t e s .P e b b l e s i n t h e c o n g l o m e r a t e s r a r e l y e x c e e d ani n c h i n d i a m e t e r and c o n s i s t c h i e f l y o f q u a r t zand q u a r t z i t e , t hough c h e r t and l e s s e r l i m e s t o n epebbles do occur. Reeside and B a s s l e r (p . 73, 1922)r e p o r t e d i gneous rock p e b b l e s i n t h e s e c t i o n t h e ymeasured n e a r Vi rg i n C i t y , though no such p e b b l e sve re observed i n th e S i l v e r Reef a r e a . Rapid l e n si n g o f t h e i n t e r b e d d e d p e b b l e c o n g l o m e r a t e s andsome o f t h e s a n d s t o n e s i s c h a r a c t e r i s t i c o f t h ef o r m a t i o n . An abundance o f f r a g m e n t s o f f o s s i lyood and i m p r e s s i o n s o f r u s h e s and r e e d s may bel o c a l l y p r e s e n t n e a r t h e t o p of t h e f o r m a t i o n .Stream c r o s s - b e d d i n g and c h a n n e l s a r e a b u n d a n t .L o c a l u n c o n f o r m i t i e s or f i l l i n g o f f o r m e r s t r e a mc h a n n e l s y e r e obse rved i n t h e u n d e r l y i n g Moenkopifo rmat ion . A f l u v i a t i l e o r i g i n i s sugges t ed .

The Shinarump forms b o l d l e d g e s t h a t i n c l u d et h e s o u t h Ye s t Ya r d - t r e n d i n g r i d g e s o u t h and y e s to f th e Leeds c e m e t e r y and t h e nose and p r o m i n e n te n c i r c l i n g h o g b a c k e n c l o s i n g P u r g a t o r y B a s i n .J o i n t s a re p r o m i n e n t l y exposed i n t h e b e d s . Fromt h e S i l v e r Reef a r e a t h e Shinarump c r o p s o u t f o rmany m i l e s s o u t h a l o n g U. S. Highyay 9 1 , t o w a r d sS t . George , Utah .

Shinarump Conglomera te S e c t i o n Nor th of t h eH a r r i s b u rg - H u r r i c a n e Road

Chin l e Fo rma t ion .

1 5 ' M a s s i v e , r e d d i s h , c o a r s e - g r a i n e d s a n d s t o n e .1 6 ' Yel loy t o l i g h t r e d , p l a t y , c ros s -bedded sand

s t o n e .1 5 ' M o d e r a t e b r o w n , c o a r s e - g r a i n e d s a n d s t o n e .

Yellow s t r e a k s p a r a l l e l t o bedd ing . F o s s i lyood.

35' 2 0 ' g r a y i s h y e l l o w t o d a r k y e l l o w i s h - o r a n g e

g r i t , p i t t e d and f l u t e d w e a t h e r e d s u r f a c e .1 5 ' g r i t and s a n d , s m a l l l e n s e s of c o ng l o m e r a t e . B u f f , smooth w e a t h e r i n g .

- 15 -



3 4 ' G r i t and p e b b l e c o n g l o m e r a t e , s t r e a m c r o s sbedd ing p rominen t . Pebb le s t o 1" d i a m e t e r ,main ly q u a r t z and q u a r t z i t e .

11 5 ' To t a lMoenkopi Forma t ion .

Ch in le Forma t ion

A ney s t r u c t u r a l i n t e r p r e t a t i o n i n th e S i l v e rReef a r e a has f o r c e d a change i n th e s t r a t i g r a p h i cs e c t i o n o r i g i n a l l y d e s c r i b e d by B a l l ( 1 9 2 0 ) , Crane( 1 9 2 0 ) , R o l k e r ( p p . 2 2 - 2 4 , 1881) and t h a t no ted

by B u t l e r ( p p . 5 8 6 - 7 , 1920) f o r t h e S i l v e r Reefa r e a . A d e t a i l e d d e s c r i p t i o n of th e Chin le fo rmat i o n seems y a r r a n t e d as i t c o n t a i n s t h e economic a l l y i m p o r t a n t S i l v e r R e e f s a n d s t o n e . However,t h e s c a l e p e r m i t s s h o w i n g o n l y t h r e e members oft h e Chin le f o r m a t i o n on th e g e o l o g i c map ( P l a t e n,b u t s u b d i v i s i o n i n t o s e v e n members i s n e c e s s a r yf o r c a r e f u l s t r a t i g r a p h i c and s t r u c t u r a l work i nt h e mine a r e a .

With in th e S i l v e r Reef a r e a th e Chin le fo rmat i o n c o n s i s t s of a b o u t 1100 f e e t o f a l t e r n a t i n gs a n d s t o n e s and s h a l e s w i t h t h e e x c e p t i o n o f twos m a l l beds of c h e r t y l i m e s t o n e n e a r th e o ld S i l v e rReef ceme te ry. On th e b a s i s of c o l o r and l i t h o l o g yt h e f o r m a t i o n i s s u b d i v i d e d i n t o a l o w e r memberc o n s i s t i n g p r e d o m i n a n t l y o f d a r k r e d s h a l e s andm i n o r i n t e r b e d d e d r e d s a n d s t o n e s 265 f e e t t h i c ko v e r l y i n g t h e S h i n a r u m p f o r m a t i o n , a p r o m i n e n t5-15 f o o t b ed o f w h i t e a r k o s i c s a n d s t o n e , 1 0 - 1 5f e e t o f p u r p l i s h t o b l u i s h - g r a y b e n t o n i t i c s h a l e sw i t h i n c l u d e d banded c h e r t , 310 f e e t of deep r e dt o b r i c k r e d s a n d s t o n e and s h a l e s w i t h an i n c l u d e done f o o t b e d o f w h i t e s i l i c i f i e d l i m e s t o n e , 65f e e t o f b u f f w e a t h e r i n g t o w h i t e s a n d s t o n e o y e rl a i n by 35 f e e t o f l a v e n d e r t o p u r p l e s a n d s t o n e

t o g e t h e r known a s t h e S i l v e r Ree f s a n d s t o n e (Rees i d e and B a s s l e r ~p e 62y 1 9 2 2 ) and f i n a l l y t h eu p p e r C h i n l e which c o n s i s t s of more t h a n 400 f e e to f r e d s h a l e s and s a n d s t o n e s w i t h some w h i t e ,f r i a b l e s a n d s t o n e b e d s which l o c a l l y a re 10 f e e to r more i n t h i c k n e s s .

16



I-;t)

1"'-(,,f"(:

~>1(1)

~

::s:(1)

Q.lm~

' i(1)

P-

m(1)( )

~ c+-' l

~ J .

0~[J]

0H)

0:;r'~ .

:;1I- '(0

H)

0' iSQ.lc+~ .

0t;j

Section in Smi.thls ),Iesa(3 lW.es narth o! V i r g ~City, Utah)

Reeside an d Bassler, P. P. ]29, p . 55

Brick..;red to deep-c'6dshale and sandstone

Mas a i v a, madil.llll-gl"a.inedmauve sandstone, crossbedded an d ripple mark2d

Section a t Silver HeefthiB report

Deep..;red to bright red shaleswith minor interbeddedwhite to re d sandstones.427 1

- - - - - , -

\'/hite, butf , lavender, f inegrained, somewhat crossbedded sandstone. Local.lycontains foss i l rushes,reeds, and wood.

Brick-red sandstone an d sba.le

Variable coarse arkosic crossbedded sandstone, banded withgray, white, and mauve, an dcontaining foss i l wood.Locally knovm as th eIIJilver j ( ee f sandstone".

Vaxiegated llgumboll clay sba.le,bluish gray, greenish grtq,mauve, red, and rarelybrovm, contains foss i lwood.

Shinarump Conglo merate. 5<> 100I . .. I

Vertical ScalA

Silver Reef sandstone.

Brick-red sandstones and sba.less o ~ cross-bedded. Gray,green, and maroon sba.le a t

top. Near base a bluishgray bentoni t ic be d withprominent calcareous concretions an d geodas.

Coarse-g.rained, arkosic , crossbedded, white sandstone.Contains foss i l wood.

Dark..;red to brick-red shaleswith thin interbedded sandstones.

Sh:inarulIlp Conglomerate.

------------



The C h i n l e f o r m a t i o n i s e x p o s e d t h r o u g h o u tt h e S i l v e r Reef a r e a and p a r t i c u l a r l y on t h e E a s tl i m b o f t h e Vi r g i n a n t i c l i n e where much o f t h eQua te rna ry a l l uv ium has been s t r i p p e d away. Ty p i -c a l l y , t h e C h i n l e f o r m s g e n t l e s l o p e s w i t h t h ee x c e p t i o n of t h e more r e s i s t a n t s a n d s t o n e membersw i t h i n t h e f o r m a t i o n which c rop ou t as bo ld c l i f f s .From Leeds w e s t t o t h e h i g h r e d s a n d s t o n e c l i f f sa l l th e r o c k s exposed a re Ch in l e e x c e p t f o r a l i n eo f Sh ina rump o u t c r o p s j u s t w e s t and s o u t h o f t h et o w n . The g e n t l y r o l l i n g s u r f a c e w e s t o f H i g h -way 91 n e a r H a r r i s b u rg and s o u t h toward S t . Georgeshows t h e c h a r a c t e r i s t i c w e a t h e r i n g of t h e f o r m a -t i o n . W i t h i n t h i s s e c t i o n t h e p r o m i n e n t S i l v e rR e e f s a n d s t o n e s t a n d s o u t as a r i d g e a b o v e t h es o f t s h a l e s . Nor th and e a s t of Leeds much of t h eC h i n l e i s c o v e r e d by Q u a t e r n a r y a l l u v i u m and windblown s a n d .

Lower C h i n l e Member

The l o w e r C h i n l e member i s m a i n l y a s e r i e so f b rown t o r e d s a n d s t o n e s and s h a l e s w i t h somegypsum and p o s s i b l y minor s a l t which occu r s be tweent h e Shinarump f o r m a t i o n and t h e S i l v e r Reef s a n d -

s t o n e member o f t h e Chin le f o r m a t i o n . The memberi s 620 f e e t t h i c k , e a s i l y w e a t h e r e d , and forms th es t r i k e v a l l e y s b o t h e a s t and w e s t o f L e e d s . F orc l a r i t y of d e s c r i p t i o n and mapping p u r p o s e s t h emember i s f u r t h e r s u b d i v i d e d and d e s c r i b e d u n d e rt h e f o l l o w i n g : Har t l ey s h a l e s and s a n d s t o n e s , F i r eClay H i l l b e n t o n i t i c s h a l e s , and T r a i l H i l l s a n d -s t o n e . T h e s e names a r e a p p l i e d t o l o c a l a r e a so n l y and s h o u l d n o t be c o n s i d e r e d a p p l i c a b l e t ob e d s o f any g r e a t a r e a l e x t e n t w i t h i n t h e l o w e rC h i n l e member.

18



H a r t l e y s h a l e s and s a n d s t o n e s .

These a re named f o r t h e e x p o s u r e s m e a s u r e d

n o r t h w e s t of th e Leeds Cemetery where 280 f e e t ofp r e d o m i n a n t l y d e e p r e d s h a l e s and l e s s e r f i n eg r a i n e d s a n d s t o n e beds main ly only a few i n c h e s i nt h i c k n e s s o v e r l i e t h e Sh ina rump f o r m a t i o n . Thebeds r e a d i l y w e a t h e r and s u b s e q u e n t v a l l e y s havebeen e roded i n them whereve r t hey a re e x p o s e d , asshown p a r t i c u l a r l y w e s t o f Leeds and s o u t h a l o n gt h e s t r i k e . Good e x p o s u r e s of t h i s s e c t i o n a r ed i f f i c u l t t o f i n d . Toward t h e to p of t h e s e c t i o n

s m a l l s lumped a r e a s i n th e re ds h a l e s

a re i n d i c at i v e of s a l t which has been d i s s o l v e d away. Minorgypsum a l s o occu r s i n t h i s s e c t i o n .

A p r o m i n e n t c l i f f - f o r m i n g b e d o f a r k o s i cs a n d s t o n e a t t h e t o p of t h e H a r t l e y beds i s 5-15f e e t t h i c k and w e a t h e r s l i g h t brown t o w h i t e .I t i s w e l l e x p o s e d a t t h e f o o t o f t h e BuckeyeR e e f n e a r Tecumseh H i l l and s o u t h w a r d . On t h e

Eas t Reef t he a rkos i c sands tone c rops out a long th eb a c k s l o p e o f t h e S h i n a r u m p h o g b a c k where manyp e t r i f i e d t r e e s and some c o a l - l i k e m a t e r i a l occu ri n i t . Two s i l i c i f i e d t r e e s o v e r 20 f e e t i nl e n g t h and two and o n e - h a l f f e e t i n d i a m e t e r werefound i n t h e s a n d s t o n e s o u t h of L e e d s . Remainso f o l d t r e e t r u n k s , now c o m p l e t e l y s i l i c i f i e do c c u r i n t h i s bed on t h e E a s t Reef n o r t h o f t h eDuff in Mine. L o c a l l y t h e s a n d s t o n e f i l l s channe l s

i n th e u n d e r l y i n g s h a l e s b u t i n g e n e r a l th e s t r i k eand d i p a r e t h e same as t h o s e o f t h e u n d e r l y i n gb e d s . The a r k o s i c s a n d s t o n e has been i n c o r r e c t l yc o r r e l a t e d w i t h t h e s a n d s t o n e j u s t w e s t of Leedsby B a l l ( 1 9 2 0 ) , who r e f e r s t o i t as t h e " B u t t eR e e f s a n d s t o n e . "

F i r e Clay H i l l b e n t o n i t i c s h a l e s

The b e s t exposu re s of th e F i r e Clay H i l l b e nt o n i t i c s h a l e s o f t h e l o w e r C h i n l e a r e on t h eE a s t Reef 1000 f e e t n o r t h of th e D u ff i n Mine whereth e s h a l e s conformably ove r ly th e a r k o s i c sands toneand a r e g r a y t o p u r p l i s h . A d i s t i n c t i v e f l u f f y

- 19 -



s o i l i n d i c a t i v e of b e n t o n i t e , wi th g e n t l e t o s t e e ps c a r p s , c h a r a c t e r i z e s t h e w e a t h e r e d o u t c r o p o ft h e s e gray t o p u r p l i s h beds . Th e t h i c k n e s s changes

a l i t t l e f rom t h e E a s t R e e f t o t h e West R e e f s ,b u t t h e ave rage i s 10-13 f e e t . Towards t h e b a s e ,c a l c a r e o u s c o n c r e t i o n s and geodes as much as s i xi n c h e s i n d i a m e t e r o c c u r s p o r a d i c a l l y , and i np l a c e s a r e a s s o c i a t e d w i t h c o n c r e t i o n s o f i r o no x i d e and d i s t i n c t i v e c o p p e r - b e a r i n g c o n c r e t i o n sup t o f i v e i n c h e s i n d i a m e t e r . A s s a y s o f t h ec o p p e r c o n c r e t i o n s show c o n s i d e r a b l e c o p p e r , somes i l v e r , and a f a i r showing of go ld as g iven below:

Tab le 2 . Assay R e p o r t on C o n c r e t i o n s FromF i r e Clay H i l l B e n t o n i t i c Sha le s

CopperS i l v e rGoldI r o n

I n s o l u b l e

30.90%1 . 8 5 o z s . / t o n0 . 1 4 o z s . / t o n8.30%

41.60%

CopperS i l v e rGoldI r o n

I n s o l u b l e

c

0.15%0 .20 o z s . / t o nNone

0.50%

6.40%

An a g a t e bed banded w i t h r e d , o r a n g e , g r e e n ,y e l l o w, and whi te occurs a t th e base of t h e s h a l e s .I t r a n g e s i n t h i c k n e s s from a f r a c t i o n of an i n c ht o a l m o s t a f o o t and i s r e m a r k a b l y p e r s i s t e n t ont h e Buckeye Reef t o a p o i n t n e a r i t s j u n c t i o n witht h e White R e e f . The a g a t e bed a l s o c r o p s o u t b elow th e White Reef f o r a d i s t a n c e o f s e v e r a l mi lest o t h e s o u t h . The b e s t e x p o s u r e s a re a t t h e baseof F i r e Clay H i l l s o u t h of t h e o ld town of S i l v e rR e e f . On t h e E a s t R e e f t h e same b e d s o f s h a l ea r e p r e s e n t , b u t t h e a g a t e bed m a y o r may n o t bea t t h e b a s e . At one p l a c e t h e a g a t e bed was o bs e r v e d t o c u t a c r o s s t h e b e d d i n g a t a s l i g h ta n g l e . In p l a c e s n e a r t h e t o p , round c h e r t p e bb l e s w e a t h e r o u t o f t h e s h a l e s . The s t r i k i n gc o l o r , c o n c r e t i o n s , g e o d e s , n o d u l e s , and o t h e ra s s o c i a t e d f e a t u r e s make t h e F i r e Clay H i l l b e nt o n i t i c s h a l e s an e x c e l l e n t key hor i zon f o r mappingp u r p o s e s . The s h a l e s a re p r e s e n t below th e Bucke y e , W h i t e and E a s t R e e f s , and t h e i r a p p a r e n tabsence unde r th e B u t t e Reef i s e x p l a i n e d by a l l uvium which cove r s t h e p r o b a b l e o u t c r o p .



OYing t o th e u n u s u a l c h a r a c t e r o f t h e s e bedsand t h e spo rad i c d i s t r i b u t i o n of g o l d , s i l v e r , andcoppe r i n c o n c r e t i o n s a d e t a i l e d s t u d y o f s e v e r a lsamples y as made. I t yas noted p a r t i c u l a r l y t h a ti n y a t e r t h e s h a l y m a t e r i a l s q u i c k l y a b s o r b e dy a t e r and expande d t o f o u r o r more t i m e s t h e i ro r i g i n a l vo lume . Th i s p r o p e r t y i s i n d i c a t i v e o fb e n t o n i t e and d o u b t l e s s e x p l a i n s t h e f l u f f y s o i lon t h e o u t c r o p s . As says f o r g o l d , s i l v e r , andc o p p e r y e r e run on s e v e r a l samples c u t a c r o s s t h eb e d s . Tyo t y p e s o f m a t e r i a l y e r e c o l l e c t e d :(1 ) y e l l o x i d i z e d , e x p a n d e d , f l u f f y v a r i e t y and(2 ) f r e s h , s h a l e - l i k e m a t e r i a l . R e s u l t s o f t h ea s s a y s a r e l i s t e d b e l o y :

Ta b l e 3 . A s s a y R e p o r t on F i r e C la y H i l l B e n -t o n i t i c S h a l e s , S i l v e r R e e f , U t a h .

Gold S i l v e r Copper D e s c r i p t i o n

none none none O x i d i z e d , r e d d i s h t o b r o y nexpanded sed imen t .

none none none P a r t l y expanded b l u e - g r a ys e d i m e n t E a s t Re e f .

none t r a c e none Someyha t e x p a n d e d c l a y .North o f U.S . M.M. #2.

none t r a c e none S o u t h of H a r r i s b u r g , c l a yq u a r r y , f l u f f y , g r a y t op u r p l e , expanded c l a y .

none 0 . 1 0 none Fres h s h a l e - l i k e m a t e r i a l ,o z s . / sou th of F i r e Clay H i l l 400t o n f e e t .

none 0 . 1 0 0.34% Fine , poydery, f r e s h s h a l e -o z s . / l i k e m a t e r i a l , n o r t h o ft o n U . S . M.M. #2 .

- 21 -



S e v e r a l x - r a y p a t t e r n s w e r e t a k e n o f t h eb e n t o n i t i c s h a l e s and c o m p a r e d w i t h a s t a n d a r dp a t t e r n f rom t h e B l a c k H i l l s b e n t o n i t e . Thermala n a l y s e s were a l s o r u n on s e v e r a l of t h e samples .Dr. C. J . Vi t a l i a n o ( p e r s o n a l communica t ion , 1949)e s t i m a t e s t h a t t h e s a m p l e s c o n t a i n e d up t o 60%

o r m o r e o f b e n t o n i t e .

T r a i l H i l l s a n d s t o n e

Brownish-red t o b r i c k - r e d s h a l e s and i n t e rbeddedf i n e - t o medium-gra ined s a n d s t o n e s c r o p o u t abovet h e F i r e Clay H i l l b e n t o n i t i c s h a l e s . L e n s e s o fp e b b l e c o n g l o m e r a t e s as much as one f o o t t h i c k ,c r o s s b e d d i n g , and minor r i p p l e marks , c h a r a c t e r i z ep a r t s of t h e T r a i l H i l l s a n d s t o n e s . The s a n d s t o n e sa r e f r i a b l e , b r i c k - r e d , an d a v e r a g e 310 f e e t i nt h i c k n e s s . L o c a l l y a b l e a c h i n g o f t h e r e d s a n d

s t o n e , p r o b a b l y by m e t e o r i c w a t e r s w h i c h h a v er e d u c e d t h e f e r r i c i r o n cement t o t h e f e r r o u s andt h e n d i s s o l v e d i t away, h a s r e s u l t e d i n r e d andw h i t e m o t t l i n g o r w h i t e b a n d i n g which c r o s s e s th eb e d d i n g and p a r a l l e l s l o c a l j o i n t s .

A d i s t i n c t i v e w h i t e t o g r a y i s h - w h i t e s i l i c eous l i m e s t o n e from s i x i n c h e s t o 1 . 5 f e e t i n t h i c kn e s s o c c u r s a t t h e t o p o f t h e l e d g e s a n d s t o n e .T h i s bed f o r m s an e a s i l y r e c o g n i z a b l e w h i t e bandi n t h e r e d s a n d s t o n e and i s t r a c e d r e a d i l y f o rs e v e r a l m i l e s . B e s t e x p o s u r e s a r e n e a r th e L e e d sThompson mine a r e a on t h e Whi te Ree f and on t h ef a c e of t h e Buckeye R e e f e a s t o f t h e Savage mine .The bed a l s o c r o p s o u t on t h e E a s t Ree f j u s t b elow t h e D u f f i n m i n e .

Ar e d , m e d i u m - g r a i n e d , f r i a b l e s a n d s t o n ew i t h min o r i n t e r b e d d e d b r i c k - r e d s h a l e s c r o p s ou t

above t h e s i l i c e o u s l i m e s t o n e . The s a n d s t o n e formsl e d g e s t h a t show r i p p l e marks and p r o m i n e n t c r o s sb e d d i n g . The b r i c k - r e d s a n d s t o n e s g r a d e i n t o a

f i n e t o medium-gra ined s a n d s t o n e wi th i n t e r b e d d e dp u r p l i s h s h a l e s .



G r e e n t o g r a y s h a l e s , l o c a l l y g r a d i n g t ob l u i s h g r e e n , o c c u r above t h e p i n k t o r e d s a n ds t o n e s . The s h a l e s r e a d i l y w e a t h e r and wou l dform g e n t l e s l o p e s , b u t t h e i r p o s i t i o n b e t w e e ntw o r e s i s t a n t s a n d s t o n e s c a u s e s t h em t o fo rmr a t h e r s t e e p s l o p e s , t h o u g h g e n t l e r t h a n t h o s eo f e i t h e r o f t h e s a n d s t o n e s above o r b e l o w. Thet h i c k n e s s o f t h e s h a l e s i s f a i r l y c o n s t a n t a t 25f e e t . Eas tward t oward t h e B u t t e Re e f and u n d e rl y i n g i t , t h e c o l o r c h a n g e s t o a d e e p maroonabove and green be low. On t h e E a s t Reef th e c o l o ro f t h e s h a l e s i s ma in ly g r a y.

An u n u s u a l bed o f j a s p e r 2 -6 i n c h e s t h i c k ,s t r o n g l y r e s e m b l i n g p e t r i f i e d wood, o c c u r s e i g h tf e e t below th e uppe r c o n t a c t o f th e s h a l e . Micros c o p i c s t u d y shows t h a t f i n e - g r a i n e d q u a r t z h a sr e p l a c e d th e s h a l e . The bed seldom c r o p s o u t , b u tt h e d i s t i n c t i v e re d wavy banded f l o a t d e m o n s t r a t e si t s p r e s e n c e over wide a r e a s .

S i l v e r Reef Sands tone Member

Owing t o i t s d i s t i n c t i v e appea rance and p o s it i o n n e a r t h e c e n t e r o f t h e measured s e c t i o n , t h e

S i l v e r R e e f s a n d s t o n e i s a r b i t r a r i l y s e l e c t e d ast h e member d i v i d i n g t h e u p p e r C h i n l e f rom t h el owe r Chin l e i n th e a r e a d e s c r i b e d i n t h i s r e p o r t .The S i l v e r Reef s a n d s t o n e c o n t a i n e d a l l t h e knowncommerc i a l q u a n t i t i e s o f s i l v e r which were minedi n th e p a s t i n t h e H a r r i s b u rg ( S i l v e r Reef) Miningd i s t r i c t . Copper c a r b o n a t e s and u ran ium-vanad iumm i n e r a l showings a l s o a re main ly r e s t r i c t e d t o t h i smember of t he Ch in l e .

R e e s i d e and B a s s l e r (p . 6 2 , 1922) n o t e d t h eS i l v e r R e e f s a n d s t o n e i n a s e c t i o n m e a s u r e d onS m i t h ' s m e s a , t h r e e m i l e s n o r t h of Vi r g i n C i t y ,U t a h , and 12 m i l e s e a s t o f S i l v e r R e e f :

- 23 -



"In a l l " area only one s e c t i o n of the Chin lef o r m a t i o n was measured , though th e fo rma t i o n i s a prominen t member of th e s t r a

t i g r a p h i c s e r i e s . Thi s s e c t i o n ( n o . 1 3 ,p . 73) i s n e a r Vi r g i n C i t y and a g g r eg a t e s 995 f e e t i n t h i c k n e s s . No l i m es t o n e s were o b s e r v e d . The b a s a l memberc o n s i s t s o f 260 f e e t o f v a r i e g a t e d ,b l u i s h - g r a y , g r e e n i s h - g r a y, mauve, r e d ,and r a r e l y brown "gumbo" c l a y s h a l e andc o n t a i n s f o s s i l wood. Upon t h i s r e s t s25 f e e t of v a r i a b l e c o a r s e a r k o s i c - c r o s s

b e d d e d s a n d s t o n e b a n d e d w i t h g r a y ,w h i t e , a n d mauve c o n t a i n i n g f o s s i lwood . T h i s s a n d s t o n e i s o v e r l a i n by420 f e e t o f b r i c k - r e d s h a l e and s a n ds t o n e , f o r m i n g a s l o p e . Next comes a

m a s s i v e m e d i u m - g r a i n e d c r o s s - b e d d e dr i p p l e - m a r k e d , c l i f f - f o r m i n g mauve s a n ds t o n e 90 f e e t t h i c k . Above t h i s s a n ds t o n e l i e s a b o u t 200 f e e t of b r i c k - r e dt o d e e p - r e d s h a l e and s a n d s t o n e .

The banded g r a y, w h i t e , and mauve s a n ds t o n e i s l o c a l l y known as t h e " S i l v e rR e e f " s a n d s t o n e , a s i t i s s a i d t o bet h e zone which i n th e S i l v e r R e e f , n e a rLeeds , Utah , c o n t a i n s t h e f o s s i l l o g s imp r e g n a t e d w i t h s i l v e r m i n e r a l s t h a t i nt h e e i g h t i e s suppor t ed s e v e r a l f l o u r i s hin g mining e n t e r p r i s e s . "

The p o s i t i o n of t h e S i l v e r Reef s a n d s t o n ei s o n l y 260 f e e t above t h e b a s e o f t h e C h i n l ef o r m a t i o n a c c o r d i n g t o t h e s e a u t h o r s , y e t i nt h e S i l v e r Reef a r e a th e c o r r e l a t i v e s a n d s t o n e i s620 f e e t above t h e b a s e . I t w i l l be n o t e d t h a tt h e i r " a r k o s i c s a n d s t o n e , " o r s u p p o s e d S i l v e r

R e e f s a n d s t o n e , l i e s a b o u t t h e same d i s t a n c eabove t h e b a s e o f t h e Chin le as t h a t measured byt h e w r i t e r f o r t h e a r k o s i c bed i n t h e H a r t l e ys h a l e s and s a n d s t o n e s which a l s o c o n t a i n prominen tf o s s i l l o g s . The S i l v e r Reef s a n d s t o n e i n t h eS i l v e r R e e f a r e a i s a t a p p r o x i m a t e l y t h e sameh o r i z o n as th e "mauve c r o s s - b e d d e d , r i p p l e - m a r k e d



s a n d s t o n e " of R e e s i d e and B a s s l e r . The s t r o n gp o s s i b i l i t y e x i s t s t h a t th e S i l v e r Reef s a n d s t o n eh a s changed i n c o l o r and l i t h o l o g y somewhat t ot h e e a s t and t h a t t h e same e r r o r h a s b e e n madeby them a s b y B a l l ( 1 9 2 0 ) , C r a n e ( 1 9 2 0 ) , andB u t l e r ( p . 587 , 1920) i n c o r r e l a t i n g t h e s a n ds t o n e of t h e B u t t e ( S i l v e r Reef s a n d s t o n e ) Reefw i t h t h e a r k o s i c bed ( s e e f i g u r e 1 ) .

For conven ience o f d e s c r i p t i o n and a l s o f o rmapping p u r p o s e s t h e S i l v e r Ree f s a n d s t o n e h a sbeen s u b d i v i d e d i n t o th e Leeds s a n d s t o n e , namedf o r th e e x p o s u r e s n e a r th e Leeds mine , which i nc l u d e s m a i n l y w h i t e t o b u f f , f i n e - t o mediumg r a i n e d s a n d s t o n e beds w i t h i n t e r b e d d e d s h a l e s ;and an ove r ly ing l a v e n d e r, f i n e - t o medium-gra ineds a n d s t o n e c a l l e d t h e Tecumseh s a n d s t o n e f o r t h ee x p o s u r e s on Teoumseh H i l l .

Leeds S a n d s t o n e

The Leeds s a n d s t o n e l o c a l l y i s unconformable

on th e u n d e r l y i n g s h a l e s . The t h i c k n e s s v a r i e sfrom p l a c e t o p l a c e , b u t i n th e main min ing a r e ai t r e a c h e s 60 f e e t . The sands tone wea the r s mainl y w h i t e and b u f f t o brown, and s t a n d s o u t as ap r o m i n e n t l e d g e maker. I t i s f i n e - g r a i n e d , anda l i t t l e c o a r s e - g r a i n e d muscovi te mica may l o c a l l ybe prominent on th e bedding p l a n e s .

St ream c r o s s - b e d d i n g i s p r o m i n e n t i n many

p l a c e s . L o c a l l y c h a n n e l s w i t h i n t h e s a n d s t o n ea re r e c o g n i z a b l e . R i p p l e marks a re r a r e , t hougha c u r r e n t t y p e was n o t e d n e a r H a r r i s b u r g . Thes a n d s t o n e beds w i t h i n th e member r a n g e f rom mass i v e 1 5 - f o o t beds down t o t h i n , p l a t y s a n d s t o n e sand l o c a l l y a re h i g h l y c r o s s - b e d d e d . L e n t i c u l a r ,i n t e r b e d d e d , da rk g ray t o green o r l o c a l l y maroons h a l e s may be p r e s e n t . The s h a l e s a r e u s u a l l yn o t a b l y s l i c k e n s i d e d and show a g l i s t e n i n g l u s t e r

on th e f r e s h f r a c t u r e s u r f a c e . The s l i c k e n s i d e ds h a l e s , c a l l e d " s o a p s t o n e s " by t h e m i n e r s , seldomc r o p o u t s u f f i c i e n t l y t o p e r m i t mapping b u t maybe more t h a n s i x f e e t i n t h i c k n e s s . Commonlyt h e y t h i n a b r u p t l y a long b o t h t h e s t r i k e and th e

- 25 -



P l a t e I I I . TYPES OF CROSS-BEDDING

A. L o c a l d e l t a f o r e s e t t ype of c r o s s - b e d d i n g ,

B u t t e Reef , n e a r Leeds , Utah .

B. Mass ive c h a n n e l - f i l l c r o s s - b e d d i n g ,White Reef , n e a r L e e d s , Utah .



P l a t e IV. TYPES OF CROSS-BEDDING

A. Thin-bedded c h a n n e l - f i l l c r o s s - b e d d i n gWhite Reef , n e a r Leeds , Utah .

B. Flow c r o s s - b e d d i n g , s o u t h of Savage S h a f t ,Buckeye Reef , n e a r Leeds , Utah .

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d i p . The s a d d l e a t t h e A.S . & R. s h a f t on t h eWhite R e e f i s t h e r e s u l t o f t h e w e a t h e r i n g of a" s o a p s t o n e " b e d . Where n o t b a d l y w e a t h e r e d , th ebeds may show f i n e c r o s s - l a m i n a t i o n s .

S a n d s t o n e s c o n t a i n i n g c l a y g a l l s and b a l l so c c u r b o t h above and below t h e s h a l e s . L o c a l l yt h e y may b e s u f f i c i e n t l y a b u n d a n t t o form c l a yb a l l c o n g l o m e r a t e s . The c l a y b a l l s a r e u n u s u a li n t h a t t h e y r a n g e f rom as s m a l l as o n e - f o u r t hi n c h i n d i a m e t e r or l e s s t o more t h a n f o u r f e e t .The b e d s e n c l o s i n g t h e b a l l s a re as much as f o u ro r more f e e t i n t h i c k n e s s ( s e e P l a t e V I, A ).The Leeds , Cobb, and McNally mines show a l l g r a da t i o n s of t h e s e as do many p i t s a long th e f a c e ofb o t h t h e Buckeye and White r e e f s .

F o s s i l r u s h e s , r e e d s , p a r t s o f p e t r i f i e dt r e e s , and r a r e l y l o g s t o 30 f e e t i n l e n g t h a r efound i n t h e Leeds s a n d s t o n e . No o t h e r t y p e s off o s s i l s have been d i s c o v e r e d . L o c a l l y, th e f o s s i lr e m a i n s may be r e p l a c e d by s i l v e r - c h l o r i d e , c o pp e r c a r b o n a t e , i r o n and copper s u l f i d e s , a n d / o r u ran ium-vanad ium m i n e r a l s . C o n c r e t i o n a r y n o d u l e so f i r o n o x i d e w i t h some p y r i t e , and c o p p e r s u lf i d e as much as 1 i n c h o r more i n d i a m e t e r a l s oo c c u r i n t h e s a n d s t o n e .

Tecumseh S a n d s t o n e

The Tecumseh sands tone abou t 35-45 f e e t t h i c k ,i n p l a c e s i s unconformable on th e Leeds s a n d s t o n e .I t i s t h i n - b e d d e d t o mass ive and commonly l a v e n d e rc o l o r e d . I m p r e s s i o n s of r u s h e s and r e e d s o c c u ron t h e b e d d i n g s u r f a c e s , b u t i n l e s s e r abundancet h a n i n t h e whi t e and b u f f sands tones be low. Musc o v i t e mica i s common on t h e b e d d i n g p l a n e s . Ab u f f t o ye l low s a n d s t o n e , prominen t ly i r o n - s t a i n e dand as much as s i x f e e t t h i c k , o c c u r s n e a r th emidd le o f th e Tecumseh s a n d s t o n e on Tecumseh H i l land a l s o a l o n g t h e e a s t f a c e o f t h e Whi te Ree fn e a r t h e Thompson m i n e .

28



In t h e main min ing a r e a t h e l a v e n d e r s a n ds t o n e s r e a c h t h e i r g r e a t e s t t h i c k n e s s on TecumsehH i l l v h e r e t h e a v e r a g e i s a p p r o x i m a t e l y 35-40f e e t . N o r t h , n e a r t h e Barbee m i n e , t h e t h i c kness i s 30 f e e t or l e s s . On th e E a s t Reef a t th eDuff in mine a s e c t i o n shovs about 50 f e e t of l a vender sands tone . D i r e c t l y e a s t of Leeds th e Leedss a n d s t o n e d e c r e a s e s i n t h i c k n e s s . The Tecumsehi n c r e a s e s and on th e nose of th e Vi rg i n a n t i c l i n ei s th e most prominen t bed .

D e p o s i t i o n a l H i s t o r y of S i l v e r Reef Sands tone

As th e l o c u s of o re d e p o s i t i o n i s v i t h i n th eS i l v e r R e e f s a n d s t o n e , a d e t a i l e d s t u d y of t h emember and i t s pr imary f e a t u r e s i s e s s e n t i a l . Theabundance and s i z e of some of t h e c l a y b a l l s , t h enumerous c l a y g a l l s , s a n d s t o n e l e n s e s , t h e l e s sabundant i n t e r b e d d e d , l e n t i c u l a r s h a l e s , and t h ep r o m i n e n t c r o s s - b e d d i n g a r e among t h e most d i st i n c t i v e pr imary f e a t u r e s observed . The f i n e t e xt u r e of t h e s a n d s t o n e and t h e l o c a l abundance o ff o s s i l r e m a i n s o f p r o b a b l e r u s h e s and r e e d s andp a r t s of t r e e s a re a l s o o f s p e c i a l n o t e .

A c r i t i c a l q u e s t i o n may be a s k e d : I s t h i ssands tone member of th e Chin le fo rma t ion of mar ineo r c o n t i n e n t a l o r i g i n ? Among g e o l o g i s t s of t h es o u t h v e s t e r n Uni ted S t a t e s th e o r i g i n of th e T r ia s s i c C h i n l e "Red Beds" h a s b e e n a s u b j e c t o fl i v e l y d i s c u s s i o n and d e b a t e . E. B. Branson (pp .607-630 , 1927) s u g g e s t e d a mar ine o r i g i n f o r muchof th e u p p e r T r i a s s i c of S o u t h e r n Utah . R e e s i d ei n a l a t e r a r t i c l e (p . 4 8 , 1929) s u p p o r t e d t h ei d e a of a c o n t i n e n t a l o r i g i n . The c n n s e n s u s ofl a t e r v r i t e r s - - G i l l u l y (p . 89 . 1929) Gregory andMoore (p . 57, 1931) , Baker (p . 40, 1933) a t . a l . -i s t h a t th e Chin le beds a re of c o n t i n e n t a l o r i g i n .As t h e S i l v e r Reef s a n d s t o n e l i e s s t r a t i g r a p h ic a l l y n e a r t h e c e n t e r o f t h e C h i n l e f o r m a t i o n ,t h e r e i s s t r o n g i n c l i n a t i o n t o i n c l u d e i t v i t ho t h e r

members anda s c r i b e t o i t

a c o n t i n e n t a lo r i g i n . Hovever, more ev idence t han j u s t p o s i t i o ni n a c o n t i n e n t a l s e q u e n c e i s n e e d e d . B r i e f l ysummarized, the l a c k of mar ine fOSSi l s , t he abundance of p a r t s of t r e e s , remains of a n c i e n t r u s h e s

- 29 -



P l a t e V. SEDIMENTARY ROCK TYPES

A. C o n t a c t o f Leed s and Tecumseh s a n d s t o n e

j u s t n o r t h of L e e d s , U t a h .

B. D u ff i n s a n d s t o n e , s o u t h o f D u ff i n m i n e ,E a s t R e e f , n e a r L e e d s , U t a h .

30



P l a t e VI. SEDIMENTARY ROCK TYPES

A. F l a t t e n e d c l a y b a l l s i n Leeds s a n d s t o n e ,White Reef , n e a r L e e d s , Utah .

B. P i t t e d w e a t h e r i n g s a n d s t o n ea t base of Buckeye Reef .

- 31 -



II!!

and r e e d s , s t r eam c r o s s - b e d d i n g ( d i s c u s s e d be low) ,c h a n n e l i n g o f t h e u n d e r l y i n g s h a l e s , c l a y g a l l s ,c l a y b a l l s , and r a p i d l e n s i n g o f i n d i v i d u a l s a n d

s t o n e and s h a l e beds a l l s t r o n g l y s u g g e s t a c o n t in e n t a l o r i g i n f o r th e S i l v e r Reef s a n d s t o n e .

Of t h e t h r e e i m p o r t a n t t r a n s p o r t i n g a g e n t s :w i n d , w a t e r and i c e , which may have d e p o s i t e d th es a n d s t o n e , i c e i s d i r e c t l y exc luded because of ther a t h e r p e r f e c t s o r t i n g of t h e s e d i m e n t s , s t r a t if i c a t i o n , s t r e a m c h a n n e l s , e t c . Wind and w a t e rc o u l d h a v e b e e n i m p o r t a n t i n t h e d e p o s i t i o n oft h e s a n d s t o n e , b u t t h e above f e a t u r e s a r e m o s tt y p i c a l o f f l u v i a t i l e d e p o s i t s and t h e i r r e g u l a rc r o s s - b e d d i n g o f t e n c i t e d as e v i d e n c e f o r e o l i a no r i g i n i s l a c k i n g . I t i s conc luded t h a t t h e s a n ds t o n e member was d e p o s i t e d by s t r e a m s .

O t h e r q u e s t i o n s t h a t a r i s e a r e : Was t h e r ea s p e c i a l d i r e c t i o n o f f l o w o f t h e s t r e a m o rs t r e a m s , an d i f s o , w h a t d i r e c t i o n ? F i n a l l y ,u n d e r what e n v i r o n m e n t a l c o n d i t i o n s was th e s a n ds t o n e depos i t ed? The f i r s t q u e s t i o n can be answeredw i t h a f a i r d e g r e e o f c e r t a i n t y ; t h e l a t t e r i ssomewha t s p e c u l a t i v e .

The a b u n d a n c e o f T r i a s s i c s t r e a m c h a n n e l si n t h e S i l v e r R e e f s a n d s t o n e i n th e main m i n i n gd i s t r i c t and t h e d i s t i n c t i v e t y p e s of c r o s s bedsa s s o c i a t e d w i t h them a r e o f s p e c i a l i n t e r e s t .Many w r i t e r s h a v e d e s c r i b e d d i f f e r e n t v a r i e t i e so f c r o s s - b e d d i n g i n o t h e r l o c a l i t i e s . P r o b a b l ym o s t f a m i l i a r t o g e o l o g i s t s a r e t h e s u m m a r i e so f Grabau ( p p . 701-704, 1913) and Lahee (pp . 80-88, 1941) . O t h e r work on t h i s s e d i m e n t a r y f e at u r e has been p u b l i s h e d by Andree (p . 377, 1915) ,Knight (pp. 1-82 ,1929) , Andersen (pp. 21-31, 1931),McKee (pp. 64-81, 1939), S c o t t (pp. 165-172, 1949),

and6 ~ h e r s .

P e t t i j o h n (pp . 132-134, 1949( i n h i sr e c e n t book summarizes many o f th e i m p o r t a n t t y p e swhich have been d e s c r i b e d .

32



From d e s c r i p t i o n s i n t h e l i t e r a t u r e i t i sobvious t h a t no g e n e r a l agreement has been r eachedas t o t h e p r o p e r name f o r th e d i f f e r e n t t y p e s ofs t r e a m c r o s s - b e d d i n g . C r o s s l a m i n a t i o n , f a l s e

bedd ing ,c u r r e n t

b e d d i n g ,c r o s s

b e d d i n g ,have a l l

been used t o d e s c r i b e t h i s s e d i m e n t a r y f e a t u r e .According t o Fay (p . 193 , 1930) c r o s s - b e d d i n g i s" l a m i n a t i o n i n s e d i m e n t a r y r o c k s , c o n f i n e d t os i n g l e b e d s and i n c l i n e d t o th e g e n e r a l s t r a t i -

f i c a t i o n . " Thi s i s i n c o n t r a s t t o Ander sen whow o u l d r e s t r i c t t h e t e rm t o a d e f i n i t e t y p e o fi n c l i n e d b e d d i n g . S i n c e t h e t e rm c r o s s - b e d d i n ghas been used e x t e n s i v e l y i n American l i t e r a t u r e ,

th e d e f i n i t i o n of Fay i s accep ted f o r t h i s r e p o r tand m o d i f y i n g a d j e c t i v e s a r e added t o d e s c r i b et h e v a r i o u s t y p e s .

I n t h e S i l v e r Reef a r e a a t l e a s t two andp o s s i b l y t h r e e d i s t i n c t i v e t y p e s o f c r o s s - b e d d i n ga r e r e c o g n i z a b l e : (a ) The l o c a l d e l t a f o r e s e tc r o s s - b e d d i n g of McKee (p . 7 8 , 1 9 3 9 ) ; (b) Channelf i l l c r o s s - b e d d i n g ; (c ) The t h i r d t ype i s a modi

f i e d fo rm o f ( a ) w h i c h shows p l a s t i c f l o w o fth e l o c a l d e l t a f o r e s e t c r o s s - b e d d i n g j u s t a f t e rd e p o s i t i o n . The t e rm f low c r o s s - b e d d i n g i s s u gg e s t e d f o r t h i s v a r i e t y .

The l o c a l d e l t a f o r e s e t bedd ing c o n s i s t s o fa s e r i e s o f t r u n c a t e d , g e n t l y i n c l i n e d beds d i pp i n g 30 d e g r e e s i n one d i r e c t i o n an d showing ar a t h e r c o n s t a n t s t r i k e where e x p o s e d . O u t c r o p s

showing t h i s t y p e may be as much as 100 f e e t o rmore i n l e n g t h . The angle of d ip i s g r e a t e s t nea rt h e t o p , and more g e n t l e downward u n t i l f i n a l l yan a l m o s t t a n g e n t i a l c o n t a c t o c c u r s w i t h t h e u nd e r l y i n g b e d s . The l e n g t h o f t h e i n c l i n e d b e d smay be as much as 10 f e e t or more. The l o c a l d ~ l t a

f o r e s e t t y p e i s w e l l exposed on t h e B u t t e R e e fj u s t wes t of Leeds . Though no c o m p l e t e h o r i z o nt a l s e c t i o n was o b s e r v e d , t h e c r o s s - b e d d i n g a p

p a r e n t l y d i s a p p e a r s a long t h e s t r i k e f o r p a r t l yexposed p r o j e c t e d beds f a i l e d t o show t h e c r o s sb e d d i n g . The c r o s s - b e d d i n g p r o b a b l y formed i n as t a n d i n g body of w a t e r as f o r e s e t beds of a s m a l l

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d e l t a . ( P l a t e I I I , A) c l e a r l y shows t h e t a ng e n t i a l r e l a t i o n s h i p on t h e u n d e r l y i n g bed anda p p a r e n t t r u n c a t i o n o f th e upper p a r t by th e overl y i n g s a n d s t o n e s .

The c h a n n e l f i l l c r o s s - b e d d i n g ( s e e P l a t e sI I I , B and IV, A) appea r s t o r e p r e s e n t th e f i l l i n gof a fo rmer s t ream c h a n n e l c u t i n t o th e u n d e r l y i n gsands tone beds . McKee (pp . 78-79 , 1939) d e s c r i b e sa s i m i l a r type on th e Colorado d e l t a , b u t h i s d e sc r i p t i o n a p p l i e s t o c h a n n e l s i n muds, r a t h e r t h a ns a n d s t o n e . As shown i n t h e f i g u r e , t h e beds i nt h e f i l l e d c h a n n e l may r a n g e from a f r a c t i o n o fan i n c h t o more t h a n a f o o t t h i c k . In one p l a c ea m a s s i v e a p p e a r i n g s a n d s t o n e more t h a n s e v e nf e e t i n t h i c k n e s s f i l l e d one o f t h e s e c h a n n e l s .

The t h i n n e r b e d s a p p r o a c h p a r a l l e l i s m w i t ht h e w a l l s o f t h e c h a n n e l , whereas t h e uppe rmos tc h a n n e l - f i l l b e d s may g r a d u a l l y c o a l e s ~ ew i t ht h e o v e r l y i n g s a n d s t o n e s . Only t h e beds be tween

t h e f i r s t and l a s t d e p o s i t e d i n th e c h a n n e l s maybe t r u n c a t e d by t h e o v e r l y i n g s e d i m e n t s . In manyp l a c e s , however, most o f them show t r u n c a t i o n byt h e o v e r l y i n g s a n d s t o n e b e d s . The c h a n n e l - f i l l sr a n g e f rom a few f e e t t o o v e r 300 f e e t i n w i d t h .The l e n g t h of t h e c h a n n e l s i s unknown s i n c e onlys m a l l p o r t i o n s of th e c h a n n e l d i r e c t i o n were r ec o g n i z e d o r e x p o s e d . I t i s i m p o r t a n t t o n o t et h a t t h e c h a n n e l - f i l l c r o s s - b e d d i n g i s most app a r e n t i n th e s m a l l e r c h a n n e l s . The l a r g e r onesmay show such a s l i g h t d i v e rg e n c e of bedding fromth e e n c l o s i n g beds as t o be a lmos t u n r e c o g n i z a b l e .I t n e c e s s a r i l y f o l l o w s t h a t t h e w i d e r t h e fo rmerc h a n n e l , t h e c l o s e r th e beds approach t o p a r a l l e lism w i t h t h e e n c l o s i n g b e d s , t hough l o c a l v a r i at i o n s may o c c u r. Another f a c t o r t o be c o n s i d e r e di s l i t h o l o g y . I f a c h a n n e l i s c u t i n t o m a s s i v ew h i t e s a n d s t o n e and f i l l e d w i t h a s i m i l a r v a r i e t yo f s a n d s t o n e g r e a t d i f f i c u l t y may be e x p e r i e n c e di n r e c o g n i z i n g t h e f o r m e r c h a n n e l . G e n e r a l l y ,h o w e v e r, s l i g h t c o l o r and t e x t u r a l d i f f e r e n c e si n t h e s a n d s t o n e s d i s t i n g u i s h t h e c h a n n e l s .

34



In t h e Leeds m i n e , a c h a n n e l - f i l l s a n d s t o n eg rades l a t e r a l l y i n t o c l a y b a l l s , and f i n a l l y i n t oa l t e r n a t i n g s a n d s t o n e s and s h a l e s . The g e o l o g i cs e t t i n g s u g g e s t s a once c o n t i n u o u s d e p o s i t o fa l t e r n a t i n g c l a y s and sand t h rough which a channe lvas c u t by a s t r eam and l a t e r f i l l e d by reworkedc l a y and a d d i t i o n a l s a n d .

C l o s e l y spac e d measured s e c t i o n s a l o n g b o t hth e Buckeye and White r e e f s i n th e mining a r e a shovan i n t e r f i n g e r i n g o f l e n s e s or c h a n n e l - f i l l s o fs a n d s t o n e b e d s . Both th e c h a n n e l - f i l l and l o c a ld e l t a f o r e s e t t ypes of c r o s s - b e d d i n g v e r e observedv i t h i n t h e s e l e n s e s .

The t h i r d type of c r o s s - b e d d i n g i s r ecogn izedas a s p e c i a l v a r i e t y of l o c a l - d e l t a f o r e s e t bedd ingupon which a n o t h e r s t r u c t u r e h as been super imposedf o l l o v i n g d e p o s i t i o n . In t h i s r e s p e c t i t may w e l lbe t e r m e d a s e c o n d a r y f e a t u r e , b u t i t s a l m o s tc o i n c i d e n t f o r m a t i o n a t t h e t i m e o f d e p o s i t i o nj u s t i f i e s a d e s c r i p t i o n h e r e . A p p a r e n t l y s m a l l

f o r e s e t c r o s s - b e d s were d e p o s i t e d . J u s t a f t e rd e p o s i t i o n subaqueous movement o f t h e s e d i m e n t st ook p l a c e and t h e c r o s s - b e d d i n g was f o l d e d p l a st i c a l l y i n t h e d i r e c t i o n o f d i p o f t h e f o r e s e tb e d s . These s m a l l f o l d s may have been t h e r e s u l to f l a t e r beds b e i n g d e p o s i t e d n e a r t h e a n g l e o fr e p o s e o f t h e s e d i m e n t s . A s l i g h t s h i f t i n t h el o a d by s lumping o r s l i g h t t i l t i n g cou ld have r es u l t e d i n th e p l a s t i c f low o f t h e v a t e r - s a t u r a t e dc r o s s - b e d s . The f o l d i n g i s a lmos t i s o c l i n a l ( P l a t eIV , B ) . Examples o f t h i s t y p e o f c r o s s - b e d d i n ga r e s h o v n i n t h e open s u r f a c e s t o p e 1300 f e e ts o u t h o f t h e S a v a g e s h a f t .

S t r e a m D i r e c t i o n s

The d i r e c t i o n o f maximum i n c l i n a t i o n o f t h el o c a l - d e l t a f o r e s e t t y p e o f c r o s s - b e d d i n g wasc o n s i d e r e d t o be t h e d i r e c t i o n o f t h e o r i g i n a lc u r r e n t d e p o s i t i n g th e s a n d . I n some l o c a l i t i e st h e s t r i k e o f t h e c r o s s - b e d d i n g c o u l d be d e t e rmined . The s t r eam d i r e c t i o n a t t h e s e p o i n t s wast a k e n a t 90 0 t o t h e s t r i k e i n t h e d i r e c t i o n o f

- 35 -



i n c l i n a t i o n o f t h e c r o s s - b e d d i n g . I n t h e c a s eo f t h e c h a n n e l - f i l l c r o s s - b e d d i n g , t h e t r e n d o ft h e s t r e a m c h a n n e l was d e t e r m i n e d by t h e t r e n d

o f t h e a x i s of th e c h a n n e l , b u t th e a c t u a l c u r r e n td i r e c t i o n c o u l d n o t be a s c e r t a i n e d e x c e p t wherec r o s s - b e d d i n g o f f o r e s e t t y p e was a l s o p r e s e n t .

I n g e n e r a l , t h e d i r e c t i o n o f i n c l i n a t i o n o ft h e c r o s s - b e d d i n g i s f a i r l y uni form i n th e mininga r e a . As c an be r e a d i l y u n d e r s t o o d , n e i t h e r t h es c a l e of t h e map nor t h e c o n t i n u i t y of beds al lowc o n t r o l a t one h o r i z o n w i t h i n t h e S i l v e r R e e f

s a n d s t o n e . The s t r e a m d i r e c t i o n s shown on t h emap o c c u r a t d i f f e r e n t s t r a t i g r a p h i c p o s i t i o n sw i t h i n t h e 80 t o more t h a n 100 f e e t o f S i l v e rR e e f s a n d s t o n e . The f o r m e r s t r e a m o r s t r e a m sg e n e r a l l y f lowed N.30 o W. L o c a l l y , s o u t h e a s t oft h e Savage Mine, t h e d i r e c t i o n changes t o a lmos te a s t - w e s t and s o u t h w a r d . The s c a r c i t y of c r o s sb e d d i n g o r s t r e a m c h a n n e l s i n a d i r e c t i o n o t h e rt h a n t h e main t r e n d s u g g e s t s a f a i r l y u n i f o r md e p o s i t i o n a l h i s t o r y f o r t h e s a n d s t o n e . Modi fyi n g f a c t o r s o f p o s s i b l e f l o o d p l a i n e n v i r o n m e n tp r o b a b l y e x i s t e d . P l a t e I I shows a g e n e r a l i z e dd i s t r i b u t i o n o f r e a d i n g s and s t r eam d i r e c t i o n i nt h e min ing a r e a . While i t i s r e a l i z e d t h a t someo f t h e i n t e r p r e t a t i o n s a r e d o u b t f u l b e c a u s e o fp o o r e x p o s u r e s , s t i l l t h e t r e n d i s r e m a r k a b l yc o n s t a n t f o r t h o s e shown. I t i s r e g r e t t e d t h a tmost o f t h e l a r g e mines i n t h e d i s t r i c t a re i na c c e s s i b l e and t h a t d e t a i l e d work on t h e c r o s sb e d d i n g had t o be l i m i t e d main ly t o s u r f a c e o u tc r o p s .

D u ff i n S a n d s t o n e and S h a l e s

S t r a t i g r a p h i c a l l y above th e S i l v e r Reef sands tone and s e p a r a t e d from i t by l o c a l unconfo rmi t i e si s a 427 f o o t sequence of medium t o coa r se g ra ined ,b r i c k - r e d sands tones wi th in te rbedded purp le s h a l e s .C r o s s - b e d d i n g i s l o c a l l y p r o m i n e n t . Near t h eC a l i f o r n i a , Barbee and Walke r, and Thompson minesa c l a y p e b b l e cong lomera t e as much as one f o o t i n



t h i c k n e s s l i e s j u s t above th e u p p e r c o n t a c t of th eTecumseh s a n d s t o n e . The c l a y p e b b l e s a r e a sl a r g e as h a l f an i n c h i n d i a m e t e r , and p r o b a b l yr e p r e s e n t t h e b e g i n n i n g o f d i f f e r e n t c o n d i t i o n so f s e d i m e n t a t i o n .

West o f th e McNal ly mine t h e r e d s a n d s t o n eand s h a l e s i n c l u d e a t h i n ~ h i t e s a n d s t o n e 50 f e e tabove th e l o ~ e rc o n t a c t . The ~ h i t e s a n d s t o n e i sno t con t inuous and l e n s e s l a t e r a l l y and v e r t i c a l l yi n t o th e r e d s a n d s t o n e s above and below i t . Th i ssame bed may be r e p r e s e n t e d on t h e Buckeye R e e fwes t o f t h e C a l i f o r n i a Mine by a w h i t e , d i s c o nt i n u o u s s a n d s t o n e r a n g i n g f rom a few i n c h e s t of o u r or more f e e t i n t h i c k n e s s . The bed i s b a d l ys h e a r e d . The whi t e s a n d s t o n e s t r o n g l y r e s e m b l e st h e Leeds s a n d s t o n e i n t e x t u r e and c o l o r . T h i ssame bed was n o t obse rved on th e E a s t Reef . Because o u t c r o p s a r e v e r y p o o r n e a r S i l v e r R e e f , a

s e c t i o n of Chin le above th e S i l v e r Reef s a n d s t o n ewas measured e a s t o f t h e D u ff i n Mine. I t showedt h e f o l l o w i n g :

Measured S e c t i o n o f Upper Chin le F o r m a t i o n500 f e e t s o u t h o f D u ff i n Mine

Thicknes s D e s c r i p t i o n

Navajo s a n d s t o n e .

65' B r i c k - r e d , medium-gra ined s a n d s t o n e s , minorr e d s h a l e s , s l o p e ~ e a t h e r i n g .

1 2 ' B r i g h t - r e d , medium-gra ined , l edge -make r s a n ds t o n e .

75 ' P a r t l y covered . Exposed s e c t i o n main ly d a r kr e d s h a l e s , some q u i t e s a n d y. Near b a s etwo beds t h i n gray a r g i l l a c e o u s s a n d s t o n e .

1 8 ' B r i c k - r e d s h a l e s , s l o p e w e a t h e r i n g . B a s e ,p i t t e d , f r i a b l e , g r a y, medium-gra ined s a n d

s tone s i x i nches t h i c k .2 2 ' Top, m o t t l e d g r a y and r e d sandy s h a l e f o u ri n c h e s t h i c k , l e d g e - f o r m e r . S ix f e e t b el ow, b r i c k - r e d , f r i a b l e s a n d s t o n e . Base ,s l o p e w e a t h e r i n g b r i c k - r e d s h a l e s .

- 37 -



6 0 ' S e r i e s of b r i c k - r e d s h a l e s , s l o p e w e a t h e r i n g ;n e a r base t h r e e beds two t o f o u r inches t h i c kof gray c a l c a r e o u s s h a l e .

7 3 ' Main ly b r i c k - r e d s h a l e s . C e n t e r of u n i t twoi n c h bed g r a y s h a l e , r e d s h a l e s b e l o w.At b a s e a w e l l - j o i n t e d , p i t t y w e a t h e r i n gs a n d s t o n e 2 1 / 2 ' t h i c k .

2 5 ' Main ly s a n d y, b r i c k - r e d s h a l e s w i t h no d i st i n c t i v e b e d s . At base s i x i n c h e s o f w h i t e ,f i n e - g r a i n e d s a n d s t o n e .

6 2 ' P r e d o m i n a n t l y r e d s h a l e s , some m i n o r s a n ds t o n e ; 2 1 / 2 ' p ink sandy s h a l e 20 f e e t above

b a s e .1 5 ' Red s h a l e s , s o i l - w e a t h e r i n g , 10 f e e t t h i c k ,

5 ' o f p i n k t o r e d s a n d s t o n e l e d g e - m a k e r a tb a s e .

S i l v e r Reef s a n d s t o n e member.

4 2 7 ' To t a l

Nava jo ( J u r a s s i c ? ) S a n d s t o n e

The l i m i t o f a r e a l mapp ing was a r b i t r a r i l yt a k e n a s t h e b a s e o f t h e m a s s i v e , c l i f f - f o r m i n g ,r e d Navajo s a n d s t o n e . A s e c t i o n was n o t measu red ,b u t a g e n e r a l i z e d s e c t i o n above t h e D u ff i n s h a l e sand s a n d s t o n e s would show a b r i c k - r e d , m a s s i v es a n d s t o n e l e d g e - m a k e r n e a r t h e b a s e , f o l l o w e d bys t r o n g l y e o l i a n c r o s s - b e d d e d r e d and b r i c k - r e ds a n d s t o n e s . R e e s i d e and B a s s l e r ' s d e s c r i p t i o n( p . 6 3 , 1922) i s c h a r a c t e r i s t i c of t h i s prominen ts a n d s t o n e :

I n Wa s h i n g t o n Coun ty, U t a h , t h e r el i e s above t h e C h i n l e f o r m a t i o n a m a ss i v e c r o s s - b e d d e d s a n d s t o n e t h a t i s l o

c a l l y a l l r e d b u t i n mos t p l a c e s r e d i nt h e l o w e r p a r t and w h i t e above t h e r e dp o r t i o n m a k i n g up o n e - h a l f o r more oft h e u n i t . The l o w e r p a r t c h a r a c t e r i st i c a l l y fo rms a r c h e s , and th e u p p e r p a r tw e a t h e r s t o r o u n d p i n n a c l e s and domes •• . • o n l y one m e a s u r e m e n t o f t h e t h i c k -



n e s s of th e s a n d s t o n e was a t t e m p t e d , andt h a t w i t h r a t h e r u n s a t i s f a c t o r y r e s u l t s• . . an d gave a t o t a l t h i c k n e s s o f 2100f e e t j u s t w e s t o f Z i o n Canyon and 20

m i l e s t o t h e e a s t o f L e e d s , U t a h .

Q u a t e r n a r y Alluv ium

S l i g h t l y c o n s o l i d a t e d and u n c o n s o l i d a t e da l l u v i u m o c c u p i e s o n l y a s m a l l p o r t i o n o f t h eS i l v e r Reef d i s t r i c t b u t i s most p r o minen t i n th en o r t h e r n and s o u t h w e s t e r n p a r t s and a l o n g t h eVi rg i n R i v e r. P a r t of t h e a l l u v i a l cove r r ema ins

as f l a t - t o p p e d e r o s i o n remnants and t e r r a c e s belowth e high r i d g e s of J u r a s s i c r o c k s , and y e t l o c a l l yl i e s more t h a n 100 f e e t above t h e b e d s o f t h ep r e s e n t s t r e ams . The o t h e r p a r t cove r s th e bo t tomsof th e v a l l e y s and i t s s u r f a c e i s only a few f e e ta b o v e t h e s t r e a m s and d r y w a s h e s i n t h e a r e a .

B o u l d e r Alluv ium

The m a t e r i a l o c c u p y i n g t h e t e r r a c e s ande r o s i o n remnan t s i s d e s i g n a t e d t h e B o u l d e r A l l u vium i n view of th e l a rg e bou lde r s of l a t i t e (Gardner,p . 243 , 1 9 4 1 ) , l i m e s t o n e , q u a r t z i t e c o n g l o m e r a t e ,an d b row n s a n d s t o n e i t c o n t a i n s a l o n g ~ i t h ani n t e r s t i t i a l f i l l i n g of sand and- s i l t . Remnantso f t h i s m a t e r i a l a r e as much as 50 f e e t t h i c k .

B e s t e x p o s u r e s o f t h e B o u l d e r Al luv ium a r e

a t t h e o ld town o f S i l v e r R e e f and wes t be tweent h e Whi te R ee f and t h e Nava jo s a n d s t o n e l e d g e s .The a l luv ium a l s o o c c u r s e a s t of S i l v e r Reef andi n t h e town of L e e d s , and t o t h e e a s t and s o u t hwhere i t c o v e r s p a r t o f t h e Shinarump f o r m a t i o n .To th e w e s t , s o u t h of th e C a l i f o r n i a . mine , a s u bsequen t v a l l e y i s f i l l e d wi t h th e Boulder Alluvium.O u t l i e r s o c c u r n o r t h o f t h e j u n c t i o n o f U. S .Highway 91 and S t a t e Highway 1 7 , c e n t e r i n g n e a r

t h e mouth o f a l a r g e canyon i n t h e Nava jo s a n ds t o n e s . South o f H a r r i s b u r g , i n P u rg a t o r y B a s i n ,s i m i l a r d e p o s i t s c r o p o u t , and t e r r a c e r e m n a n t smore t h a n 40 f e e t above t h e p r e s e n t s t r e a m l e v e la r e c l e a r l y v i s i b l e .

- 39 -



D i r e c t l y n o r t h o f Leeds on P a u l m a r H i l l ane r o s i o n a l r e m n a n t more t h a n 30 f e e t t h i c k o c c u r sas a c a p p i n g 100 f e e t a b o v e , and c o m p l e t e l y i s ol a t e d f r o m , o t h e r a r e a s o f a l l u v i a l c o v e r . Sim-i l a r r emnan t s a r e n e a r H a r r i s b u rg and t o t he sou thwhere s e v e r a l h i l l s a r e capped by th e Boulde r A l-l u v i u m . P o s s i b l y 60 p e r c e n t o f t h e B o u l d e r A l l u -vium has been eroded away.

Lower l e v e l t e r r a c e d e p o s i t s o f B o u l d e r A l-luv ium c o v e r much of t h e Upper T r i a s s i c sed imen t ss o u t h w e s t o f Leeds . These d e p o s i t s a re c o - e x t e ns i v e w i t h t h e a l l u v i u m p r e s e n t i n P u rg a t o r y B a s i nand t h a t e a s t and s o u t h o f L e e d s . E r o s i o n h asa l s o g r e a t l y m o d i f i e d t h e s e l o w e r l e v e l d e p o s i t s .

The d i s t r i b u t i o n , t h e 20 f o o t or more d i a m e t e ro f some o f t h e i n c l u d e d b o u l d e r s , and t h e l o c at i o n o f t h e d e p o s i t s g i v e s some i d e a as t o t h eo r i g i n and age o f t h e B o u l d e r Al luv ium. The f a c t

t h a t t h e g r e a t e s t amount o f a l l u v i u m i s n e a r th emouth o f l a r g e canyons which c u t r o c k s o f s i m i l a rc o m p o s i t i o n t o t h e i n c l u d e d b o u l d e r s s u g g e s t s a

s o u r c e i n t h a t d i r e c t i o n . The c o m p l e t e l a c k o fb e d d i n g i n some p l a c e s , and rough form of s t r a t if i c a t i o n i n o t h e r l o c a l i t i e s , s u g g e s t s t h a t s t reama c t i o n and p o s s i b l y a n o t h e r agen t were r e s p o n s i b l ef o r t h e d e p o s i t s .

The m a j o r d e p o s i t s were p r o b a b l y t h e r e s u l to f d e p o s i t i o n by s t r e a m s on l a r g e a l l u v i a l f a n st h a t s p r e a d and p o s s i b l y c o a l e s c e d a long th e f o o to f t h e h i g h c l i f f s . At t i m e s , however, mudflowsmay h a v e s w e p t down t h e n a r r o w c a n y o n s i n t h er e s i s t a n t Navajo s a n d s t o n e and s p r e a d l a t e r a l l yo v e r l a r g e a r e a s i n f r o n t o f t h e c a n y o n s . Landf o r m s o f s u c h d e p o s i t s c a n n o t now be i d e n t i f i e db e c a u s e o f t h e e x t e n s i v e e r o s i o n , b u t t h e l a c k

o f b e d d i n g and b o u l d e r s i z e s u g g e s t s s u c h ano r i g i n f o r a t l e a s t p a r t o f t h e d e p o s i t s .

Not a l l o f t h e a l l u v i u m was d e p o s i t e d a t th esame t i m e , as o u t l i e r s of t h e h i g h e r l e v e l BoulderA l l u v i u m s u g g e s t s a p e r i o d o f a t l e a s t 100 f e e t



o f e r o s i o n b e f o r e l o w e r t e r r a c e m a t e r i a l was d e -p o s i t e d . Even t h i s l a t e r v a l l e y f i l l i n g has beenm o d i f i e d by e r o s i o n . E a s t o f L e e d s , v a l l e y s 60f e e t o r more i n d e p t h have been c u t t h r o u g h t h e

l o w e r l e v e l d e p o s i t s an d i n t o t h e u n d e r l y i n gs h a l e s . Thus a minimum o f 160 f e e t and as mucha s 340 f e e t of s e d i m e n t h a s b e e n r emoved s i n c et h e d e p o s i t i o n of t h e Paulmar H i l l u p p e r t e r r a c eB o u l d e r A l luv ium .

The e x t e n t of e r o s i o n and t h e t ime r e q u i r e dt o accompl i sh i t and a l s o t h e need f o r a g r e a t e rabundance o f w a t e r t h a n u n d e r t h e p r e s e n t a r i d

c l i m a t e s u g g e s t s t h a t d e p o s i t i o n of th e a l luv iumt o o k p l a c e some t i m e i n t h e Wi s c o n s i n s t a g e o ft h e P l e i s t o c e n e e p o c h .

R e c e n t A l l u v i u m

F l a t - t o p p e d e r o s i o n r e m n a n t s above t h e i nt r i c a t e l y w e a t h e r e d C h i n l e s h a l e s a r e composedo f sand and s i l t wi th some minor s m a l l b o u l d e r s

o f l a t i t e , q u a r t z i t e c o n g l o m e r a t ~s a n d s t o n e andl i m e s t o n e . At a l o w e r l e v e l , sand and b o u l d e r soccupy t h e s t r eam b e d s . Thi s i s e s p e c i a l l y t r u ea long t h e Vi rg i n R i v e r. E a s t o f Leeds and n o r t ho f t h e Va n d e r b i l t m i n e more t h a n a s q u a r e m i l eo f wind b low n sand c o v e r s e r o d e d C h i n l e rocks .

The Qua te rna ry a l luv ium was d e p o s i t e d d u r i n ga t l e a s t two p e r i o d s of t i m e . West o f H a r r i s b u rgd e p o s i t i o n of sands f o l l o w e d t h e e r o s i o n o f mucho f t h e B o u l d e r A l l u v i u m and t e n d e d t o f i l l t h ev a l l e y s which had been c u t . L a t e r , e r o s i o n sweptaway p a r t o f · t h i s and r e d e p o s i t e d much o f i t i nt h e s t r e a m v a l l e y s . E r o s i o n r e m n a n t s were l e f tb e h i n d as c a p p i n g s on t h e C h i n l e s h a l e s .

On t h e E a s t Ree f wind h as d e p o s i t e d a fewf e e t o f sand o v e r low o u t c r o p s of th e Chin l e f o rm a t i o n . T h i s d e p o s i t i o n i s s t i l l go ing on. Thes o u r c e o f t h e m a t e r i a l i s t h e p r o m i n e n t N a v a j os a n d s t o n e and C h i n l e s a n d s t o n e s s u r r o u n d i n g t h ea r e a .

- 41 -



IGNEOUS ROCKS

I g n e o u s r o c k s a re a b s e n t i n t h e main min inga r e a and e x c e p t f o r a s m a l l v o l c a n i c c o n e ande r o d e d b a s a l t f l ow n e a r t h e D u f f i n Mine , a l l o ft h e r o c k s occu r s o u t h and e a s t of th e Vi rg i n Rive r.

B a s a l t Flows

A s m a l l v o l c a n i c cone composed o f s c o r i a c e o u s

b a s a l t occurs a few hundred f e e t n o r t h of th e Duff inM i n e . J u s t t o t h e s o u t h o f t h e mine an e r o s i o nr e m n a n t o f a f low o f s i m i l a r c o m p o s i t i o n c r o p so u t sou thward a lmos t t o t h e r i v e r . South and e a s to f t h e Vi r g i n R i v e r an e x t e n s i v e a r e a i s c o v e r e db y b a s a l t i c f l o w s . Along t h e s o u t h e a s t m a rg i no f t h e a r e a s e v e r a l s m a l l v o l c a n i c c o n e s r i s ea b o v e t h e l a v a f l o w s .

The v o l c a n i c r o c k n e a r t h e D u f f i n Mine i sa d e n s e somewha t v e s i c u l a r b a s a l t . L o c a l l y , a

p y r o c l a s t i c c o m p o s e d o f f r a g m e n t s o f f e l d s p a rand d e n s e b a s a l t i c m a t e r i a l o c c u r s a t i t s b a s e .The v o l c a n i c r o c k l i e s on t h e e r o d e d e d g e s o ft h e Chin le f o r m a t i o n and c o v e r s p a r t of t h e S i l v e rR e e f s a n d s t o n e n o r t h o f t h e m i n e . S o u t h o f t h er i v e r , e x c e p t f o r s m a l l windows , t h e f l o w s c o v e r

a l l o f t h e C h i n l e and t h e Navajo s a n d s t o n e .

Though t h e v o l c a n i c c o n e n e a r t h e D u f f i nMine i s o n l y s l i g h t l y e r o d e d , a s t r e a m c h a n n e lh a s b e e n c u t ~ h r o u g hmore t h a n s i x f e e t o f a r e -

l a t e d f low o f b a s a l t and 20 f e e t i n t o t h e u n d e rl y i n g s h a l e s and s a n d s t o n e . To t h e s o u t h th eVi r g i n R i v e r h as c u t a c h a n n e l t h r o u g h t h e b a s a l tf l o w s o v e r a d i s t a n c e o f t h r e e m i l e s a l o n g t h e

e d g e o f t h e S h i n a r u m p h o g b a c k .

A p p a r e n t l y l a v a o f b a s a l t i c c o m p o s i t i o nw e l l e d o u t f rom t h e d i f f e r e n t cones on to a t o p o gr a p h y n o t v e r y d i f f e r e n t f rom t h a t o f t h e p r e se n t . I n g e n e r a l t h e l a v a f l o w s f o l l o w e d s o u t hw e s t d r a i n a g e l i n e s . The f low s o u t h o f t h e Vi r -



g i n R i v e r was s t o p p e d i n i t s wes tward movementby t h e Shinarump f o r m a t i o n hogback and t u r n e d t ot h e south f o r seve ra l mi l e s . Gardner (p . 244, 1941)d a t e s c o r r e s p o n d i n g b a s a l t s j u s t t o t h e e a s t o fth e a rea as Qua te rna ry. There a re n o t s u f f i c i e n tf i e l d d a t a i n t h e S i l v e r Reef d i s t r i c t t o a l l o wa c l o s e r d a t i n g , though t h e y can be s a i d t o havepreceded th e d e p o s i t i o n of some of th e lower l e v e lB o u l d e r A l l u v i u m f o r a c a p p i n g of i t o c c u r s onan e r o s i o n remnan t of b a s a l t s o u t h of th e Duff inMine.

- 43 -

II

I



STRUCTURAL SETTING OF THE DISTRICT

The H a r r i s b u rg ( S i l v e r Reef ) mining d i s t r i c ti s un ique i n i t s s t r u c t u r a l s e t t i n g . To th e e a s tt h e ~ e l l - k n o ~ nH u r r i c a n e f a u l t ( G a r d n e r, pp . 241-260 , 1941) ~ i t h s t r a t i g r a p h i c d i s p l a c e m e n t s r a n gi n g t o a s much as 1 0 , 0 0 0 f e e t , s e p a r a t e s t h eb l o c k c o n t a i n i n g t h e d i s t r i c t f rom t h e C o l o r a d oP l a t e a u p r o p e r . Westward i s th e B a s i n and Rangep r o v i n c e whose e a s t e r n b o u n d a r y i n t h i s v i c i n i t y

i s t aken as th e BeaverDam

Mountains and t he d ra inaged i v i d e n o r t h o f t h e P i n e Va l l e y M o u n t a i n s ( C a l -l a g h a n , 1 9 4 6 ) . S t r u c t u r a l l y , th e a r e a i s t r a n s i -t i o n a l between two major p r o v i n c e s . I n i t s deg reeo f f o l d i n g and m i n o r t h r u s t f a u l t i n g t h e a r e a i smore c l o s e l y r e l a t e d t o t h e B a s i n and Range t h a nt o t h e P l a t e a u p r o v i n c e .

F o l d s

Broad open f o l d s c o n s t i t u t e th e main s t r u c t u r a lf e a t u r e s i n t h e Leeds a r e a . The mos t p r o m i n e n tf o l d , t h e Vi rg i n a n t i c l i n e , may be t r a c e d f o r moret h a n 18 m i l e s sou thwes tward . S u b s i d i a r y f o l d s t ot h e w e s t o f t h e m a j o r f o l d a l s o o c c u r , b u t b o t ht h r u s t f a u l t i n g and normal f a u l t i n g have modi f i edt h e s u r f a c e e x p r e s s i o n of t h e s e f o l d s .

Vi rg i n A n t i c l i n e

The Vi r g i n a n t i c l i n e i s a c o n t i n u a t i o n o ft h e s t r u c t u r e n o t e d by Gardner (p . 250 , 1941) andmapped by Dobbin (p . 136 , 1 9 3 9 ) . Thi s symmet r i ca lf o l d t r ends approximate ly N. 30 0 -40 0 E. f o r a t o t a ld i s t a n c e o f a t l e a s t 18 m i l e s f rom a p o i n t s o u t ho f S t . George , Utah , t o n o r t h e a s t of Leeds , wherei t p l u n g e s n o r t h w a r d u n d e r a c o v e r o f Q u a t e r n a r ya l l u v i u m and b a s a l t sou th and wes t o f To q u e r v i l l e .The l i m b s d i p f rom 1 8 - 3 6 d e g r e e s . T h r e e domeswere d e s c r i b e d by Dobbin ( p p . 140-144 , 1 9 3 4 ) , th eH a r r i s b u r g , Wa s h i n g t o n , and Blooming ton . S i l v e rR e e f i s j u s t n o r t h of t h e H a r r i s b u r g Dome, t h en o r t h e r n m o s t o f t h e t h r e e .

44



The h i g h l y r e s i s t a n t Shinarump c o n g l o m e r a t efo rms a hogback r i d g e a round a c o r e o f Moenkopif o r m a t i o n and c o m p l e t e l y s u r r o u n d s t h e f o l d ont h e n o r t h . Near t h e o ld town o f H a r r i s b u r g t h ew e s t l imb o f t h e f o l d t r e n d s N.30 0 E. and d i p s

200

-300

W. To th e wes t t h e d ip g r a d u a l l y f l a t t e n st o 18 d e g r e e s . The beds on t h e e a s t l imb n o r t hof th e Duff in Mine d ip 16 0 E. Loca l drag on f a u l t smay s t e e p e n t h e e a s t d i p c o n s i d e r a b l y , howeve r.From t h e D u f f i n Mine s o u t h w a r d t o t h e Vi r g i nR i v e r , where t h e b e d s o v e r l y i n g Sh ina rump c o ng lomera t e d i s a p p e a r b e n e a t h t h e R i v e r g r a v e l s andQua te rna ry b a s a l t , t h e beds have a f a i r l y c o n s t a n ts t r i k e of N.40 0 E. and d ip of 28 0 E.

Near t h e To q u e r v i l l e and Va n d e r b i l t m i n e s ,j u s t n o r t h o f t h e D u f f i n m i n e , t h e S i l v e r R e e fs a n d s t o n e t r e n d s n o r t h and d i p s 1 7 0 E. N o r t hward th e e a s t l imb of t h e Vi rg i n a n t i c l i n e f l a tt e n s and t h e s t r i k e changes s h a r p l y t o e a s t - w e s t .Here th e beds form t h e n o r t h p l u n g i n g nose of t h ef o l d . Wi t h i n P u r g a t o r y B a s i n t h e b e d s d i p c o nt i n u o u s l y n o r t h f rom t h e H a r r i s b u r g r o a d n o r t h

w a r d . L o n g i t u d i n a l f a u l t s somewhat modi fy t h eb e d s o f t h e f o l d above t h e S h i n a r u m p b u t h a v el i t t l e a p p a r e n t e f f e c t on t h e Shinarump o u t c r o p s .The wes t l imb of t h e Vi rg i n a n t i c l i n e , s o u t h andw e s t o f L e e d s , h a s b e e n somewha t m o d i f i e d byf a u l t i n g and p a r t l y c o v e r e d by a l l u v i u m .

S u b s i d i a r y f l e x u r e s o c c u r on t h e n o r t h w e s tf l a n k o f t h e Vi r g i n a n t i c l i n e . The a x i s o f an

open s y n c l i n e t r e n d s N.300

E. t o n o r t h and l i e sj u s t w e s t o f L e e d s . A few h u n d r e d f e e t f u r t h e rw e s t , a p a r a l l e l t r e n d i n g a n t i c l i n e p l u n g e s t ot h e n o r t h . Both f o l d s g r a d u a l l y c o a l e s c e s o u t hward w i t h t h e l a r g e r Vi rg i n a n t i c l i n e .

Leeds A n t i c l i n e

The Leeds a n t i c l i n e i s wel l exposed on Tecumseh

H i l l j u s t s o u t h o f t h e o ld town o f S i l v e r R e e f( s e e P l a t e I ) . E r o s i o n h as e t c h e d o u t t h e morer e s i s t a n t S i l v e r Reef s a n d s t o n e and t h e f o l d i se x p r e s s e d t o p o g r a p h i c a l l y . Here t h e a x i s t r e n d s

- 45 -



n o r t h and t h e f o l d p l u n g e s a p p r o x i m a t e l y 15d e g r e e s t o t h e n o r t h u n d e r t h e B o u l d e r Al luv iumn e a r t h e Tecumseh m i n e . The w e s t Buckeye R e e fforms th e west l imb of th e f o l d and t r e n d s approx-i m a t e l y No. 34 0 E . , 20 0 W. L o c a l v a r i a t i o n s o fs t r i k e and d ip o c c u r n e a r th e Savage , K i n n e r, andC a l i f o r n i a s h a f t s where t h e d i p i n c r e a s e s t o 45d e g r e e s i n a d i s t a n c e o f 100 f e e t o r l e s s . Thef l e x u r e i s nea r th e c o n t a c t of th e Boulder Alluviumand th e S i l v e r Reef s a n d s t o n e . Down d ip th e bedsf l a t t e n and i t i s r e p o r t e d (Newman, E. W., p e r s o n a lcommunicat ion) t h a t i n th e A.S.& R. s h a f t th e bedsd ip g e n t l y t o t h e e a s t .

The Whi te R e e f w e s t o f t h e Buckeye R e e f ,s t r i k e s N.30 0 W. f rom t h e S o u t h Thompson minea r e a t o n o r t h o f t h e Barbee and Walker mine wheret h e r e e f d i s a p p e a r s b e n e a t h t h e a l l u v i u m . L o c a lv a r i a t i o n s a r e o f l i t t l e or no c o n s e q u e n c e . An

e x c e p t i o n o c c u r s 600 f e e t s o u t h o f th e Leeds No.2 s h a f t where th e d i p changes from 35 0 t o 17 0 W.

The s t r u c t u r e i s c o m p l e t e l y anomalous t o t h a t of

s u r r o u n d i n g a r e a s and may r e p r e s e n t pr imary depos-i t i o n a l slump.

From t h e Thompson mine t o t h e s o u t h e r n endo f th e Leeds a n t i c l i n e h a l f a mile n o r t h of H a r r i sb u r g t h e t r e n d o f t h e Whi te R e e f i s c o n s t a n t .The a x i a l t r e n d o f t h e a n t i c l i n e v a r i e s f rom N.28 0 E. t o N.40 0 E. South of H a r r i s b u rg th e WhiteReef r e p r e s e n t s p a r t of th e west l imb of th e Virg in

a n t i c l i n e .

Drag on a n o r t h - t r e n d i n g f a u l t h as s t eepenedt h e e a s t l imb of th e Leeds a n t i c l i n e , and i n f a c t ,may w e l l have formed a p a r t o f th e f o l d by d r a gg i n g t h e b e d s down t o t h e e a s t . On TecumsehH i l l th e beds s t r i k e N.200 W. and d ip from 20 0 t o45 E. S o u t h o f t h e Leeds Cemetery t h e s t r i k e sand d i p s a r e v a r i a b l e on t h e e a s t l i m b . Theyr a n g e f rom N.30 E. t o N. 40 E. and d i p as mucha s 15 0 E. About a h a l f m i l e n o r t h of H a r r i s b u rgt h e d i p i s g e n t l y t o t h e s o u t h . In a few s c o r e so f f e e t i t r e v e r s e s i n d i r e c t i o n and t h e S h i n a -rump c o n g l o m e r a t e becomes t h e t r u e w e s t l imb o ft h e Vi r g i n a n t i c l i n e .

46



Leeds S y n c l i n e

The Leeds s y n c l i n e fo rms t h e s o u t h e r n p a r tof th e Leeds Va l l e y. Here , i n f o l d e d Chin le s h a l e sand s a n d s t o n e s have w e a t h e r e d t o t h e r i c h s a n d y

loam of t h e v a l l e y f l o o r . The f o l d b e g i n s a b o u ta m i l e s o u t h of Leeds and p l u n g e s n o r t h Ya r d from5 ° - 2 1 ° . The a x i a l t r e n d r a n g e s from N. 30 0 E. t oN. 5 ° W. The l i m b s o f t h e f o l d c o n s t i t u t e t h ew e s t l i m b o f t h e Vi r g i n a n t i c l i n e and t h e e a s tl imb of th e Leeds a n t i c l i n e r e s p e c t i v e l y . The f o l di s open and i s a s much as 5000 f e e t i n w i d t h .

The s o u t h e r n p a r t o f t h e B u t t e R e e f w e s to f Leeds r e p r e s e n t s an e r o s i o n a l r e m n a n t o f t h eS i l v e r Ree f s a n d s t o n e a l o n g t h e a x i s of t h e s y nc l i n e . N o r t h o f t h e r o a d c r o s s i n g t h e B u t t eR e e f , t h e a x i s i s o f f s e t a few t e n s o f f e e t t oth e wes t by a n o r t h e a s t t r e n d i n g f a u l t . The Leedss y n c l i n e c o n t i n u e s th rough t h e Buckeye Reef n o r t hw a r d , b u t f a u l t i n g h a s so d i s t u r b e d t h e b e d s onb o t h t h e e a s t and w e s t l i m b s t h a t t h e o r i g i n a lf l e x u r e i s n o t r e a d i l y a p p a r e n t . Nor th o f t h e

r e e f t h e f o l d p l u n g e s f rom 5 0 -1 6 0 n o r t h w a r d b en e a t h t h e Q u a t e r n a r y a l l u v i u m .

J o i n t s

A d i s t i n c t i v e p a t t e r n o f s t r i k e , o b l i q u e , andd ip j o i n t s o c c u r s i n th e Leeds and Tecumseh s a n ds t o n e s , b u t j o i n t p a t t e r n s i n o t h e r b e d s i n th ea r e a , wi th th e e x c e p t i o n o f th e Shinarump c o n g l omerate and th e mass ive Navajo sands tone , a re absen to r i n d i s t i n c t . In view of t h e p o s s i b i l i t y t h a tsome of t h e ore b o d i e s i n th e s a n d s t o n e might havebeen l o c a l i z e d by t h e s e s t r u c t u r e s , s e v e r a l hundredb e a r i n g s were t a k e n on t h e d i f f e r e n t s e t s . Thes tudy i n d i c a t e d t h a t th e dominan t s e t s t r e n d a fe ydegrees e a s t and wes t of n o r t h , whereas th e s t r i k eo f t h e l e s s numerous s e t s a p p r o a c h e s e a s t - w e s t .The d i p i s n e a r l y v e r t i c a l , b u t c h a n g e s wi th t h ed i f f e r e n t s e t s . Genera l l y, t he most numerous j o i n t sa re th e l o n g e s t ; some of th e i n d i v i d u a l ones ex tendas much as 300 o r 400 f e e t a long t h e s t r i k e . Thea v e r a g e l e n g t h , h o w e v e r , i s o n l y a f e y t e n s o f

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f e e t . The b e s t e x p o s u r e s a r e on th e Whi te R e e f ,B u t t e R e e f , and Buckeye R e e f ; t h o s e on t h e E a s tR e e f a r e o n l y p o o r l y d e v e l o p e d .

White Reef

A d i s t i n c t i v e j o i n t p a t t e r n i s w e l l exposedi n th e Tecumseh sands tone i n th e Thompson-Cobb minesa r e a . The s e t s t r e n d i n g and d i p p i n g N.500 E . , 70° -8 0 ° E' b N. 1 0 ° - 2 3 ° W., 6 0 ° - 7 0 ° NE., and N. 5° E . ,70° -80 E. a r e t h e most p r o m i n e n t . A l e s s p r o m in e n t s e t t r e n d s N.85° E . , and d i p s 80° S. t o v e r t ic a l . By i n t e r s e c t i n g th e o t h e r s i t c u t s th e s a n ds t o n e i n t o b l o c k s . O t h e r l e s s p r o m i n e n t j o i n t sv a r y f rom t h e s e t r e n d s . To t h e n o r t h on th e WhiteR e e f , j u s t w e s t o f t h e A.S.& R. s h a f t a s e t t r e n di n g N. 5 ° - 1 5 ° E. and d i p p i n g 6 0 ° - 8 0 ° E. i s w e l lshown. I t i s i n t e r s e c t e d , b u t n o t c u t , by a s e tt r e n d i n g N. 80° E. t o e a s t - w e s t and d ipp ing 70° - 85°

S. w h i c h b r e a k s t h e L e e d s s a n d s t o n e i n t o l a r g er e c t a n g u l a r b l o c k s . The o t h e r p r o m i n e n t s e t s e xposed t o t h e sou th do n o t occur i n th e l a t t e r a r ea .

The N . 5 0 - l 5 ° E. s e t con t inues t o th e n o r t h where a N.10° -150 w., 70° -75° NE. s e t becomes prominen t . Nearth e Barbee and Walker mine two ob l ique f a u l t s cut ther e e f and a n o t h e r j o i n t s e t t r e n d i n g N. 300 W. andd i p p i n g 7 0 ° - 7 5 ° NE. p a r a l l e l s t h e b r e a k s .

Buckeye Reef

J o i n t s a r e n o t numerous s o u t h of t h e Savage

s h a f t on th e Buckeye R e e f , nor do th e few exposu resobse rved show as c h a r a c t e r i s t i c a p a t t e r n as t h o s eon the White Reef . The most prominent s e t s , however,t r e n d N.50-100 W. and d ip v e r t i c a l l y , and N.200-3 0 ° E. and d i p 7 0 ° - 7 5 ° E. A l e s s d i s t i n c t i v e s e tt r e n d s N.75° W. t o e a s t - w e s t and th e d ip r anges from75° S. t o 75° N.

J o i n t s a r e much b e t t e r e x p o s e d on TecumsehH i l l i n t h e Tecumseh s a n d s t o n e . The main s e t ont h e w e s t l i m b o f t h e a n t i c l i n e r a n g e s i n t r e n df r o m N. t o N . 5 ° E. and d i p s 60° E. t o 9 0 ° . Ont h e e a s t s i d e o f t h e a n t i c l i n e , t h e j o i n t s d i ps t e e p l y on t h e w e s t . Two o t h e r s e t s , one t r e n di n g N o r t h , 7 0 ° - 8 0 ° N ., and t h e o t h e r N.700 W. t o

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E a s t and d i p p i n g t o 90 0 c u t , b u t do n o t d i s p l a c e ,t h e n o r t h t r e n d i n g j o i n t s above . L o c a l l y , a s h e a r " 'p a t t e r n i s supe r imposed on t h e j o i n t sys t em.

B u t t e Ree f

S e v e r a l j o i n t s e t s a r e e x c e p t i o n a l l y w e l lshown on t h e B u t t e R e e f . The dominan t t r e n d s a reN . 4 5 ° W. w i t h d i p s o f 75 0 S . t o 90 0 and N.JO o -40 0 W. w i t h n e a r v e r t i c a l d i p s . These j o i n t s c u tb o t h th e Leeds and Tecumseh s a n d s t o n e s and show nochange i n s t r i k e or d ip when t hey c r o s s th e c o n t a c t .A s i m i l a r p a t t e r n i s exposed i n th e Leeds H i l l s e c -t i o n a s h o r t d i s t a n c e n o r t h .

E a s t Reef

Few j o i n t s are exposed on th e Eas t Reef . Gent les l o p e s may have ac t ed as a p r o t e c t i o n a g a i n s t s c o u rand e t c h i n g ou t of th e j o i n t s by r a i n w a t e r . On t h enose of th e Vi r g i n a n t i c l i n e a few p o o r l y exposedj o i n t s t r e n d N.lO o E . , d i p p i n g 65 0 E. and N.70 0 W.

d i p p i n g 90 0 • Near t h e Va n d e r b i l t mine two s e t s ,one t r end ing N. 6° W. and dipp ing BOO W. and th e o t h e rt r e n d i n g N.B5 E . , and d i p p i n g 90 0 o c c u r i n t h eD u ff i n and Tecumseh s a n d s t o n e s . J u s t s o u t h of th eDuff in mine two s e t s t r e n d N.lO o W., d i p p i n g BOO W.,and N.BOo W. d ipp ing 56 0 W.

Or ig in

S e v e r a l f a c t s a r e i m p o r t a n t i n c o n s i d e r i n gt h e o r i g i n o f t h e j o i n t s :

a . A s m a l l t h r u s t f a u l t and a d j a c e n t s h e a r sn e a r t h e Gad s h a f t on t h e Buckeye Reef a r e l a t e rt h a n t h e j o i n t s and d e s t r o y o r mask them on t h ef o o t w a l l Of t h e f a u l t . The t h r u s t and s h e a r i n ge x p l a i n s t h e s c a r c i t y o f j o i n t s i n t h i s p a r t o ft h e Buckeye R e e f .

b . S m a l l n o r m a l f a u l t s c u t t i n g t h e Whi teReef n e a r t h e Barbee and Walker mine do n o t c o r -r e s p o n d i n d i r e c t i o n wi th t h e j o i n t t r e n d s t hougha s e t o f f r a c t u r e s p a r a l l e l t h e f a u l t s . Thoughe x p o s u r e s a re n o t t h e b e s t , t h e f a u l t and accom-p a n y i n g f r a c t u r e s a p p e a r t o c u t t h e j o i n t s y s t e m .

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c . The t r e n d s of th e j o i n t s on th e t h r e e r e e f sa r e d i f f e r e n t . F o r e x a m p l e , t h o s e on t h e B u t t eReef va ry c o n s i d e r a b l y from t h o s e on Tecumseh H i l l ,a s do a l s o t h e s t r u c t u r e s , a s y n c l i n a l t r o u g hv e r s u s an a n t i c l i n a l c r e s t .

d . R e s t o r a t i o n of th e sands tone t o a h o r i z o n -t a l s u r f a c e f a i l s t o y i e l d a s i m i l a r p a t t e r n f o rt h e s e t s on t h e d i f f e r e n t r e e f s .

S u m m a r i z i n g , t h e j o i n t s p r e c e d e b o t h t h et h r u s t and norma l f a u l t s , y e t t h e p a t t e r n on t h ei n d i v i d u a l r e e f s do n o t match when t h e b e d s a r e" r e s t o r e d " t o a h o r i z o n t a l p o s i t i o n . They a r et h u s r e s t r i c t e d i n t i m e f rom t h e p e r i o d a f t e rt h e b e d s w e r e r a i s e d f rom a n e a r l y h o r i z o n t a lp o s i t i o n t o a t i m e b e f o r e t h e n o r m a l and t h r u s tf a u l t i n g o c c u r r e d . The change i n p a t t e r n c o r r e s -ponding wi th a change i n s t r u c t u r e on th e d i f f e r e n tr e e f s s u g g e s t s t h a t t h e j o i n t s were formed a t t h e

t i m e o f t h e f o l d i n g of th e r o c k s , and a r e t h e r e -s u l t o f th e same d e f o r m a t i o n a l s t r e s s e s .

F a u l t s

Though f a u l t s a r e n o t abundan t i n t h e S i l v e rReef d i s t r i c t , t h e few t h a t do o c c u r a re of impor-t a n c e b o t h s t r u c t u r a l l y and e c o n o m i c a l l y. Normalf a u l t s w i t h s t r a t i g r a p h i c d i s p l a c e m e n t s r a n g i n g

t o more t h a n JOO f e e t a r e l o c a l i z e d on t h e n o r t hp l u n g i n g noses of t h e f o l d s . G e n e r a l l y th e f a u l t sp a r a l l e l t h e t r e n d s o f t h e axes o f t h e f o l d s b u tl o c a l l y t h e y may t r a n s e c t t hem. The f a u l t s a rea l m o s t w h o l l y r e s t r i c t e d t o t h e C h i n l e f o r m a t i o nand a re e s p e c i a l l y d i s t i n c t i v e where t h e y c u t th er e s i s t a n t S i l v e r R e e f s a n d s t o n e member. Draga long th e f a u l t s i s n o t common, though l o c a l l y th eb e d s have b e e n d r a g g e d f rom h o r i z o n t a l t o a l m o s tv e r t i c a l . Some o f t h e f a u l t s show l i t t l e d i s -p l a c e m e n t b u t a wide s h e a r z o n e , w h e r e a s o t h e r sw i t h a r e l a t i v e l y l a r g e d i s p l a c e m e n t show l i t t l e

o r no s h e a r i n g e x c e p t on t h e f a u l t i t s e l f . Mosto f th e f a u l t s a r e o f t h e p i v o t a l t y p e so t h a t t h eamount o f d i s p l a c e m e n t v a r i e s a l o n g t h e s t r i k e .

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On th e nOBe o f t h e Vi rg i n a n t i c l i n e t h e majorf a u l t s c u t t h e S i l v e r Reef s a n d s t o n e i n t o l a r g e ,v a r i o u s l y t i l t e d b l o c k s . West of Highway 91 th eS i l v e r Reef s a n d s t o n e i s d i s p l a c e d s e v e r a l hundred

f e e t on a normal f a u l t . A few hundred f e e t f u rt h e r w e s t a n o t h e r p r o m i n e n t f a u l t t r e n d i n g n o r t hc u t s t h e e a s t l i m b o f t h e L e e d s a n t i c l i n e anddrops Duff in sands tone a g a i n s t Tecumseh s a n d s t o n e .O t h e r s m a l l e r l o n g i t u d i n a l f a u l t s o c c u r on t h en o s e o f t h e f o l d .

D i r e c t l y west o f th e o ld town of ~ i l v e rReeft h e White Reef s e c t i o n h as been o v e r t h r u s t t o th e

e a s t s e v e r a l hundred f e e t . The t h r u s t f a u l t d i p st o t h e w e s t and t r e n d s n o r t h - n o r t h e a s t , c l o s e l yf o l l o w i n g th e s t r i k e of th e bedding f o r a d i s t a n c eof s e v e r a l m i l e s .

Normal F a u l t s

F o r t h e s a k e o f c l a r i t y , t h e n o r m a l f a u l t si n t h e d i s t r i c t a r e d i s c u s s e d a c c o r d i n g t o t h e i rl o c a t i o n s on t h e White R e e f , B u t t e R e e f e t c .

Whi te Re e f

Smal l f a u l t s with s t r a t i g r a p h i c d i s p l a c e m e n t sof b u t a few i nches were observed on th e White Reefb u t t h e i r l i m i t e d e x t e n t d o e s n o t p e r m i t t h e i rb e i n g shown on t h e map. Only two no rma l o b l i q u ef a u l t s w i t h d i s p l a c e m e n t l a r g e enough t o r e c o r dwere n o t e d n e a r th e Barbee and Walker Mine a r e a .The sou the rnmos t of th e two shows an a p p a r e n t h o ri z o n t a l d i s p l a c e m e n t o f 25 f e e t measu red on t h es t r i k e of t h e f a u l t . The f a u l t c u t s a l l membersof t h e T r a i l H i l l s a n d s t o n e and d i s a p p e a r s u n d e ral luvium to th e e a s t . A s i m i l a r f a u l t 900 f e e t n o r t h

shows 40 f e e t a p p a r e n t h o r i z o n t a l d i s p l a c e m e n t .Both o f t h e f a u l t s t r e n d N.25° W., and d i p s t e e p l yt o th e s o u t h . N e i t h e r cou ld be t r a c e d any d i s t a n c ebecause of the a l l u v i a l c o v e r.

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Buckeye Reef

The Buckeye Reef i s c u t by a p r o m i n e n t s h e a rzone n e a r t h e C a l i f o r n i a Mine which i s r e l a t e d t o

n o r m a l f a u l t movement and w h i c h t r e n d s N.30 0 E.w i t h v e r t i c a l d i p . Though t h e s t r a t i g r a p h i c d i sp l a c e m e n t ~ i t h d o ~ n d r o pt o t h e ~ e s t c o u l d n o t bed e t e r m i n e d a c c u r a t e l y , C o l b a t h ( p e r s o n a l communic a t i o n ) on t h e b a s i s o f h i s u n d e rg r o u n d mapping ,s u g g e s t s a d i s p l a c e m e n t o f a few f e e t . Cumula t ivemovement t h r o u g h th e s h e a r zone may r e p r e s e n t muchmore d i s p l a c e m e n t , h o ~ e v e r .The zone a p p a r e n t l yg r a d e s i n t o a s h a r p f l e x u r e s o u t h ~ a r d ,b u t n o r t hw a r d i t i s a f a u l t w h i c h i s p a r t l y c o v e r e d bydumps and s a n d . A s i m i l a r s h e a r zone ends a g a i n s ta f a u l t d i p p i n g 30 0 -3 8 0 s o u t h - s o u t h e a s t 730 f e e tfrom th e Savage s h a f t . The s h e a r zone may r e p r e s e n tt h e d i s p l a c e d n o r t h e r n p o r t i o n o f t h e C a l i f o r n i af a u l t . The a s s o c i a t e d b r o k e n zone l o c a l l y i s asmuch as 80 f e e t i n w i d t h . To t h e n o r t h i t d i sa p p e a r s u n d e r dumps and sand c o v e r and j u s t e a s to f t h e Savage s h a f t may s p l i t and g r a d u a l l y d i eo u t .

Near t h e Tecumseh m i n e , t h r e e n o r t h - t r e n d i n gf a u l t s d i s p l a c e t h e b e d s as much as 30 f e e t i n ana p p a r e n t h o r i z o n t a l d i s p l a c e m e n t a l o n g t h e s t r i k eo f t h e f a u l t . The d i p s o f t h e f a u l t p l a n e s weren o t v i s i b l e , b u t v e r t i c a l s h e a r i n g o c c u r r e d p a r a ll e l t o them.

The m o s t p r o m i n e n t f a u l t s i n t h e mine a r e aa r e e a s t o f t h e c r e s t o f Tecumseh H i l l . Apparen th o r i z o n t a l d i s p l a c e m e n t a l o n g t h e f a u l t s i s asmuch as 130 f e e t . The T r a i l H i l l f a u l t w e s t o ft h e s m a l l c e m e t e r y b r i n g s D u f f i n s a n d s t o n e i nj u x t a p o s i t i o n ~ i t h Tecumseh s a n d s t o n e . In g e n e r a l ~

t h e f a u l t s ~ e s t o f t h e T r a i l H i l l f a u l t ( P l a t e I T )

drop b l o c k s d o ~ n t o t h e e a s t , whereas t o th e e a s t

o f i t t h e m i n o r f a u l t s d r o p b l o c k s t o t h e w e s t .S t r a t i g r a p h i c s e p a r a t i o n i s a p p r o x i m a t e l y 60 f e e t ,b u t i t may be much more t o t h e n o r t h and p r o g r e ss i v e l y l e s s t o t h e s o u t h . The amount of drag t h a to c c u r s may modify t h i s f i g u r e s o m e ~ h a t .Two s m a l le x p o s u r e s o f t h e f a u l t p l a n e i n d i c a t e t h a t t h ed ip r anges from 65 0 E. t o v e r t i c a l . The f a u l t shows



p r o g r e s s i v e i n c r e a s e i n d i s p l a c e m e n t down t o t h ee a s t t o w a r d t h e o ld town o f S i l v e r R e e f . S o u t ho f t h e S i l v e r R e e f c e m e t e r y w a s h , h o w e v e r , t h eu p t h r o w n b l o c k g r a d u a l l y becomes t h e downthrowns i d e f o r 500 f e e t and t h e n t h e f a u l t g r a d e s i n t oa s m a l l f l e x u r e and d i s a p p e a r s . The r e v e r s a l i nd i s p l a c e m e n t s u g g e s t s a s c i s s o r t y p e o f movementon t h e f a u l t w i t h p r a c t i c a l l y no d i s p l a c e m e n t a tt h e p i v o t a l p o i n t . E a s t o f t h e Tecumseh m i n e ,t h e f a u l t d i s a p p e a r s u n d e r t h e a l l u v i u m .

-- -- -- ----- ----------- ---

-- -:: . . . r _ _-- ----- - - - - - ---------- -

Figure 2 . Diagrammatic s e c t i o n along T r a i l H i l l f a u l t .

F i g u r e 2 . Dia g rammat i c s e c t i o n a l o n g T r a i lH i l l f a u l t .

- - - - - Represen t s datum l i n e i n f o o t wal l .- - - -- Repr e sen t s same datum l i n e i n h a n g -in g w a l l .

R e pre s e n t s o r i g i n a l p o s i t i o n of d atum l i n e .

- 53 -



A f a u l t 400 f e e t e a s t o f F i r e Clay H i l l d i -

v e rg e s sou thward from th e Tecumseh f a u l t and w i t h i na s h o r t d i s t a n c e a l m o s t p a r a l l e l s t h e main b r e a k .A s e r i e s of s p r i n g s , abundance o f v e g e t a t i o n , and

m i s s i n g s t r a t a i n d i c a t e i t s p r e s e n c e . The d i s -p l a c e m e n t i s n o t known, b u t s i n c e t h e movementi n v o l v e s only th e T r a i l H i l l s a n d s t o n e s and s h a l e st h e d i s p l a c e m e n t i s p r o b a b l y l e s s t h a n t h a t of th eT r a i l H i l l f a u l t . The f a u l t d i e s o u t w i t h i n 800f e e t t o t h e s o u t h .

Three o t h e r s m a l l normal f a u l t s d i v e r g e n o r t hf rom t h e e a s t w a l l o f t h e T r a i l H i l l f a u l t . Themovement a l o n g t h e s e f a u l t s has p roduced c r u s h i n gand minor b r e c c i a t i o n of t h e s a n d s t o n e . R e c e s s e shave formed a long t h e f a u l t zones where w e a t h e r i n ghas e t c h e d ou t t h e l e s s r e s i s t a n t r o c k . D i s p l a c em e n t s on t h e f a u l t s a r e o n l y a few f e e t and d e -c r e a s e n o r t h u n t i l t h e y a l s o d i e o u t i n a s h o r td i s t a n c e by g r a d i n g i n t o v e r y minor f l e x u r e s . Int h e v a l l e y 100-JOO f e e t e a s t of F i r e Clay H i l l twos m a l l n o r m a l f a u l t s d i s p l a c e a s a n d s t o n e l e d g eand d r o p t h e h a n g i n g w a l l t o t h e e a s t .

A h a l f m i l e t o t h e e a s t and n o r t h t h e B u t t eR e e f e x t e n s i o n i s l i m i t e d by one o f t h e l a r g e s tnorma l f a u l t s i n t h e S i l v e r Reef a r e a . The f a u l tc a n be t r a c e d a t l e a s t two m i l e s s o u t h f rom t h eL e e d s R e s e r v o i r . The s t r i k e r a n g e s f rom N . 2 5 -55°E. In a t r e n c h , dug f o r w a t e r a long t h e f a u l t

on t h e w e s t s i d e o f t h e B u t t e R e e f , s h e a r zonest r e n d N . J J o E . and d i p 70 o E. F r a c t u r e s b r e a k o f fa t an a c u t e a n g l e t o t h e s o u t h w e s t f rom t h e mainf a u l t 9 and a g r o u p o f s m a l l s p r i n g s r i s e a l o n gt h e m . N o r t h n e a r t h e L e e d s R e s e r v o i r p r o m i n e n td r a g c a u s e s some of t h e b e d s t o s t a n d v e r t i c a l l y ,whereas o t h e r s m a l l e r b locks i n t h e f a u l t zone haveb e e n r o t a t e d i n t o an o v e r t u r n e d p o s i t i o n . Trues t r a t i g r a p h i c d i s p l a c e m e n t on t h e f a u l t a p p r o x i -

m a t e s 380 f e e t .

Vi r g i n A n t i c l i n e Nose

Because o f t h e l a c k of min ing on t h e nose oft h e Vi r g i n a n t i c l i n e , l e s s d e t a i l i s l i s t e d f o rt h e f a u l t s i n t h i s a r e a . As shown on p l a t e I th e



S i l v e r Reef s a n d s t o n e b l o c k s have been r o t a t e d i nv a r i o u s d i r e c t i o n s . S t r a t i g r a p h i c d i s p l a c e m e n t sr a n g e f rom a few f e e t on some o f t h e b l o c k s t omore t h a n 150 f e e t . E a s t w a r d a c r o s s t h e nose o ft h e f o l d t h e f a u l t s t r e n d f rom a l m o s t n o r t h n e a r

t h e h ighway t o N.200

E. on t h e e a s t s i d e o f t h enose . To th e nor th t he f a u l t s a re covered by a l l u v -i u m , w h i l e t o t h e s o u t h some a l l u v i u m and t h eg r e a t s i m i l a r i t y of t h e r e d s h a l e s and s a n d s t o n e sbelow th e S i l v e r Reef sands tone make them e x t r e m e l yd i f f i c u l t t o t r a c e .

I n many r e s p e c t s t h e f a u l t s on t h e n o s e o fth e f o l d a re s i m i l a r t o o t h e r s d e s c r i b e d f o r f o l d

s t r u c t u r e s i n t h e Rocky Mounta in P r o v i n c e . I r w i n(p . 119-125 , 1926) summarizes and i n t e r p r e t s s t r u c -t u r a l d a t a on many o f t h e o i l p r o d u c i n g a n t i c l i n e si n t h i s p r o v i n c e . He c o n c l u d e s :

Now c e r t a i n l y , domes and a n t i c l i n e s a r el o c i o f maximum d i s t u r b a n c e d u r i n g t h e i rg r o w t h , and where t h e s t r a t a i n v o l v e da r e c o m p o s e d o f g r e a t t h i c k n e s s e s o f

s h a l e s , a l t e r n a t i n g wi th r e l a t i v e l y t h i nc o m p e t e n t mem b er s , t h e c o n d i t i o n s a r ei d e a l f o r a s h a k i n g - d o w n p r o c e s s whi chr e s u l t s i n g r a v i t y f a u l t i n g . • • •

. . . • t h e f a u l t s on u p f o l d s a r e , i n t h emain , l o c a l f e a t u r e s d e p e n d e n t upon t h ef o l d i n g f o r t h e i r o r i g i n , t h e n i t i sh i g h l y p r o b a b l e t h a t t h e f o l d i n g andf a u l t i n g a re e s s e n t i a l l y con temporaneous .

E a s t Reef

Underg round mapping a t t h e To q u e r v i l l e andVa n d e r b i l t m i n e s on t h e e a s t l i m b o f t h e Vi r g i na n t i c l i n e i n t h e S i l v e r Reef s a n d s t o n e member i n -d i c a t e s s e v e r a l f a u l t s . The f a u l t s have a f a i r l yc o n s t a n t s t r i k e o f N. 20 o -25 0 E. and d ip 65° -75 0 E.The h a n g i n g w a l l h a s b e e n d r o p p e d t o t h e e a s t .

The amount of d i sp l acemen t cou ld no t be de te rmined .Near t h e D u ff i n mine and t o t h e s o u t h f a u l t s a r en o t e v i d e n t . South and e a s t o f t h e Vi r g i n R i v e ra l l u v i u m and l a v a f l o w s a l m o s t c o m p l e t e l y c o v e rt h e s e d i m e n t s and p o s s i b l e f a u l t s .

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T h r u s t F a u l t s

The h i s t o r y o f t h e S i l v e r R e e f m i n i n g a r e ah a s b e e n one o f c o n t r o v e r s y c o n c e r n i n g t h e p r e s -

ence o r a b s e n c e o f a f a u l t b e t w e e n th e White Reefand t h e Buckeye Reef . In o r d e r t o f a i r l y approacht h e s o l u t i o n of th e problem a c a r e f u l s t r a t i g r a p h i cand s t r u c t u r a l s t u d y of t h e r o c k s be tween th e twor e e f s was made. In t h e f o l l o w i n g p a r a g r a p h s mucho f t h e d a t a c o l l e c t e d i n t h i s s t u d y i s b r i e f l ys u m m a r i z e d .

D e t a i l e d work on t h e s t r a t i g r a p h y o f t h e

White and Buckeye Reefs i n d i c a t e s a s t r i k i n g s i m i l -a r i t y i n s e q u e n c e o f r o c k l a y e r s . Summar i zedb e l o w a r e t h e i m p o r t a n t l i k e n e s s e s .

a . Approx imate ly th e same t h i c k n e s s of S i l v e rReef s a n d s t o n e , va ry ing only i n th e amounto f Tecumseh and Leeds s a n d s t o n e , o c c u r son b o t h r e e f s .

b . A d i s t i n c t i v e p i t t e d w e a t h e r i n g s a n d -s t o n e as much as e i g h t or more f e e t t h i c ko c c u r s a t t h e b a s e o f e a c h r e e f ( s e eP l a t e V I , B ) .

c . A p p r o x i m a t e l y e i g h t f e e t be low t h e b a s eo f e a c h r e e f i s a c h a r a c t e r i s t i c r e d -b a n d e d j a s p e r f rom one t o s i x i n c h e st h i c k i n c l u d e d i n 25 f e e t c ~ g r e e n i s ht o r e d d i s h s h a l e s .

d . D i s t i n c t i v e b r i c k r e d s a n d s t o n e beds 40f e e t t h i c k i n c l u d e a w h i t e s i l i c e o u sl i m e s t o n e l e d g e f rom 2" t o 1 2 " t h i c k .T h i s p r o b a b l y r e p r e s e n t s t h e " P r i d e o ft h e West Ledge" of R o l k e r (p . 2 4 , 1 8 8 1 ) .C a r e f u l s e a r c h , h o w e v e r, r e v e a l e d t h e

l e d g e u n d e r b o t h r e e f s i n c o n t r a s t t oR o l k e r ' s o r i g i n a l s t a t e m e n t .

e . A f l u f f y w e a t h e r i n g , p u r p l i s h b e n t o n i t i cs h a l e occur s below th e d e e p - r e d sands tonea n d s h a l e s o f b o t h r e e f s , t h o u g h t h et h i c k n e s s v a r i e s s o m e w h a t .



P l a t e VII . THRUST FAULTS

A. Smal l o v e r t h r u s t i n a d i t j u s t s o u t h ofA. S. & R. s h a f t , n e a r Leeds , Utah .

B. F l a t f a u l t i n i n c l i n e , 800 f e e t s o u t hof Savage S h a f t , n e a r Leeds , Utah .

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In t h e d e t a i l e d mapping o f t h e r e e f s c e r t a i ns t r u c t u r a l f e a t u r e s a t v a r i a n c e w i t h t h e g e n e r a ls t r u c t u r a l p a t t e r n w e r e o b s e r v e d . T h e s e a r es u m m a r i z e d b e l o w :

a . A s m a l l s y n c l i n e 15 0 f e e t wide o c c u r sj u s t n o r t h o f t h e A.S .& R. r o a d i n t h ev a l l e y . The s t r u c t u r e i s a n o ma lo u s i nan a r e a o f g e n e r a l l y c o n s i s t e n t s t r i k eand d i p s .

b . On t h e wes t s i d e o f t h e v a l i e y , s o u t h oft h e A.S.& R. r o a d , two h i l l s which t r e n dp a r a l l e l t o t h e power l i n e a r e composedo f w h i t e t o l a v e n d e r s a n d s t o n e s i m i l a ri n a p p e a r a n c e and c o m p o s i t i o n t o t h eTecumseh and Leeds s a n d s t o n e s . The n o r t hh i l l i s h i g h l y s h e a r e d and b r o k e n . Vi s -i b l e b e d d i n g t r e n d s a t r i g h t a n g l e s t ot h e p r e v a i l i n g s t r i k e o f t h e o t h e r s e d i -menta ry beds i n t h e v a l l e y .

c . The s o u t h h i l l a l s o shows ex t r eme s h e a r -i n g i n t h e s a n d s t o n e . Leeds ( ? ) s a n d -s t o n e l i e s o v e r t h e Tecumseh ( ? ) i n a

r e v e r s e r e l a t i o n s h i p . A s h a f t on t h ew e s t s i d e o f t h e h i l l which s h o u l d ha vec u t a minimum o f 30 f e e t o f s a n d s t o n ep a s s e d c o m p l e t e l y t h r o u g h t h e b l o c k i na few f e e t and i n t o t h e u n d e r l y i n g r e ds h a l e s . Near th e s o u t h end o f t h e h i l la s h e a r zone w i t h p r o m i n e n t b r e c c i a t i o nd i p s 250 t o t h e w e s t .

d . P r o m i n e n t d r a g f o l d s o c c u r i n t h e r e ds h a l e s t o th e sou th o f th e h i l l d e s c r i b e dabove . The f o l d s a r e s m a l l , r a n g i n g t o40 f e e t i n wid th and 100 i n l e n g t h . A llo f t h e minor f o l d s a re o v e r t u r n e d t o t h ee a s t . T h e s e a r e u n u s u a l f o r an a r e awhere s h a l e s and s a n d s t o n e s show no i n -d i c a t i o n o f i n t r i c a t e f o l d i n g .

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e . S o u t h o f t h e C a l i f o r n i a mine e x t r e m es h e a r i n g o f more m a s s i v e g r a y t o b u f fs a n d s t o n e beds and " c u t t i n g o u t " of d i f -f e r e n t s m a l l b e d s o f t h e r e d s h a l e ands a n d s t o n e s e r i e s o c c u r .

f . The Buckeye R e e f c o m p l e t e l y d i s a p p e a r s4 , 0 0 0 f e e t s o u t h of t h e C a l i f o r n i a mineand c r o p s o u t a g a i n one and a h a l f m i l e ss o u t h o f H a r r i s b u r g . S p r i n g s o c c u ra t t h e p o i n t o f d i s a p p e a r a n c e o f t h eBuckeye R e e f . To t h e n o r t h o f t h e o u t -c rop n e a r H a r r i s b u rg s m a l l r e v e r s e f a u l t sa re exposed i n a l a r g e wash.

g . S m a l l o v e r t h r u s t f a u l t s o c c u r i n t h eLeeds Mine on t h e White R e e f , i n a s m a l la d i t 400 f e e t sou thward on t h e road fromt h e A.S.& R. s h a f t , 1 , 1 0 0 f e e t s o u t h oft h e Savage s h a f t , 900 f e e t n o r t h e a s t o ft h e s h a f t i n an i n c l i n e , and i n p i t s on

t h e e a s t s i d e o f Tecumseh H i l l . In a l lc a s e s e x c e p t o n e , t h e o v e r t h r u s t i s t ot h e e a s t . The e x c e p t i o n i s t h e f a u l ts o u t h e a s t o f t h e S a v a g e s h a f t which i sd i s c u s s e d b e l o w.

C o n s i d e r i n g t h e above s t r a t i g r a p h i c ands t r u c t u r a l c o n d i t i o n s w h i c h e x i s t i n t h e a r e a ,f o u r p o s s i b l e e x p l a n a t i o n s m i g h t be a d v a n c e d t o

a c c o u n t f o r t h e m :

1 . T h e r e i s no f a u l t b e t w e e n t h e r e e f s .The r e p e t i t i o n o f t h e s i m i l a r b e d s i st h e r e s u l t o f l i k e s e d i m e n t a t i o n c o n d i -t i o n s w h i c h r e s u l t e d i n a l m o s t i d e n t i -c a l b e d s o f w h i t e t o r e d s a n d s t o n e s ands h a l e s b e i n g d e p o s i t e d . The d i f f e r e n ts t r u c t u r a l a n o m a l i e s p r o b a b l y r e s u l t e dd u r i n g t h e f o l d i n g o f t h e r o c k s .

2 . A n o r m a l f a u l t b e t w e e n t h e r e e f s , w i t ha d o w n d r o p t o t h e e a s t , h a s r e p e a t e dt h e s e c t i o n .

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3. A s t e e p ~ e s t d i p p i n g r e v e r s e f a u l t o c c u r sb e t ~ e e nt h e r e e f s . R e p e t i t i o n o f t h eb e d s i s t h e r e s u l t o f an u p t h r o ~ n~ e s t

b l o c k .

4. A t h r u s t f a u l t o f 200

-4 00

e x i s t s b e t ~ e e nt h e r e e f s .h a s b e e n t h r u s t t o t h eB u c k e y e R e e f .

d i p t o t h e ~ e s tThe ~ e s t b l o c k

e a s t o v e r t h e

R o l k e r , B u t l e r , B a l l , and o t h e r s s u g g e s t e dt h a t t h e s i m i l a r i t y i n t h e s t r a t i g r a p h y o f t h et ~ o r e e f s ~ a s th e r e s u l t o f s i m i l a r s e d i m e n t a t i o nc o n d i t i o n s . R o l k e r ( p . 3 4 , 1 8 8 1 ) ~ a s f i r s t t o

p u b l i s h h i s v i e ~ s on t h e a b s e n c e o f a f a u l t b et ~ e e nt h e r e e f s :

I have p u r p o s e l y b e e n e x p l i c i t i n d e sc r i b i n g t h e c i r c u i t s o f t h e r e e f s , b ec a u s e t h e t h e o r y has been advanced t h a tth e Buckeye and B u t t e Reefs were i n t u r nf a u l t e d from th e o r i g i n a l r e e f , th e WhiteReef , on i t s wes t s i d e and t h a t on ly oner e e f ex i s t ed on the e a s t s ide of th e h o r s eshoe ( the a n t i c l i n e ) . Aside from th e f a c tt h a t th e two r e e f s a re seen on t h e e n t i r ec i r c u i t , t h e r e a re o t h e r r e a s o n s whichs p e a k a g a i n s t a o n e - r e e f t h e o r y . Witht h e i r s i d e s 300-1500 f e e t a p a r t , g r a d ua l l y ~ i d e n i n gu n t i l t h e gap i s a b o u t4 , 0 0 0 f e e t , o r more a t t h e he a d o f t h ec u r v e , i t would be a v e r y s t r a n g e f a u l ti f we assumed i t t o have f a l l e n o f f t h eWhite ,Reef , i n t h e shape o f a ho r se shoe .But a g a i n , u n d e r l y i n g t h e White Reef i st h e P r i d e o f t h e West Ledge , s i l i c e o u sl i m e s t o n e , very p l a i n l y marked, and t o beseen d i s t i n c t l y a t th e f i r s t g l a n c e , a l la long th e White Reef . Th i s marked d i st i n c t i v e b ed i s a b s e n t i n t h e BuckeyeR e e f . F u r t h e r , t h e c h a r a c t e r o f t h eBuckeye and White Reef ore s i s as d i f f e re n t t o t h e e x p e r i e n c e d eye as d a r k b l u ei s f rom p u r p l e and t h e y a c t d i f f e r e n t l yi n t h e m i l l .

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n o r t h v e s t f l a n k of t h e Vi r g i n a n t i c l i n e . Thoughhe does n o t ment ion th e r e e f s d i r e c t l y , th e f a u l t e ds a n d s t o n e l e d g e m a k e r s h o v n on h i s map w e s t o fLeeds undoub ted ly r e p r e s e n t s th e S i l v e r Reef s a n d -s t o n e .

Tvo o t h e r p o s s i b i l i t i e s e x i s t : th e h igh ang ler e v e r s e f a u l t and th e lo v ang le t h r u s t p o s s i b i l i t y .Curso ry e x a m i n a t i o n o f t h e a e r i a l p h o t o g r a p h s o fth e Leeds a r e a would i n d i c a t e t h a t e i t h e r a normalf a u l t o r r a p i d l y l e n s i n g b e d s c o u l d a c c o u n t f o rt h e a n o m a l i e s . More c a r e f u l s t u d y o f th e p h o t ographs , hovever, vould shov t h a t any p o s s i b l e f a u l tbe tween t h e r e e f s must be a t l e a s t 400 f e e t e a s tof t h e A.S.& R. s h a f t s i n c e a c o n t i n u o u s u n f a u l t e ds e c t i o n of T r a i l H i l l s a n d s t o n e and s h a l e c an bet r a c e d i n t h e f i e l d f o r a c o n s i d e r a b l e d i s t a n c ea long t h e s t r i k e of t h e White R e e f . Ye t , u n d e rground v o r k i n g s i n t h e Buckeye R e e f v e r t i c a l l ybelow such a minimum d i s t a n c e f a i l e d t o shov anyd i sp l acemen t of th e beds . These same beds of s a n d -s t o n e v e r e s t i l l p r e s e n t a t t h e f a c e o f th e d r i f t sc o n s i d e r a b l y t o t h e v e s t o f any p o s s i b l e n o r m a lf a u l t d i p p i n g t o th e e a s t . T h e r e f o r e , any f a u l t ,i f one be p r e s e n t , mus t h a v e a v e s t v a r d d i p andt h e movement , of n e c e s s i t y , must be of a r e v e r s et y p e . The s h a f t v h i c h v a s sunk by t h e A.S .& R.

Company i n 1 9 2 9 , c u t t h e Buckeye R e e f a b o u t 350f e e t below th e c o l l a r . Tha t t h i s c o u l d have beena n o t h e r s a n d s t o n e bed t h a n t h e Buckeye Reef wasc o n s i d e r e d , b u t a d r i f t t o t h e e a s t v i t h r a i s e sfrom i t t o th e sands tone above and t hen a c o n n e c t -in g i n c l i n e i n t o t h e o ld Savage Mine s t o p e s l e f tl i t t l e doubt t h a t th e sands tone bed was th e BuckeyeR e e f e x t e n s i o n . S i n c e t h e f u l l s e c t i o n o f t h eBuckeye Reef s i l v e r - b e a r i n g s a n d s t o n e i s exposedi n th e s h a f t , any f a u l t t o e x p l a i n such a c o n d it i o n must have a d i p from t h e minimum w e s t p o s it i o n on t h e s u r f a c e t o a t l e a s t t h e t o p o f t h ee x p o s u r e i n t h e s h a f t . P r o j e c t i o n of a l i n e b etween t h e s e tv o p o i n t s y i e l d s a maximum p o s s i b l ed i p o f 30 0 W. Thus , any such f a u l t m u s t be i n a

low a n g l e t h r u s t c a t e g o r y .

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B r i e f l y summar i zed , t h e n , t h e s t r a t i g r a p h i cs i m i l a r i t i e s i n t h e b e d s , e s p e c i a l l y t h e j a s p e rb e d , a one f o o t t h i c k s i l i c e o u s l i m e s t o n e b e d ,and p u r p l e s h a l e s below e a c h r e e f , and t h e s t r u ct u r a l e v i d e n c e i n th e form o f f o l d s , and more imp o r t a n t , i n s m a l l t h r u s t f a u l t s , t h e p r e s e n c e o fs p r i n g s a long t h e p r o p o s e d t r a c e , and th e l e n s i n go f beds a g a i n s t an o v e r l y i n g s e r i e s , s t r o n g l y s u gg e s t an o v e r t h r u s t f a u l t b e t w e e n t h e Buckeye andWhi te R e e f s . F i n a l l y , e v i d e n c e i n t h e A.S.& R.s h a f t w o r k i n g s shows t h a t t h e b e d s have changedi n d i p f rom 30 oW. t o a few d e g r e e s e a s t w h i l e th eo v e r l y i n g b e d s a t t h e s u r f a c e a l l d i p 30 o -3 5 0 W.

The s t r i k e o f t h e f a u l t a p p r o x i m a t e s t h a t o f t h ebeds and t h e t r a c e can be fo l lowed over a d i s t a n c eo f s i x m i l e s .

D i s p l a c e m e n t on t h e f a u l t i s d i f f i c u l t t oe s t i m a t e . I f i t b e assumed t h a t t h e d i p o f t h ef a u l t i s c o n s i s t e n t , t h e d i p - s l i p d i s p l a c e m e n tmay be s e v e r a l t housand f e e t as t h e beds and f a u l ta r e p a r a l l e l . H o w e v e r, f l a t t e n i n g o f t h e d i po f t h e b e d s o f t h e White Reef by d r a g may y i e l da d i p - s l i p d i s p l a c e m e n t of a t l e a s t 1 ,300 f e e t and

p o s s i b l y much more. .The q u e s t i o n may w e l l be asked why th e f a u l t

was n o t r e c o g n i z e d by o t h e r i n v e s t i g a t o r s i n t h ea r e a . S e v e r a l f o r t u i t o u s o c c u r r e n c e s make anyf a u l t i n t h e a r e a , e x c e p t t h o s e c u t t i n g d i s t i n c t l yd i s s i m i l a r r o c k s d i f f i c u l t t o f i n d . The f a u l t b etween th e two r e e f s i s e n t i r e l y w i t h i n s o f t , e a s i l yw e a t h e r e d , d e e p - r e d t o b r i c k - r e d s h a l e s and minor

s a n d s t o n e s . The Duff in , l ower T r a i l H i l l sands toneand s h a l e s , and H a r t l e y s h a l e s and s a n d s t o n e a r ea l m o s t i d e n t i c a l i n l i t h o l o g y and c o l o r . A l s ot h e f a c t t h a t t h e s h a l e s h a v e b e e n v e r y l i t t l e

deformed i n th e f a u l t i n g p r o c e s s , t h a t no f o s s i l se x c e p t p a r t s o f t r e e s a r e known, and t h e knownr a p i d l e n s i n g of i n d i v i d u a l beds w i t h i n th e Tr i a s s i cs e c t i o n c o u l d w e l l have caused most i n v e s t i g a t o r st o c o n c l u d e t h a t no f a u l t e x i s t e d .

T h r u s t S o u t h e a s t o f Savage S h a f t

A t h r u s t f a u l t o f s m a l l d i s p l a c e m e n t o c c u r s1 200 f e e t s o u t h of t h e Savage s h a f t on th e Buckeye,

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Reef ( s e e p l a t e I I ) . Where th e t r a c e o f t h e f a u l tc u t s t h e c r e s t o f t h e R e e f o b s e r v a b l e d i p - s l i pd i s p l a c e m e n t i s 5 0 - 7 0 f e e t . At t h e f a u l t , th es a n d s t o n e s a re somewhat s h e a r e d and b r o k e n , thoughj u s t above i t , t h e o v e r r i d i n g n o r t h b l o c k showsp r a c t i c a l l y no s h e a r i n g . J o i n t s a re s t i l l p r o m in e n t i n t h e h a n g i n g w a l l , b u t t h e f o o t w a l l o fTecumseh sands tone t o t h e s o u t h i s h i g h l y s h e a r e d .J o i n t s , t hough p r e s e n t i n t h i s b l o c k , a r e s c a r c eand a p p e a r t o have been d e s t r o y e d by t h e d e f o r m at i o n .

The t h r u s t f a u l t can be t r a c e d 200 f e e t downt h e e a s t f a c e o f t h e Buckeye R e e f where i t d i p sa p p r o x i m a t e l y 36°N. On t h e d i p s l o p e o f t h e

Buckeye R e e f t h e f a u l t i s p a r t l y c o v e r e d w i t hdumps , b u t i t i s v i s i b l e i n t h e s h a f t s n e a r b y .An i n c l i n e d s h a f t j u s t n o r t h o f t h e f a u l t on t h eB o u l d e r Al luv ium c o n t a c t shows a f l a t f a u l t c u tt i n g s t e e p l y d i p p i n g Tecumseh beds ( s e e P l a t e V I I ,B). This i s th e l a s t v i s i b l e ev idence of th e f a u l tto th e n o r t h .

Apparen t d i s p l a c e m e n t on t h e f a u l t i s t o th es o u t h , b u t w h e t h e r t h i s was t h e a c t u a l d i r e c t i o no f movement c o u l d n o t be d e t e r m i n e d . The s m a l lt h r u s t i s p r o b a b l y r e l a t e d i n t i m e t o t h e maint h r u s t d e s c r i b e d a b o v e .

Age of F a u l t s

From d i r e c t f i e l d e v i d e n c e i n t h e d i s t r i c tth e age of th e f a u l t s must range be tween p o s t - U p p e rT r i a s s i c and p r e - l a t e P l e i s t o c e n e (? ) , s i n c e t heyc u t Chinle rocks and are covered by t e r r a c e d e p o s i t so f p r o b a b l e l a t e - P l e i s t o c e n e age . However, o t h e rr e l a t i o n s h i p s w i t h i n t h e d i s t r i c t a re s u g g e s t i v eo f a more s p e c i f i c age t h a n t h e p o s s i b l e widerange c i t e d above. Gardner (p . 250, 1941) s u g g e s t st h a t f o l d i n g , which probab ly i n c l u d e d th e f o r m a t i o no f t h e Vi rg i n a n t i c l i n e , o c c u r r e d d u r i n g t h e L a r amide Revolu t ion i n l a t e Cre taceous o r e a r l y Te r t i a r y

t i m e . Since bo th normal and t h r u s t f a u l t s c u t t h em a j o r f o l d and t h e s u b s i d i a r y f o l d s t o t h e w e s t ,t h e s e f a u l t s may be c o n t e m p o r a n e o u s o r p o s t - f o l di n a g e .

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The c l o s e s p a t i a l r e l a t i o n s h i p o f t h e normalf a u l t s on t h e nose of t h e Vi r g i n and Leeds a n t ic l i n e s u g g e s t s a g e n e t i c c o n n e c t i o n t o t h e f o l di n g . Thi s i s borne ou t when i t i s n o t e d t h a t th e

f a u l t s a r e o f s m a l l a r e a l e x t e n t and a p p a r e n t l ya r e a l m o s t l i m i t e d t o t h e more c o m p e t e n t S i l v e rR e e f s a n d s t o n ~s h a l e s and t h i n s a n d s t o n e s . Asment ioned above, t h e s e t ypes of s t r u c t u r e a re q u i t es i m i l a r t o t h e e p i - a n t i c l i n a l f a u l t s d e s c r i b e d byI r w i n (p. 11 9 , 1926) and may r e p r e s e n t s t r u c t u r a la d j u s t m e n t s o f a more c o m p e t e n t member w i t h i n as e r i e s o f s h a l e s a t t h e t i m e o f t h e f o l d i n g .

As none o f t h e l a r g e r n o r m a l f a u l t s e x t e n di n t o t h e t h r u s t f a u l t zone no ag e r e l a t i o n s h i pc o u l d be e s t a b l i s h e d b e t w e e n t h e two t y p e s off a u l t i n g . However, some o f t h e s m a l l e r t h r u s tf a u l t s on th e Buckeye Reef a re d i s p l a c e d by s t e e p l yd i p p i n g normal f a u l t s . I t i s p o s s i b l e , of c o u r s e ,t h a t t h e s e d i s l o c a t i o n s c o u l d have o c c u r r e d j u s tf o l l o w i n g t h e t h r u s t i n g o r a g a i n a t a much l a t e rt i m e , b u t e i t h e r way i t i n d i c a t e s t h a t some normal

f a u l t s o c c u r r e d a f t e r t h e t h r u s t i n g . Ye t , t h eprominent s h e a r and s m a l l f a u l t e x t e n d i n g from th eC a l i f o r n i a mine n o r t h w a r d i s c u t o f f on to p by af l a t t h r u s t 800 f e e t s o u t h o f t h e Savage s h a f t .Thi s i s i n d i c a t i v e o f a p r e - t h r u s t age . Thus , i t

a p p e a r s t h a t two p e r i o d s o f n o r m a l f a u l t i n g o c -c u r r e d i n t h e d i s t r i c t . Which age o f f a u l t i n gc o r r e s p o n d s w i t h th e more numerous f a u l t s on t h eVi r g i n a n t i c l i n e n o s e i s n o t known.

The n e a r e s t t h r u s t f a u l t i n g i s t h a t d e s c r i b e dby Dobbin ( p . 1 3 1 , 1939) i n which he obse rved twop e r i o d s o f t h r u s t f a u l t i n g s o u t h o f S t . George ,U t a h . One t h r u s t o f c o n s i d e r a b l e m a g n i t u d e o c -c u r r e d i n Eocene t i m e . I t was l a t e r d i s l o c a t e dby n o r m a l f a u l t s . He a l s o r e c o r d s a p o s t - M i ocene (? ) t h r u s t 14 m i l e s wes t o f S t . George wherer o c k s o f e a r l y M i s s i s s i p p i a n age a r e t h r u s t overMiocene (? ) conglomerate . Since both of th e t h r u s t sd e s c r i b e d a r e many m i l e s s o u t h w e s t o f Leeds t h e yc a n n o t be r e l a t e d d i r e c t l y t o t h e s m a l l t h r u s t a tS i l v e r R e e f .

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The p o s s i b i l i t y e x i s t s t h a t t h e s m a l l t h r u s tbe tween th e White and Buckeye R e e f s o r i g i n a t e d a tt h e t ime of t h e f o r m a t i o n of t h e Vi r g i n a n t i c l i n eand i t s a s s o c i a t e d s m a l l e r f o l d s . Such a t h r u s t

may have r e s u l t e d when t h e f u n d a m e n t a l s t r e n g t hof t h e r o c k s was exceeded by t h e s t r e s s e s . Ye t ,d u r i n g t h i s f o l d i n g p e r i o d , t h e now f a u l t e d bedswere covered by s e v e r a l thousand f e e t o f J u r a s s i c ,C r e t a c e o u s and p o s s i b l y Eocene b e d s . However, i f

i t be c o n s i d e r e d t h a t th e t h r u s t b e t w e e n th e r e e f si s a r e s u l t o f r e n e w a l o f s t r e s s e s on t h e m a j o rf o l d a f t e r e r o s i o n had removed much of th e J u r a s s i c ,C r e t a c e o u s , and Te r t i a r y c o v e r , t h e t h r u s t would

seem more l i k e l y t o o c c u r i n t h e s t r a t i g r a p h i cp o s i t i o n t h a t i t d o e s and wou ld r e p r e s e n t t h el a t e s t e x p r e s s i o n of f a u l t i n g i n t h e S i l v e r Ree fa r e a .

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ECONOMIC GEOLOGY

HISTORY

Though high grade s i l v e r f l o a t was d i scove redi n 1869 i n th e S i l v e r Reef a r e a , i t was no t u n t i l1875 t h a t r i c h ore was found i n p l a c e and a c t i v emining was s t a r t e d . Even t hen th e "boom" p e r i o d ,so common t o w e s t e r n m i n i n g camps , d i d n o t g e tu n d e r way u n t i l 1877 and l a s t e d only u n t i l 1888when company o p e r a t i o n c e a s e d . The u s u a l p e r i o dof min ing by l e s s e e s fo l lowed b u t ended by 1909 .S e v e r a l r e - e x a m i n a t i o n s of t h e d i s t r i c t have beenmade i n l a t e r y e a r s b u t t h e r e has been a lmos t nop r o d u c t i o n u n t i l t h e r e c e n t (1950 ) uran ium o res h i p m e n t . As n e a r l y as e x i s t i n g r e c o r d s can bei n t e r p r e t e d , th e p r o d u c t i o n of t h e d i s t r i c t f rom1875 t o 1910 i s va lued a t $7 ,822 ,900 which i s a l sor o u g h l y t h e amount i n ounces of s i l v e r mined ands h i p p e d . I n t e r e s t i n g d e t a i l s of t h e h i s t o r y andp r o d u c t i o n seem wor th r e c o r d i n g and a re s e t f o r t hi n th e f o l l o w i n g p a r a g r a p h s .

I n 1 8 6 9 , John Kemple ,a

p r o s p e c t o r , founds i l v e r f l o a t n e a r H a r r i s b u r g , Utah, which assayed$17 ,000 t o t h e t o n . The d i s c o v e r y caused c o n s id e r a b l e exc i t emen t i n the a r e a , bu t no d i s c o v e r i e so f o re i n p l a c e were made a t t h a t t i m e . H. C.

Burchard (p . 268, 1883) noted t h a t i n 1871 , " theUnion d i s t r i c t was o rg a n i z e d and 16 l o c a t i o n s orc l a i m s were r e c o r d e d which , however, were s u b s eq u e n t l y a b a n d o n e d . " On June 22-23 , 1874, th e code

or laws and c o n s t i t u t i o n of th e H a r r i s b u rg miningd i s t r i c t were w r i t t e n and adop ted . The d i s t r i c ti n c l u d e d an a r e a o f 1 4 4 s q u a r e m i l e s w i t h t h eH a r r i s b u r g s c h o o l as t h e c e n t e r p o i n t . Orson B.Adams became th e f i r s t d i s t r i c t r e c o r d e r and d u ri n g t h e r e m a i n d e r o f 1874 r e c o r d e d t w e n t y - s e v e nc l a i m s .



In A p r i l and May of 1875 , s e v e r a l p r o s p e c t o r sa r r i v e d f rom S a l t Lake C i t y , b u t t h e i r work i nt h e d i s t r i c t was u n s u c c e s s f u l and t h e y a r e r ep o r t e d t o have l e f t t h e camp i n d i s g u s t . I t h as

been c la imed t h a t t h e a r r i v a l o f Wil l i am TecumsehB a r b e e i n J u l y 1 8 7 5 , p r o b a b l y was t h e g r e a t e s ts t i m u l u s t o d i s c o v e r y i n t h e d i s t r i c t . He p r o spec ted t h e White Reef n o r t h o f th e p r e s e n t Barbeeand Walker mine wi thou t succe s s . He l e f t th e campbu t r e tu rned i n the f a l l of 1875, when he c a r e f u l l yp r o s p e c t e d t h e Tecumseh H i l l s e c t i o n . Accordingt o Mr. O s c a r McMul l in , ( p e r s o n a l c o m m u n i c a t i o n ,Dec . , 1 9 4 8 ) , a fo rmer m i n e r i n t h e o ld camp, t h e

o r i g i n a l d i s c o v e r y o f r i c h o re i n p l a c e was madeby Barbee who n o t e d an o u t c r o p o f 300-400 ounces i l v e r which had b e e n gouged o u t by t h e w h e e l sof Joe and Alex McCleave ' s wood wagon on th e e a s ts ide of Tecumseh H i l l . This f ind s t a r t e d th e f i r s tknown mining i n th e d i s t r i c t .

By December 8 , 1875 , t e n and one h a l f t ons o fo re had been s h i p p e d t o S a l t Lake Ci ty s m e l t e r s .

According t o Rolker (p . 3 0 , 1 8 8 1 ) , th e s o r t e d o rer a n $502 per ton . A second sh ipment 45 days l a t e rwas v a l u e d a t $ 7 , 0 0 0 n e t . High s h i p p i n g ands m e l t e r r a t e s and o t h e r m i s c e l l a n e o u s c h a r g e s a tth e S a l t Lake S m e l t e r s made i t imposs ib l e t o sh ipany th ing bu t th e very r i c h e s t of ore . B e t t e r r a t e swere o b t a i n e d i n P i o c h e , Nevada, which was i n i t sd e c l i n i n g s t a g e of h i g h - g r a d e s i l v e r p r o d u c t i o n ,and s h i p m e n t s t o t h a t town began i n J u l y , 1876 .

Other s t h a n Barbee were mining i n th e S i l v e r Reefa r ea a t t h i s t ime f o r Rolker (p . 3 0 , 1881) r e co rdst h a t $8,000 was pa id t o " o u t s i d e r s . " Up t o O c to b e r , 1 8 7 6 , Barbee n e t t e d $ 1 7 , 0 0 0 f rom t h e S a l tLake s m e l t e r s and $23 ,000 f rom P i o c h e .

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I t i s e s t i m a t e d t h a t on ly 12 p e r s o n s made upt h e p o p u l a t i o n of t h e camp u n t i l November, 1876 .L i t i g a t i o n i n t h e Pioche m i n e s , and p o s s i b l y much

u n e m p l o y m e n t f r o m t h e end o f t h e "boom" m i n i n gt h e r e , b r o u g h t s u c h a r u s h of m i n e r s t o S i l v e rR e e f t h a t i t was t e r m e d t h e " P i o c h e S t a m p e d e . "The p o p u l a t i o n of t h e new town r a p i d l y i n c r e a s e dand min ing b e g a n i n e a r n e s t .

The f i r s t c l a i m t o b e s u r v e y e d f o r p a t e n twas i n May, 1 8 7 7 . An i n t e r e s t i n g s i d e l i g h t i st h e comment o f t h e U. S. Deputy m i n e r a l s u r v e y o r,F. D i c k e r t (P. 1 1 , 1 8 7 7 ) , who s t a t e s :

S t o n e w a l l Jackson c l a i m , owned and c l a i m -ed f o r p a t e n t by Gisborn of S a l t Lake C i t y,U t a h . Loca ted March l a , 1875 . Surveyedf o r p a t e n t May 30 and 3 1 , 1 8 7 7 , a f t e rb e i n g f o r c i b l y e j e c t e d on t h e 1 9 t h and2 1 s t o f May, 1877 by th e p a r t i e s a t p r e -s e n t i n p o s s e s s i o n of th e ground . 3

I t a p p e a r s t h a t o w n e r s h i p r i g h t s on c l a i m sh i g h l y d i s p u t e d i n t h i s d i s t r i c t as i nt h e o t h e r w e s t e r n m i n i n g camps o f t h e

Mr. D i c k e r t a l so e s t a b l i s h e d Uni ted S t a t e s

w e r e asmany o fp e r i o d .Minera lo n t h eo f t h e

c l a i m s

Monument N o . 1 , on Tecumseh H i l l , and No. 2v o l c a n i c c o n e on t h e E a s t R e e f , n o r t hD u f f i n m i n e . A l l l a t e r p a t e n t s u r v e y

w e r e t i e d t o t h e s e m o n u m e n t s .With t h e m i n i n g o f t h e h i g h g r a d e o r e s and

p r o m i s e o f good p r o f i t s , ' s e v e r a l min ing and m i l -l i n g compan ie s were o rg a n i z e d and c o n t r o l g a i n e do f th e i m p o r t a n t c l a i m s . The Leeds Company, wi thf o u r c l a i m s r e s t r i c t e d t o t h e White Reef and t h ef i r s t m i l l , was o rg a n i z e d i n t h e autumn o f 1877 .

3 Note t h a t t he c l a im was s t a k e d b e f o r e th e a r r i v a lo f W. T. Barbee i n th e d i s t r i c t .







r ecove red up t o 86% o f 2 0 . 6 3 ounce o re on 10 ,000t o n s . The Barbee and Walker M i l l o n a run o f 5740t ons of 29 .10 ounce ore r e c o v e r e d 79.7% of Assayv a l u e . The Leeds Company averaged 79.4% r ecove ry

on 12,000 t ons of 19 .42 ounce o r e . The above f i g -u r e s r e p r e s e n t r e c o v e r y d u r i n g t h e h ~ i g h to f th emining boom. I t i s p o s s i b l e t h a t t a i l i n g l o s s e sf o r t h e e n s u i n g p e r i o d s f o l l o w i n g 1880 may havebeen l e s s due t o i m p r o v e d m i l l i n g m e t h o d s . No

l a t e r r e c o r d s a r e a v a i l a b l e , howeve r.

Mining c o s t s r anged f rom $4 .50 t o $9 .50 p e rto n depend ing on th e l o c a l i t y of th e mine , amount

o f p r o s p e c t i n g o r d e v e l o p m e n t w o r k , dead work ,w a t e r , and o t h e r f a c t o r s . R o l k e r ( p . 3 2 , 1 8 8 1 )s t a t e s t h a t t h e t o t a l c o s t o f t h e o r e s i n 1880 ,i n c l u d i n g t h e b u l l i o n c h a rg e s r anged f rom $ 1 4 . 0 0t o $17 .00 p e r t o n . These f i g u r e s a re p robab ly amaximum and r e p r e s e n t company o p e r a t i o n . Lesseeswere ab le t o mine a t a much l o w e r c o s t p e r t o n .H a r t l e y ( p e r s o n a l c o m m u n i c a t i o n ) r e p o r t s t h a tc h l o r i d e r s mined o re wor th $ 1 0 . 0 0 a t a p r o f i t i n

1890. For a summary of mining and o p e r a t i n g c o s t so f th e S t o r m o n t Company, t h e r e a d e r i s r e f e r r e dt o th e E n g i n e e r i n g and Mining J o u r n a l o f Janua ry24 , 1880 .

The mining method employed was shr inkage s t o p -i n g , and m i n o r unde rhand s t o p i n g . S t o p e w a l l swere suppor ted by s t u l l s and f i l l s o f b r o k e n rockand low g r a d e o r e . Most o f t h e m i n e s , e x c e p t

t h o s e w i t h l a r g e caved s t o p e s and t h o s e f i l l e dw i t h w a t e r , a r e s t i l l q u i t e a c c e s s i b l e a t t h ep r e s e n t t i m e .

As shown by f i g u r e 4, th e g r e a t e s t p e r i o d ofm i n i n g a c t i v i t y was f rom 1877 t o 1 8 8 8 . M a j o rcompany o p e r a t i o n s h ad c e a s e d b y 1 8 8 8 , t h o u g hc o n s i d e r a b l e mining by " c h l o r i d e r s " fo l lowed t h e i rc e s s a t i o n . E a r l y i n 1 8 9 2 , R. G. M c Q u a r r i e and

A l b e r t G r a n t l e a s e d t h e m i n e s and m i l l o f t h eC h r i s t y Company and s u b l e a s e d t o t h e c h l o r i d e r si n th e d i s t r i c t . Sudden d e c r e a s e s i n t h e p r i c eo f s i l v e r c a u s e d l o s s e s on f o r m e r l y p r o f i t a b l eo r e .

- 73 -



In 1 3 9 3 , Wooley, Lund, and J u d d , f o r m e r merc h a n t s of S i l v e r Reef ga ined c o n t r o l o f th e Barbeeand Walker mine , m i l l , and o t h e r p r o p e r t i e s . WithR. G. McQuar r ie as manage r, t h e Barbee and Walker

m i l l was c o n v e r t e d i n t o a more e c o n o m i c a l w a t e rd r i v e n p l a n t . P e n d l e t o n (p . 11 2 , 1 9 3 0 ) , a f o r m e rr e s i d e n t o f S i l v e r R e e f , c l a i m s t h a t b o t h t h el e s s e e and s u b - l e s s e e s made a p r o f i t . As f i g u r e4 s h o w s , h o w e v e r, t h e p r o d u c t i o n was n e g l i g i b l ecompared t o f o r m e r p e r i o d s .

In 1 8 9 8 , th e Brundage Company, of C l e v e l a n d ,Ohio, a c q u i r e d t h e Wooley, Lund, and Judd i n t e r e s t s

and most o f t h e o t h e r i m p o r t a n t mining p r o p e r t i e si n th e d i s t r i c t . However, f u r t h e r d e c l i n e s i n th ep r i c e o f s i l v e r d u r i n g t h e e n s u i n g t h r e e y e a r sb r o u g h t m i n i n g a l m o s t t o a s t a n d s t i l l . B u t l e r( p . 5 8 6 , 1 9 2 0 ) n o t e s t h e l a s t s i l v e r p r o d u c t i o na s 1 9 0 9 . A p p a r e n t l y , t h e l a s t m i l l ru n was madei n 1909 when H e i k e s ( p . 4 8 5 , Min. R e s . o f U . S . )r e p o r t s t h a t t h e " F r e e Coinage p r o p e r t y " ( B r u ndage Min ing and R e d u c t i o n Company) produced somes i l v e r b u l l i o n which was r e c o v e r e d i n a 5 - s t a m pa m a l g a m a t i o n m i l l .

In 1 9 1 6 , A. W. C o l b a t h a t t e m p t e d a r e v i v a lo f t h e d i s t r i c t . The S i l v e r R e e f C o n s o l i d a t e dMines was o r g a n i z e d and a l l t h e f o r m e r i m p o r t a n tc l a i m s i n t h e S i l v e r Reef a r e a were b r o u g h t u n d e rt h e c o n t r o l o f t h i s company. D e v e l o p m e n t workwas u n d e r t a k e n on t h e W h i t e R e e f and a l s o t h eBuckeye Reef w i t h e n c o u r a g i n g r e s u l t s a t th e Cobb

Mine. No p r o d u c t i o n i s r e c o r d e d f o r th e p e r i o d ,however. The r e m a i n i n g m i l l i n t h e d i s t r i c t wasd i s m a n t l e d and s o l d by t h e company.

During th e y e a r s 1 9 2 9 - 3 0 , t h e American S m e l ti n g and R e f i n i n g Company u n d e r t o o k c o n s i d e r a b l es a m p l i n g o f t h e o l d m i n e s on t h e Buckeye R e e f .A

t h r e e c o m p a r t m e n t 540 f o o t v e r t i c a l s h a f t wassunk a t t h e b a s e o f t h e Whi te R e e f s o u t h e a s t oft h e L e e d s mine s h a f t . D r i f t s , c r o s s c u t s , andr a i s e s were made on t h e 300 and 460 f o o t l e v e l st o c o n n e c t t o t h e o ld w o r k i n g s o f t h e Leeds Mineon t h e Whi te R e e f and t h e o l d S a v a g e s t o p e s ont h e Buckeye R e e f r e s p e c t i v e l y .



Mr. A. W. Newman, g e o l o g i s t f o r t h e Amer icanS m e l t i n g and R e f i n i n g Company, w r i t e s an i n t e r e s ti n g s i d e l i g h t on h i s p a r t i n t h e de v e l o p me n t work( P e r s o n a l Communica t ion , May 7 , 1 9 4 8 ) :

My m a i n j o b a t t h e t i m e was t o d i r e c tt h i s w o r k by p l u m b i n g t h e s h a f t andd o i n g t h e n e c e s s a r y s u r v e y i n g t o makea connec t i on with th e l owes t Savage s t o p eso i t c o u l d be u n w a t e r e d w i t h o u t k i ll i n g any m e n - - w h i c h i s a s t o r y i n i t -

s e l f a s i t was l i k e c o m i n g up u n d e r al a k e 200 f e e t d e e p .

The c o n n e c t i o n was made s u c c e s s f u l l y w i t h o u ti n j u r y t o any o f t h e men. A f t e r d e - w a t e r i n g o fa l l o f t h e o l d m i n e s , t h e company s a m p l e d t h ea c c e s s i b l e w o r k i n g s . With t h e c o n t i n u e d f a l l i nt h e p r i c e o f s i l v e r , t h i s was t h e l a s t m a j o r a tt e m p t t o open th e m i n e s o f t h i s u n i q u e d i s t r i c t .L a t e i n 1 9 4 6 , a p r i v a t e g r o u p s a m p l e d some o ft h e o l d dumps and d r i l l e d 3 d iamond d r i l l h o l e son t h e Buckeye Reef and 2 on t h e Whi te R e e f . I n

1 9 5 0 , a 8 . 6 8 t o n s h i p m e n t o f o re a v e r a g i n g 0.56%uran ium was made . C o n s i d e r a b l e p r o s p e c t i n g f o ruranium i s underway a t th e t ime o f t h i s p u b l i c a t i o n .

Produc t ion

The fo rmer main produc ing mines o f th e d i s t r i c ta re on th e White and Buckeye Reefs wi th l e s s i m p o rt a n t ones on t h e E a s t Reef . Beg inn ing a t th e n o r t h

en d o f t h e W h i t e R e e f and p r o c e e d i n g s o u t h t h em a i n p r o d u c e r s were t h e B a r b e e and Wa l k e r , t h eL e e d s , L e e d s # 2 , and t h e Thompson and Cobb a r e ai nc lud ing th e sm a l l e r mines McNally, Nicho l s , N e w t o n ~

and S o u t h Thompson. The Emily J ane p r o p e r t y l i e ss o u t h o f th e S o u t h Thompson mine . On t h e BuckeyeR e e f ( s e e f i g u r e 9) t h e mines f rom n o r t h on t h enose o f Tecumseh H i l l sou thward i n c l u d e th e S i l v e rF l a t , M a n h a t t o n , S a v a g e , B u c k e y e , K i n n e r , L a s t

C h a n c e , M a g g i e , C a l i f o r n i a , and S t o r m o n t . TheE a s t Ree f mi n es a r e l e s s e x t e n s i v e and p r o d u c e db u t a f r a c t i o n o f t h e t o t a l p r o d u c t i o n . These i nc l u d e t h e To q u e r v i l l e , Va n d e r b i l t , and D u f f i n .

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F i g u r e 4. P r o d u c t i o n c h a r t ,S i l v e r R e e f , U t a h , 1877-1910 .

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1905 1910



Var ious p r o d u c t i o n e s t i m a t e s have been madef o r th e d i s t r i c t r ang ing from $7,987,142, (p . 586,1920) t o over $17,000,000 (Crane , 1920) . B u t l e rand Heikes ' f i g u r e s probably are th e most accu ra t e .The i r g e n e r a l i z e d d a t a c h e c k c l o s e l y w i t h Wel l sF a rg o B u l l i o n s h i p m e n t s and e s t i m a t e s made byeng inee r s i n th e d i s t r i c t a t t h e t ime o f th e mini n g . They e s t ima t e a t o t a l p roduc t i on of 7,211,463ounces of s i l v e r .

The w r i t e r reviewed a l l of th e Repor t s o f theD i r e c t o r o f th e Mint from 1881 t o 1904 i n c l u s i v eand a r r i v e d a t a somewhat l o w e r f i g u r e . E r r o r si n r e c o r d i n g o u n c e s p roduced as n o t e d by We l l sFargo Company as s h i p m e n t s , and t h e t o t a l p r o d u ct i o n f i g u r e f o r

th ey e a r shows

ad i s c r e p a n c y i n

v a l u e o f a t l e a s t $ 3 1 8 , 0 6 1 . B a s e d on o u n c e sa lone , and an average s i l v e r p r i c e f o r each y e a r ,th e w r i t e r ' s t o t a l i s $7 ,504 ,861 .14 e x c l u s i v e o f1875-76 p r o d u c t i o n and $53 ,994 f o r 1901-1909 .However, us ing t o t a l p r o d u c t i o n f i g u r e s and adding$48,000 f o r 1875-76 one a r r i v e s a t a grand t o t a lo f $ 7 , 8 2 3 , 0 0 0 , 0 0 0 f o r t h e p e r i o d o f 1875-1910 .

The above d a t a have been summarized i n f i g -u r e 4. I t i s o f i n t e r e s t t o n o t e t h a t t h e d e -c r e a s e i n v a l u e of p r o d u c t i o n of s i l v e r o re p r e -ceded by 3-5 yea r s t he r a p i d drop i n t h e va lue off i n e s i l v e r p e r ounce . Major p r o d u c t i o n i n t h ed i s t r i c t , as t h e c u m u l a t i v e g r a p h s h o w s , t o o kplace i n th e r e l a t i v e l y s h o r t p e r i o d o f l e s s thans i x y e a r s . F o l l o w i n g t h i s t h e r e was an a l m o s tc o n t i n u a l dec rea se i n p r o d u c t i o n u n t i l i t s c e s s a -

t i o n i n 1909. High mi l l i ng c o s t s , m a t e r i a l s c o s t s ,t r a n s p o r t a t i o n , w a g e s , s t r i k e s , d e c l i n e i n t h ep r i c e o f s i l v e r and l o w e r s i l v e r c o n t e n t i n t h eo re have a l l been c i t e d as c o n t r i b u t i n g c a u s e sf o r t h e demise o f t h e camp, b u t t h e l a s t f a c t o rappea r s t o have been t h e g r e a t e s t .

I n d i v i d u a l p r o d u c t i o n r e c o r d s f o r t h e d i f -f e r e n t m i n e s a r e n o t a v a i l a b l e . However, t h e

Barbee and Wa l k e r, Leeds , M a n h a t t o n , Tecumseh ,S a v a g e , B u c k e y e , K i n n e r , L a s t C h a n c e , M a g g i e ,C a l i f o r n i a , Thompson, and McNally were by f a r th el a r g e s t p r o d u c e r s i n t h e m i n i n g d i s t r i c t . (SeeTable 8 ) .

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MINERAL DEPOSITS

The major ore d e p o s i t s o f th e Har r i sburg ( S i lve r Reef) mining d i s t r i c t occur on th e Buckeye Reefwes t o f Leeds and on t h e White Reef t o t h e w e s t .Less i m p o r t a n t d e p o s i t s occu r s p o r a d i c a l l y on th eBut t e Reef and t h e E a s t Reef from U. S. Highway 91e a s t and sou th a long the S i l v e r Reef sands tone o u tcrops t o th e Virg in River. The ore d e p o s i t s rangedfrom a few f e e t i n d i a m e t e r t o bod ie s s e v e r a l hundred f e e t i n l e n g t h and a hundred f e e t o r more i nw i d t h . In t h i c k n e s s t hey v a r i e d from t h i n p l a t e sof the o re m i n e r a l t o m i n e r a l i z e d zones as much as20 f e e t t h i c k . In p l a n t h e d e p o s i t s were d i s hs h a p e d o r e l o n g a t e l e n s e s , o t h e r s were a l m o s tamoeba- l ike i n shape with f o o t - l i k e p r o j e c t i o n s o f ft h e main body. The g r a d e o f t h e o r e , as w e l l asth e s i z e and shape o f b o d i e s , was s u b j e c t to cons i d e r a b l e v a r i a t i o n s . Zones a s s a y i n g more t h a n$500 t o th e to n were mined l o c a l l y , bu t t he averageg r a d e o f t h e d i s t r i c t p r o b a b l y d i d n o t e x c e e d$20-$25 wor th of s i l v e r t o t h e t o n . Gold was n o tp r e s e n t excep t r a r e l y i n t r a c e s . C e r a r g y r i t e cons t i t u t e d more than 90% of th e ore m i n e r a l s . S i l v e rs u l f i d e ( a r g e n t i t e ? ) was r e p o r t e d , b u t d o u b t l e s splayed a minor p a r t i n th e t o t a l p r o d u c t i o n of th ed i s t r i c t . M a l a c h i t e , a z u r i t e , and minor vanadiumuran ium-bea r ing m i n e r a l s a l s o occu r r ed i n th e d i st r i c t

b u t t h e y were of minor impor t ance and weren o t mined d u r i n g t h e f o r m e r p r o d u c t i v e p e r i o d oft h e camp.

G e n e r a l C h a r a c t e r o f t h e Ore D e p o s i t s

The m a j o r i t y o f t h e o r e d e p o s i t s o c c u r i nd e f i n i t e s t r a t i g r a p h i c zones w i t h i n t h e S i l v e rReef s a n d s t o n e . G e n e r a l l y , most o f t h e d e p o s i t s

were found a t or n e a r the Leeds-Tecumseh sands tonec o n t a c t t hough t h e r e was c o n s i d e r a b l e v a r i a t i o nfrom i t . In a few p l a c e s s i l v e r m i n e r a l i z a t i o nc u t a c r o s s s t r a t i g r a p h i c b o u n d a r i e s and showed nos e l e c t i v i t y f o r one bed over a n o t h e r .

- 78 -



On t h e White R e e f t h e knoyn z o n e s y e r e r es t r i c t e d t o t h e Leeds s a n d s t o n e , y h e r e a s on t h eBuckeye , B u t t e , and E a s t Reef e i t h e r th e Tecumsehor Leeds s a n d s t o n e c o n t a i n e d t h e s i l v e r d e p o s i t s .Loca l accumula t ions o f coppe r c a r b o n a t e s and minor

copper s u l f i d e s yere a lmos t r e s t r i c t e d t o t h e LeedsYhi te sands tone , though r a r e l y malach i t e and a z u r i t eoccupy s m a l l a r e a s i n th e o v e r l y i n g Tecumseh s a n ds t o n e . The uran ium-vanad ium m i n e r a l s o c c u r r e d i nv e r y s m a l l q u a n t i t i e s i n t h e Tecumseh l a v e n d e rs a n d s t o n e and i n l e s s e r amounts i n th e Leeds s a n ds t o n e .

The l a r g e s t o re bod i e s mined o c c u r r e d o ~ t h e

Buckeye R e e f . S e v e r a l o f t h e i n d i v i d u a l b o d i e sy e r e as much as 400 f e e t i n l e n g t h and 200 f e e t i ny i d t h . Most of the bod ies , hoyever, averaged approxi m a t e l y 200-300 f e e t i n l e n g t h and 1 0 0 - 1 5 0 f e e ti n y i d t h . In p l a n v a r i a b l e s h a p e s y e r e t h e r u l e ,mos t o f them b e i n g r o u g h l y e l o n g a t e i n p l a n andl e n s l i k e i n s e c t i o n . Ore b o d i e s y e r e knoyn t o enda b r u p t l y a l o n g an a l m o s t s t r a i g h t l i n e , o t h e r sshoved s m a l l " f i n g e r s " p r o j e c t i n g ou t from t h e mainm i n e r a l i z e d zone . The s t o p e s h a p e s shoyn i n f i gu r e s 1 1 , 1 2 , and 13 i n d i c a t e i n g e n e r a l t h e o rea s s a y c u t - o f f p o s i t i o n o f t h e o r e b o d i e s . Thea c t u a l m i n e r a l i z e d zone m i g h t be much d i f f e r e n ti n a p p e a r a n c e .

The grade of t h e ore v a r i e d from one l o c a l i t yt o a n o t h e r . Some o f t h e r i c h e s t d e p o s i t s y e r emined en Tecumseh H i l l where t h i n p l a t e s of s i l v e rc h l o r i d e p a r a l l e l e d t h e b e d d i n g p l a n e s . C o n t e n to f s i l v e r i n t h e o r e r a n g e d t o $500 o r more p e rt o n , y e t i n a f e y f e e t s u c h h i g h g r a d e s t r e a k syou ld l e n s o u t i n t o a l m o s t b a r r e n r o c k . Sou th ont h e Buckeye R e e f i n t h e K i n n e r and L a s t Chancemines o re b o d i e s as much as 20 f e e t i n t h i c k n e s sye re mined. Here t h e s i l v e r c o n t e n t was more p e rs i s t e n t . S i m i l a r c o n d i t i o n s e x i s t e d on t h e WhiteR e e f i n r e g a r d s t o g r a d e o f o r e body and s i z e .Even a t t h e p r e s e n t t i m e s a m p l e s i n one o f t h e

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mines r anges f rom a few c e n t s i n s i l v e r t o s e v e r a lhundred d o l l a r s t o t h e t o n , b u t t h e s e , of c o u r s e ,a r e s p o t t y o c c u r r e n c e s . Rolke r (p . 26 , 1881) e s -t i m a t e d t h e a v e r a g e g r a d e o f t h e o re t o 1880 a t$20-$25 t o th e t on . La t e r Ba l l (1920) i n a p r i v a t er e p o r t p l a c e d i t n e a r e r t o $15 i n t h e s t o p e s andb e l i e v e d t h a t t h e s o r t i n g o f t h e o re i n t h e minesbrough t t he va lue t o approx imate ly $20 f o r th e m i l lo r e . F o r t h e e n t i r e p e r i o d o f p r o d u c t i o n t h ew r i t e r c o n c u r s w i t h B a l l ' s e s t i m a t e .

The m i n e r a l o g y o f th e o re was ve ry s imple i na l l o f t h e m i n e s . S i l v e r c h l o r i d e ( c e r a r g y r i t e )p r a c t i c a l l y c o n s t i t u t e d th e only ore m i n e r a l . Mala c h i t e and a z u r i t e i n some p l a c e s were d i r e c t l ya s s o c i a t e d with th e s i l v e r mine ra l s b u t mainly werefound s e p a r a t e . The known uranium-vanadium m i n e ra l s are s c a r c e , b u t are a l s o c l o s e l y a s s o c i a t e d i ns t r a t i g r a p h i c p o s i t i o n with th e s i l v e r and copperm i n e r a l s . S i l v e r s u l f i d e was r e p o r t e d as makingup p a r t of t h e o re a t and be low t h e w a t e r t a b l e

d u r i n g t h e mining p e r i o d . I t was commonly a s s o c i -a t e d wi th f o s s i l t r e e s which a l s o c o n t a i n e d c h a l -c o c i t e and p y r i t e .

The i n t i m a t e a s s o c i a t i o n of th e m a j o r s i l v e rm i n e r a l wi th c e r t a i n l i t h o l o g i c t y p e s i s n o t a b l e .With r e f e r e n c e t o a c e r t a i n rock t y p e , t h e o re i sc l a s s i f i e d i n t o f o u r i m p o r t a n t v a r i e t i e s w i t h a

f i f t h l e s s i m p o r t a n t one added :

1 . S m a l l f o s s i l p l a n t and l a r g e r t r e e r e -p l a c e m e n t s by s i l v e r c h l o r i d e i n b u f ft o w h i t e f i n e g r a i n e d s a n d s t o n e . Atd e p t h , t h e s i l v e r s u l f i d e o c c u r s i n t h et r e e r e m a i n s . I r o n o x i d e n o d u l e s ,p s e u d o m o r p h i c a f t e r p y r i t e , and c h a l -c o c i t e n o d u l e s a l s o o c c u r r e d t o g e t h e rw i t h t h e p l a n t r e m a i n s .

2 . D i s s e m i n a t e d s p e c k s o f s i l v e r c h l o r i d ean d t h i n p l a t e s o f t h e same m i n e r a lp a r a l l e l t o t h e b e d d i n g p l a n e s , w i t hr a r e n a t i v e s i l v e r .

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3. S i l v e r c h l o r i d e a s s o c i a t e d w i t h c l a yg a l l an d c l a y b a l l c o n g l o m e r a t e s .

4. S t r e a k s and s m a l l g r a i n s o f s i l v e rc h l o r i d e i n s h e a r e d l a v e n d e r t o b r o w n

i s h r e d s a n d s t o n e .

5 . Horn s i l v e r f i l m s and o c c a s i o n a l l y somen a t i v e s i l v e r on s l i c k e n - s l i d e d s u r f a c e sw i t h i n t h e s h a l e o r " s o a p s t o n e . "

Ore b o d i e s were a l m o s t r e s t r i c t e d t o l e n s e so f l a v e n d e r, and b u f f t o whi te sands tone c o n t a i n i n ga b u n d a n t p l a n t r e m a i n s . The l i t h o l o g y o f t h e s e

o re zones r a p i d l y changed f rom s a n d s t o n e t o c l a ycong lomera t e t o a l t e r n a t i n g s a n d s t o n e and s h a l e s .On th e s t r i k e and d ip such a body t h i n n e d and d i sa p p e a r e d o r became t o o s m a l l t o mine p r o f i t a b l y .Some c a r b o n a c e o u s m a t e r i a l e x t e n d e d b e y o n d t h es i l v e r o re l i m i t . The s i l v e r c o n t e n t w i t h i n t h ec l a y g a l l and c l a y b a l l c o n g l o m e r a t e s b e h a v e d i na l i k e manner.

Though c o m m e r c i a l s i l v e r d e p o s i t s were r es t r i c t e d t o t h e S i l v e r -Reef s a n d s t o n e member o fth e Chin l e f o r m a t i o n , a s s a y s i n d i c a t e t h a t a v e r yminor amount o f s i l v e r i s p r e s e n t i n th e r ocks bo thabove and be low i t . In f a c t , w i t h i n t h e memberi t s e l f , i t would be d i f f i c u l t t o f i n d a s am p l ef r e e o f a t r a c e o f s i l v e r . G o l d , commonly ana s s o c i a t e o f s i l v e r i n many d i s t r i c t s as a t l e a s ta t r a c e , was n o t i n d i c a t e d as be ing p r e s e n t i n th eo r e d e p o s i t s w h i c h were mined d u r i n g t h e e a r l yp e r i o d o f th e camp. However, N e s b i t t c l a i m s t h a t(p . 464, 1902) though t h e o r e s n e v e r showed "anygold by a s s a y, i n l e a c h i n g th e o r e - - s i l v e r s u l f i d e sproduced c o n t a i n e d a t r a c e o f g o l d . " Mr. F. H a r tl e y , f o r m e r owner o f t h e Cobb m i n e , a l s o n o t e d( p e r s o n a l communica t ion) t h a t some g o l d was p a i df o r i n a s h i p m e n t o f s i l v e r o r e f rom t h e m i n e .A. C o l b a t h r e p o r t s :

t h a t i n 1 5 0 s a m p l e s r u n f o r g o l d t h eg r e a t ~ a j o r i t ywere b l a n k s , i n a d d i t i o na few t r a c e s were o b t a i n e d and a 10 f o o t

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sample f rom t h e W a r s a ~i n c l i n e on t h eB u c k e y e R e e f t o t h e e a s t - - c o n t a i n e dgold $2 ( o l d p r i c e ) , s i l v e r e i g h t ouncesand coppe r 0.4% t o t h e t o n .

Samples o f c h a l c o c i t e - p y r i t e c o n c r e t i o n s c o ll e c t e d f rom t h e u n d e r l y i n g F i r e Clay b e n t o n i t i cs h a l e s by t h e ~ r i t e rassayed up t o $4.90 i n go ld ,1.85 ounces i n s i l v e r and 30% of copper t o t he t on .

Since th e v a r i o u s ore d e p o s i t s i n th e d i s t r i c tshow such s i m i l a r h a b i t s o f o c c u r r e n c e , and s i n c et h e y a r e so i n t i m a t e l y r e l a t e d t o t h e e n c l o s i n gs a n d s t o n e b e d s , an o v e r - a l l d e s c r i p t i o n o f t h e

f i e l d o c c u r r e n c e s seems j u s t i f i e d . F or e a s e o fd e s c r i p t i o n and u n d e r s t a n d i n g , t hey a re d i s c u s s e daccord ing t o t h e i r l o c a t i o n on th e fo l l owing r e e f s :

( 1 ) . The White Reef ~ e s t and s o u t h of th eo ld town o f S i l v e r Reef .

( 2 ) . The Buckeye R e e f e a s t and s o u t h oft h e o l d t own and s o u t h o f i t s d i sa p p e a r a n c e n e a r t h e Emily Jane p r o pe r t y .

(3) . The B u t t e R e e f w e s t o f t h e t o ~ n o fL e e d s .

(4). The E a s t R e e f on t h e nose o f t h eV i r g i n a n t i c l i n e and s o u t h t o t h eV i r g i n R i v e r .

White Reef Depos i t s

S i l v e r

Commercial s i l v e r m i n e r a l i z a t i o n i s s p o r a d ic a l l y d i s t r i b u t e d along th e White Reef from a p o i n ts o u t h o f t h e o ld t o ~ n of H a r r i s b u r g t o a p o i n t a

fewh u n d r e d

f e e t n o r t hof

t h eBarbee

and Walkermine where t h e r e e f i s cove red by a l l u v i u m . Theg r e a t e s t s i l v e r c o n c e n t r a t i o n s appear to have t akenp l a c e n e a r t h e Thompson-Cobb a r e a , the Leeds Mineand th e Barbee and Walker mine a r e a . In a l l t h r e eof t h e s e l o c a l i t i e s th e ore d e p o s i t s a re r e s t r i c t e dt o th e Leeds sands tone .

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The i n d i v i d u a l d e p o s i t s w i t h i n t h e s e a r e a sr a n g e d f rom t h i n s i l v e r c h l o r i d e p l a t e s a long t h ebedd ing p l a n e s t o r e p l a c e m e n t s o f p a r t s o f f o s s i lt r e e s . H a r t l ey ( p e r s o n a l communica t ion , Dec. 1948)

n o t e s an i n t e r e s t i n g f e a t u r e of m i n e r a l i z a t i o n n e a rth e f o s s i l t r e e s . He s t a t e s t h a t s p o r a d i c d i s t r ib u t i o n o f s i l v e r would p r o g r e s s i v e l y show h i g h ~ r

s i l v e r c o n t e n t as mine c u t s n e a r e d a t r e e . Veryc l o s e t o th e f o s s i l m a t e r i a l t h e s i l v e r c o n t e n t wasa lways h i g h . H is d e s c r i p t i o n s u g g e s t s an a u r e o l el i k e d i s t r i b u t i o n o f s i l v e r a round t h e s o f t , p a r tl y decomposed f o s s i l .

The l i t h o l o g y o f t h e u n i t s c o n t a i n i n g s i l v e ron t h e Whi te Ree f i s a l s o v a r i a b l e . At t h e S o u t hThompson mine , a w h i t e , f i n e - g r a i n e d s a n d s t o n e w i t h1 / 8 t o 1 / 2 i n c h c l a y g a l l s was mined f o r i t s s i l v e rc o n t e n t . Up d ip 80 f e e t th e bed g r a d e s i n t o a b u f f ,c r o s s - l a m i n a t e d , f i n e - g r a i n e d s a n d s t o n e which i sc l a y a t t h e b a s e . At t h e Cobb m i n e , m i n i n g o p e ra t i o n s were a l m o s t r e s t r i c t e d t o w h i t e s a n d s t o n eb e d s c o n t a i n i n g a b u n d a n t g r e e n t o g r a y c l a y g a l l s

and b a l l s . Some o f t h e b a l l s w e r e a s much a sa

f o o t o r more i n t h i c k n e s s and showed e l o n g a t i o np a r a l l e l t o t h e b e d d i n g . The g a l l s were a s muchas a h a l f i n c h o r more i n l e n g t h . On t h e f o o t w a l l ,s h a l e b e d s l e n s i n and o u t a l o n g t h e s t r i k e . Int h e N i c h o l s Mine , s i l v e r OTe i s r e p o r t e d t o h a v ec o a t e d many o f t h e h i g h l y s l i c k e n s l i d e d f r a c t u r e so f a " s o a p s t o n e " b e d . The h o r i z o n i s a s much a sf o u r f e e t t h i c k and l e n s e s o u t c o m p l e t e l y 60 f e e t

s o u t h of t h e f o u r _ f o o t t h i c k zone . In t h e g e n e r a la r e a o f t h e s e mines t h e main o re h o r i z o n o c c u r r e du n d e r a c a p p i n g o f l a v e n d e r s a n d s t o n e which g r a d e di n t o a y e l l o w - b r o w n s a n d s t o n e and r e d m i c a c e o u ss a n d s t o n e b e l o w.

S i m i l a r o re d e p o s i t s o c c u r a t t h e Leeds minet o t h e n o r t h . H e r e 40 f e e t b e l o w t h e Tecumsehs a n d s t o n e a b u f f , f i n e - g r a i n e d s ands tone w i t h t h i n ,

c r o s s - l a m i n a t i o n s was e x t e n s i v e l y m i n e d . Remark-a b l y e n o u g h , w i t h i n a few f e e t t h e o re bed g r a d e sl a t e r a l l y i n t o a s a n d s t o n e c o n t a i n i n g a b u n d a n tc l a y b a l l s a f o o t o r more i n d i a m e t e r . S t r a t ig r a p h i c a l l y a b o v e , and p o s s i b l y a l o n g t h e s t r i k e

- 83 -



t h e b e d s change t o a l t e r n a t i n g s h a l e and s a n d s t o n eb e d s a b o u t s i x i n c h e s t h i c k . A p p a r e n t l y t h e l a tt e r tw o l i t h o l o g i c u n i t s d i d n o t c o n t a i n muchs i l v e r as t h e y have n o t b e e n m i n e d . As a r e s u l to f t h e d e c o m p o s i t i o n o f f o r m e r p l a n t m a t e r i a l ,n a t u r a l molds have s u p e r i m p o s e d a h i g h d e g r e e ofp o r o s i t y and i n c r e a s e d t h e p e r m e a b i l i t y on t h em a i n o r e h o r i z o n i n t h e m i n e . I r o n o x i d e andc o p p e r c a r b o n a t e s commonly r e p l a c e or s t a i n mucho f t h e f o r m e r p l a n t s u b s t a n c e and mold i n t e r i o r s .

Nor th a t t h e B a r b e e and Walke r mine i n t h eu p p e r s t o p e w a l l s a f i n e l y l a m i n a t e d b u f f t o

w h i t i s h f i n e - g r a i n e d s a n d s t o n e i n p l a c e s f i n e l yc r o s s - l a m i n a t e d o c c u r s a p p r o x i m a t e l y 30 f e e t b elow t h e Tecumseh c o n t a c t .

Copper

M a l a c h i t e and a z u r i t e r e p l a c e m e n t s o f f o s s i lp l a n t m a t e r i a l o c c u r i n some o f t h e m i n e s a l o n gt h e White Reef and a l s o a long i t s e a s t f a c e . Mala c h i t e c o n s t i t u t e s more t h a n 90% o f t h e c o p p e rc a r b o n a t e p r e s e n t . I n e v e r y p l a c e , e x c e p t o n e ,t h e c o p p e r i s d i r e c t l y a s s o c i a t e d w i t h c a r b o n ac e o u s m a t e r i a l . I r o n - o x i d e s t a i n s are a l s o l o c a l l ya b u n d a n t and a s s o c i a t e d w i t h t h e c o p p e r m i n e r a l s .At t h e E m i l y J a n e p r o p e r t y s o u t h of t h e Thompsona d i t , a f o s s i l - p l a n t h o r i z o n o c c u r s as a l e n s moret h a n t h r e e f e e t t h i c k i n b u f f t o l i m o n i t e - b r o w ns a n d s t o n e . The bed r a p i d l y l e n s e s o u t n o r t h and

s o u t h a l o n g t h e s t r i k e . L i m o n i t e p s e u d o m o r p h sa f t e r p y r i t e and a s s o c i a t e d c h a l c o c i t e nodu l e s arer a n d o m l y d i s t r i b u t e d i n t h e s a n d s t o n e and o c c u rw i t h t h e c o p p e r c a r b o n a t e r e p l a c e m e n t s . S m a l ll e n s e s o f b u f f t o w h i t e s a n d s t o n e c o n t a i n i n g copperc a r b o n a t e s n o r t h and s o u t h o f t h e Thompson minea d i t a re exposed a long th e r e e f f a c e . These l e n s e save rage l e s s t h a n t h r e e f e e t i n t h i c k n e s s and t h i nr a p i d l y on t h e s t r i k e , se ldom e x t e n d i n g more t h a n

15 0 t o 300 f e e t . T h e i r e x t e n t on t h e d i p i s no tknown. In t h e Newton Mine a 2 ' - 5 ' bed o f abundan tm a l a c h i t e - a z u r i t e p l a n t r e p l a c e m e n t s i s e x p o s e di n th e sou th d r i f t . I t i s s e p a r a t e d f rom a s i l v e rb e a r i n g zone by a mass ive whi te sands tone t h r e e f e e tt h i c k and a c l a y bed as much as a f o o t t h i c k . Upd i p t h e copper and s i l v e r zones appear t o c o a l e s c e .



A n o t a b l e l e n s o f s a n d s t o n e w i t h c o p p e r - c a rb o n a t e s and i r o n - o x i d e r e p l a c e m e n t s o f f o s s i lp l a n t s c r o p s o u t a t t h e s o u t h en d o f t h e L e e d smine s u r f a c e s t o p e . The l e n s e x t e n d s 1 0 5 0 f e e tsou th a long t h e s t r i k e . The t h i c k n e s s r a n g e s f roma few i n c h e s t o more t h a n t h r e e f e e t . I r o n o x i d er e p l a c e m e n t s o f f o s s i l s a re more a b u n d a n t l o c a l l yt h a n t h e c o p p e r c a r b o n a t e s , b u t i n g e n e r a l t h em a l a c h i t e - a z u r i t e c o m b i n a t i o n i s t h e more common.The s a n d s t o n e c o n t a i n i n g t h e m i n e r a l s i s b u f f ,f i n e - g r a i n e d and i s c u t o f f a g a i n s t a cha n n e l f i l l -

in g of l a v e n d e r Tecumseh s a n d s t o n e .

Other s m a l l showings o f m a l a c h i t e and a z u r i t eoccur no r t h o f th e Leeds mine n e a r th e Hones t Miners h a f t and n o r t h o f t h e B a r b e e and Wa l k e r m i n e .Some p r o s p e c t p i t s and i n c l i n e s have b e e n p u t downon them, b u t t h e i r s u r f a c e e x p r e s s i o n s a r e n o t - a se x t e n s i v e as t h o s e a l r e a d y d e s c r i b e d .

Uranium-Vanadium

No v i s i b l e uran ium o c c u r r e n c e s were n o t e d ont h e Whi te R e e f . However, S t u g a r d ( p . 1 6 , 1950)r e c o r d s a s s a y d a t a on a " s o a p s t o n e " s a m p l e f rom100 f e e t i n s i d e th e Cobb mine . T h i s i s i n d i c a t e da s s a m p l e 2 i n f i g u r e 8 . U r a n i u m c o n t e n t was0 .003 p e r c e n t . S i m i l a r l y a t th e Leeds Mine 0 .005p e r c e n t uran ium c o n t e n t was o b t a i n e d f rom a g rabsample a t th e mine e n t r a n c e . He d o e s n o t m e n t i o nany v i s i b l e u r a n i u m m i n e r a l s i n t h i s a r e a . Bothth e L e e d s and B a r b e e and Wa l k e r t a i l i n g s dumpsf a i l e d t o show any a b n o r m a l g e i g e r c o u n t s .

Buckeye Reef

From d e p o s i t s v e r y s i m i l a r t o t h o s e on t h eWhite R e e f , t h e Buckeye R e e f p r o d u c e d 75 p e r c e n tor more of the s i l v e r mined i n th e d i s t r i c t . Copperc a r b o n a t e s a r e a s s o c i a t e d w i t h and a r e s e p a r a t ef rom t h e s i l v e r o c c u r r e n c e s , b u t t h e s e a r e l e s sa b u n d a n t t h a n on t h e Whi te R e e f .

S i l v e r

The c h a r a c t e r and o c c u r r e n c e o f t h e s i l v e rd e p o s i t s i s a l m o s t i d e n t i c a l w i t h t h o s e a l r e a d yd e s c r i b e d w i t h b u t two e x c e p t i o n s .

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1 . S i l v e r o c c u r r e d i n a s h e a r e d s a n d s t o n ec u t t i n g more t h an one s t r a t i g r a p h i c u n i t ,and

2 . S i l v e r o r e s o c c u r r e d i n bo th t h e Tecum-seh and Leeds s a n d s t o n e r a t h e r t han th eLeeds a l o n e .

The v a r i a b i l i t y i n t h e s t r a t i g r a p h i c p o s i t i o n s oft h e o r e d e p o s i t s w i t h i n t h e r e e f ; t h e i r w i d t h ,l e n g t h , and t h i c k n e s s so c h a r a c t e r i s t i c o f t h eWhite Reef d e p o s i t s a l s o a p p l i e s t o t h e s e d e p o s i t s .

The o re c o n s i s t e d o f : sma l l g r a i n s of s i l v e rc h l o r i d e d i s s e m i n a t e d th rough c e r t a i n zones i n th es a n d s t o n e , r e p l a c e m e n t s o f f o r m e r r e e d - l i k e andr u s h - l i k e f o s s i l s , p a r t s o f t r e e s , f i l l i n g s i ns h e a r z o n e s , t h i n p l a t e s o f s i l v e r - c h l o r i d e a longb e d d i n g p l a n e s and o c c a s i o n a l l y as an a s s o c i a t eo f c l a y g a l l s i n s a n d s t o n e . The m a j o r i t y o f t h ed e p o s i t s , h o w e v e r, were a s s o c i a t e d wi th p l a n t r em a i n s . H o w e v e r, R o l k e r ( p . 2 5 - 2 7 , 1881) n o t e dt h a t t h e :

s o u t h e r n and m i d d l e p o r t i o n s o f t h eBuckeye R e e f show l e s s f r e q u e n t l y v e g -e t a b l e r e m a i n s t h a n t h e r e m a i n i n g p o rt i o n o f th e White Reef and i n p a r t t h e s er emains a re a b s e n t . We f i n d i n th e same

l i n e o f b e d d i n g s t r a t a h o l d p e t r i f i c at i o n s f rom s i x i n c h e s t o t h r e e f e e tt h i c k ( t h e beds ) which c o n t a i n no s i l -

v e r o r e , w h i l e above and be low i t s i l -

v e r i s f ound i n good p e r m a n e n t g r a d e si n s t r a t a s h o w i n g a s c a r c i t y o f v e g et a b l e r e m a i n s . A g a i n , I have s e e n a

s t r a t u m w h e r e t h e u p p e r tw o f e e t a ss a y e d a b o u t $ 3 0 , t h e n s i x i n c h e s a s

s a y i n g $ 1 0 0 o r m o r e , t h e n 15 i n c h e sb a r r e n , and b e l o w i t a l a y e r o f $20r o c k , a l l o f t h e s t r a t a b e i n g f u l l o fp e t r i f i c a t i o n s .

The s i l v e r - b e a r i n g s a n d s t o n e l e n s e s t h i n n e dand t h i c k e n e d w i t h i n s h o r t d i s t a n c e s a l o n g t h e



s t r i k e o f th e R e e f . Two p r o d u c i n g h o r i z o n s , s e pa r a t e d by 15 o r more f e e t o f b a r r e n s a n d s t o n e , i nsome p l a c e s c o n v e rg e d i n a s h o r t d i s t a n c e on t h es t r i k e o r d ip and formed a s i n g l e l e n s . The t h i c kn e s s o f t h e i n d i v i d u a l z o n e s r a n g e d f rom a fewi n c h e s , a s on Tecumseh H i l l , t o s e v e r a l f e e t asi n th e Buckeye Mine. Some zones c o n t a i n e d phenome n a l l y r i c h p l a t e s o f s i l v e r - c h l o r i d e i n s a n d s t o n eo n l y a few i n c h e s t h i c k , t h o u g h a b o v e and b e l o wt h e s e , t h e s i l v e r c o n t e n t may h a v e b e e n v e r y lowor a b s e n t . In a number o f p l a c e s a t h i n h o r i z o nw i t h a h i g h s i l v e r c o n t e n t p e r m i t t e d t h e m i n i n ga t a p r o f i t o f s e v e r a l f e e t a b o v e o r b e l o w, o r

b o t h , of s u b - m a rg i n a l o re . Thus , many o f th e p r es e n t s t o p e f a c e s do n o t r e f l e c t th e o r i g i n a l t h i c k -n e s s o f th e h i g h l y m i n e r a l i z e d h o r i z o n s .

In g e n e r a l , th e ore d e p o s i t s were c o n f o r m a b l et o t h e b e d d i n g , t h o u g h a g r a d u a l f a d i n g o u t o fm e t a l c o n t e n t w i t h i n a c e r t a i n bed o c c u r r e d i n a

number o f p l a c e s . Many s m a l l s l i p s f i l l e d w i t hc l a y c o n t a i n e d s i l v e r . As R o l k e r p o i n t e d o u t f o r

t h e Buckeye mine (p . 29 , 1881)a

" t h r o w i n g of t h eore above o r be low" m i g h t o c c u r , or t h e o re wouldq u i c k l y end beyond th e s l i p . He a l s o no ted (p . 2 5 -26, 1 8 8 1 ) :

t h a t an a r g i l l a c e o u s s a n d s t o n e t e ni n c h e s t o two f e e t t h i c k may be p r e s e n tb e l o w t h e s i l v e r p r o d u c i n g b e d s w h i c ho f t e n c a r r i e d much s i l v e r an d f r e -

q u e n t l y s h o w e d s o l i d s h e e t s o f h o r ns i l v e r a l o n g t h e s e a m s o f t h e t h i c kn e s s o f a k n i f e b l a d e .

These s i l v e r o c c u r r e n c e s , as he a p t l y a d d s ,were n o t u n i v e r s a l l y p r e s e n t t h r o u g h o u t t h e d i st r i c t . Many o f t h e open s t o p e s on t h e B u c k e y eReef show a f o o t w a l l o f w h i t e t o b u f f s a n d s t o n ewhich has been swep t p e r f e c t l y c l e a n . A p p a r e n t l y

much o f t h e s i l v e r was c o n c e n t r a t e d i n t h e f i n e s .The f o o t w a l l s a n d s t o n e shows abundan t i m p r e s s i o n so f c l a y g a l l s and f o s s i l p l a n t s , some p a r t i a l l yr e p l a c e d by c o p p e r c a r b o n a t e . Newman ( P e r s o n a lC o m m u n i c a t i o n , May, 1 9 4 8 ) o b s e r v e d t h a t i n t h e

- 87 -



S a v a g e mine w o r k i n g s a " r e d d i s h m i c a c e o u s s a n ds t o n e i s p r e s e n t above th e o r e - b e a r i n g w h i t e s a n ds t o n e . " R o l k e r r e c o r d s ( p . 25 , 1881) a s i m i l a r

o b s e r v a t i o n f o r t h e m i n e s n e a r b y .

At t h e s o u t h end o f t h e Buckeye R e e f s i l v e ro r e was mined f rom b o t h t h e Te c u m s e h and L e e d ss a n d s t o n e b e d s an d t h e i r c o n t a c t n o r t h o f t h eS t o r m o n t mine was e x t e n s i v e l y p r o s p e c t e d . Neart h e g ap l e a d i n g t o t h e f a rm l a n d , s o u t h o f t h eC a l i f o r n i a m i n e , s e v e r a l i n c l i n e s open i n t o caveds t o p e s i n f i n e t o medium-g ra ined , l a v e n d e r , f i n e l y

l a m i n a t e d and somewhat s h e a r e d s a n d s t o n e . At t h eC a l i f o r n i a mine s i l v e r o re was mined f rom a t l e a s ttw o h o r i z o n s , one w i t h i n t h e Tecumseh s a n d s t o n ea p p r o x i m a t e l y 1 0 - 1 4 f e e t f rom i t s c o n t a c t w i t h t h eo v e r l y i n g D u f f i n s a n d s t o n e and t h e o t h e r a t t h ec o n t a c t of th e Leeds and Tecumseh i n a p l a t y l a v e nd e r s a n d s t o n e . Thi s same o re zone e x t e n d e d n o r t hward i n t o t h e M a g g i e - L a s t Chance m i n e s . A s t e e pf l e x u r e e a s t o f t h e C a l i f o r n i a s h a f t i n t h e n e a rs u r f a c e s t o p e s u g g e s t s t h a t m i n e r a l i z a t i o n wasl o c a l i z e d a l o n g t h i s s h e a r e d and f o l d e d z o n e .

F i v e h u n d r e d f e e t s o u t h e a s t o f t h e S a v a g es h a f t s i l v e r m i n e r a l i z a t i o n o c c u r r e d i n a s h e a r e d ,b r o w n i s h t o l a v e n d e r s a n d s t o n e i n a zone 40 f e e twide and 300 f e e t l ong . ( P l a t e V I I I ) . This may w e l lb e t h e f a u l t e d n o r t h w a r d e x t e n s i o n o f t h e s h e a rzone o f t h e C a l i f o r n i a mine . At t h e Buckeye minej u s t n o r t h o f t h e S a v a g e s h a f t , o re b o d i e s weref rom 18 i n c h e s t o a l m o s t 20 f e e t t h i c k . S m a l lb r e a k s c a u s e d t h e o r e t o jump 2 - 6 f e e t i n o v e rl y i n g or u n d e r l y i n g b e d s . Both t h e B u ckeye anda d j a c e n t Kinne r o r e h o r i z o n s were n e a r th e c o n t a c to f t h e Tecumseh and Leeds s a n d s t o n e s .

On Te c u m s e h H i l l t h e o r e o c c u r r e d i n t h e

Tecumseh s a n d s t o n e and a l s o a t th e c o n t a c t of th eTecumseh and u n d e r l y i n g Leeds s a n d s t o n e . The opens t o p e s show w a l l s o f f i n e l y l a m i n a t e d , l a v e n d e rt o g r a y s a n d s t o n e . M o s t o f t h e o r e b o d i e s onTecumseh H i l l were h i g h g r a d e , t h i n s a n d s t o n e bedsr a n g i n g f rom t e n i n c h e s t o p o s s i b l y t h r e e f e e t i nt h i c k n e s s . The i n d i v i d u a l o re d e p o s i t s were s m a l l



and n e a r th e s u r f a c e . Hunt ley (p . 480, 1881) r ec o r d s t h a t on t h e M a n h a t t a n , S i l v e r F l a t andTe c u m s e h p r o p e r t i e s :

o r e was f ound h e r e f rom 4 - 1 5 f e e t b elo w t h e g r a s s i n c o m p a r a t i v e l y s m a l lb o d i e s f r om 1 - 3 f e e t t h i c k and 40 t o50 f e e t wide and l o n g . S e v e r a l f a u l t so f 4-6 f e e t and w a v e - l i k e f o r m a t i o n sw e r e n o t i c e d by P r o f e s s o r Maynard i nsummer o f 1 8 8 0 .

C o p p e r

Copper c a r b o n a t e o c c u r r e n c e s on t h e BuckeyeR e e f a r e n o t so p r o m i n e n t as t h o s e on t h e Whi teReef . Some showings , however, a r e abundan t i n t h eBuckeye Reef 500 f e e t sou th of th e gap i n th e Leedss a n d s t o n e . Here m a l a c h i t e and m i n o r a z u r i t e w i t hl i m o n i t e nodu l e s r e p l a c e f o s s i l p l a n t s . The zoner a n g e s t o a s much as 2 1 / 2 f e e t i n t h i c k n e s s ande x t e n d s o v e r 120 f e e t a l o n g t h e s t r i k e . On t h ed i p s l o p e e a s t o f t h e l a r g e C a l i f o r n i a mine dump

a deep -g ree n m a l a c h i t e occurs as g r a i n - l i k e massesand c o a t i n g s o f q u a r t z g r a i n s i n a f i n e - g r a i n e d ,w h i t e s a n d s t o n e . However, s m a l l , p a r t l y r e p l a c e dp l a n t i m p r e s s i o n s o ccu r a l ong t h e b e d d i n g p l a n e swi th in an inch of th e malach i t e i n a lmos t a l l c a s e s .On t h e f a c e o f t h e r e e f t o t h e e a s t , a somewhatshea r ed w h i t e s a n d s t o n e i s s t a i n e d wi th m a l a c h i t eo v e r a t h i c k n e s s o f t h r e e f e e t . Below i t , i n ab u f f , f i n e - g r a i n e d s a n d s t o n e , c o p p e r c a r b o n a t e

r e p l a c e s p l a n t f o s s i l s o v e r a s t r i k e d i s t a n c e o f50-80 f e e t . Below t h i s h o r i z o n and t o t h e s o u t ho t h e r t h i n , w h i t e t o b u f f s a n d s t o n e b e d s c o n t a i nminor m a l a c h i t e s t a i n s . J u s t n o r t h o f t h e s m a l lt h r u s t on t h e f a c e o f t h e Buckeye R e e f , a 1 t o 2f o o t l e n s o f b u f f , f i n e - g r a i n e d s a n d s t o n e 60 f e e tl o n g shows prominen t malach i t e p l a n t r e p l a c e m e n t s .Nor th a l o n g t h e r e e f f a c e o t h e r s m a l l s a n d s t o n ebeds c o n t a i n i n g m a l a c h i t e s t a i n s on p l a n t f o s s i l s

and g e n e r a l l y l e s s t h a n t h r e e f e e t t h i c k , e x t e n ds h o r t d i s t a n c e s a l o n g t h e s t r i k e .

The most i m p o r t a n t c o p p e r c a r b o n a t e d e p o s i t sa re a p p r o x i m a t e l y 1000 f e e t e a s t o f F i r e Clay H i l l

- 89 -

,

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RELATIVE AMOUNTS OF COPPER PRESENT

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Zo~I / )ozctI / )

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4II I

F i g u r e 5. R e l a t i v e amounts o f c o p p e r and s i l v e r

t o c a r b o n a t e c o n t e n t o f S i l v e r Reef s a n d s t o n e .



Silver

F i g u r e 6. R e l a t i v e c o p p e r s i l v e r r a t i o s ,Whi te and Buckeye R e e f s .

- 91 -



on t he f ace o f th e Buckeye Reef . Here th e beds a reas much as 2 f e e t t h i c k and ex tend 70 or more f e e ta long th e s t r i k e . A s h o r t d i s t a n c e eas tward a l e n sove r 260 f e e t i n l e n g t h i s conformable t o th e b e dd i n g . The m a l a c h i t e and minor a z u r i t e occu r i n a

p o r o u s , i r o n - o x i d e s t a i n e d , f i n e - g r a i n e d sands tonef i v e f e e t be low t h e Tecumseh s a n d s t o n e c o n t a c t .L o c a l l y , t h e s a n d s t o n e bed t h i c k e n s t o 12 f e e t ,b u t c o p p e r c a r b o n a t e r e p l a c e m e n t s a re found on lyi n p a r t s o f i t . The bed c o n t a i n i n g t h e c o p p e rl e n s e s ou t e a s t w a r d a long th e s t r i k e . One-hundredf e e t e a s t i t a p p e a r s a g a i n f o r 60 f e e t and i s asmuch as one f o o t i n t h i c k n e s s . The bed shows malac h i t e rep lacements of f o s s i l p l a n t s . Near the s h o r ta d i t wes t of th e Leeds R e s e r v o i r , m a l a c h i t e s t a i n sa s s o c i a t e d wi th c a r n o t i t e and v o l b o r t h i t e (? ) ~ c u r

i n s h e a r e d , b u f f , f i n e - g r a i n e d s a n d s t o n e .

Uran ium-Vanad ium

Uranium b e a r i n g m i n e r a l s occur on th e BuckeyeR e e f a t v a r i o u s p l a c e s , b u t i n minor q u a n t i t i e s .O c c u r r e n c e s o f c a r n o t i t e h a v e b e e n n o t e d on t h ee a s t s i d e o f Tecumseh H i l l , j u s t e a s t of th e SavageS h a f t , on th e Doyle s h a f t dump, i n two sma l l s h a f t s300 f e e t t o t h e e a s t , and i n s e v e r a l p r o s p e c t p i t ss o u t h and e a s t o f t h e Doyle s h a f t . E x p l o r a t i o nwork u n d e r t a k e n on s e v e r a l o f t h e s e o c c u r r e n c e sa f t e r th e f i e l d work f o r t h i s r e p o r t had been comp l e t e d exposed more o f t h e d e t a i l s of t h e o c c u rr e n c e s . S t u g a r d (1951) summarizes t h e s e . On th e

e n l a rg e m e n t s o f maps from P r o c t o r ' s o r i g i n a l r ep o r t ( P r o c t o r , 1 9 4 9 ) , he has shown th e a r e a l d i st r i b u t i o n and p o s i t i o n o f t h e uran ium o re zoneson t h e Buckeye R e e f .

Three o re zones a r e r e c o r d e d . On TecumsehH i l l th e i n f e r r e d p o s i t i o n of th e uranium m i n e r a li z a t i o n l i e s a p p r o x i m a t e l y 10 f e e t above th e c o nt a c t o f th e Leeds s a n d s t o n e i n th e Tecumseh s a n ds t o n e . Sou th of t h e Doyle s h a f t two uran ium orezones a re known. S t u g a r d (1951) names t h e s e th eu p p e r and l ower o r e zones . The lower l i e s app roxi m a t e l y 33 f e e t above th e Tecumseh-Leeds sands tonec o n t a c t , and t h e uppe r o r e zone i s 15 f e e t h i g h e rs t r a t i g r a p h i c a l l y . The u p p e r zone i s exposed i n

- 92 -



s e v e r a l p i t s i n th e d ip s l o p e o f th e Buckeye R e e fn e a r th e Doyle s h a f t . Showings o f c a r n o t i t e andr e l a t i v e l y h i g h G e i g e r - M u e l l e r c o u n t e r r e a d i n g swere no ted by th e au tho r and S t u g a r d app rox ima te ly800 f e e t n o r t h e a s t o f th e Leeds r e s e r v o i r on t h e

c l i f f f a c e o f th e Buckeye R e e f .

Samples 1 2 , 17 , 1 8 , 2 3 , 27, 30 , 36 , 37 and 38( f i g u r e 8) were t a k e n from W i l l i s ' e x p l o r a t i o n p i t375 f e e t sou th and s l i g h t l y e a s t of th e Doyle s h a f t .Samples 16 , 20, 28, 33 , 34 and 35 ( f i g u r e 8) wereo b t a i n e d 750 f e e t e a s t and s l i g h t l y s o u t h of th eDoyle s h a f t on t h e f a c e and s l o p e o f t h e BuckeyeReef . Stugard c o l l e c t e d samples from th e Tecumsehmine dump. These a re r e p r e s e n t e d by samples 5 , 11and 15 i n f i g u r e 8 . In a v e r t i c a l d iamond d r i l lh o l e (Eh rho r n N o . 1 ) s o u t h o f th e Tecumseh m i n e ,and weigh ted average of vanadium f o r 12 f e e t (from1 7 0 - 1 8 2 . 5 f e e t ) was 0 . 1 2 p e r c e n t . No u r a n i u mc o n t e n t was r e c o r d e d f o r t h i s d e p t h . In a d d i t i o nStuga rd c o l l e c t e d 25 grab samples from th e C h r i s t yt a i l i n g dump. A composi te a n a l y s i s o f t h e s e showed0 .010 percen t uranium and 0 .07 p e r c e n t V205 c o n t e n t .A ~ n o t e d i n f i g u r e S, t h e s e t a i l i n g s r e p r e s e n tth e ore s from a t l e a s t s i x mines f rom t h e BuckeyeR e e f , and p o s s i b l y o t h e r s s i n c e cus tom o re wasaccep t ed by th e m i l l . Samples 13 and 14 were c o ll e c t e d from th e Doyle s h a f t dump and probab ly r e p r es e n t t h e p r o j e c t i o n of e i t h e r th e u p p e r o r l o w e ro re zone i n t o th e Doyle s h a f t underg round work ings .

S t u g a r d ' s comments (1951) on th e r e c e n t l y e x -posed ore showings of uranium d e s c r i b e i n some d et a i l th e s i z e and d i s t r i b u t i o n o f th e l a r g e s t knownoccur rences i n th e S i l v e r Reef a r e a :

The l a r g e s t uranium ore d e p o s i t s known . . .a r e i n t h e Tecumseh s a n d s t o n e on Pump-k i n P o i n t (h i l l s l o p e s o u t h and e a s to f Doyle s h a f t ) . Two u r a n i f e r o u s z o n e s ,t h e u p p e r and l o w e r o re z o n e s , a r e e xp o s e d . The l a r g e s t i n d i v i d u a l d e p o s i t ,i n t h e l o w e r o re zone , i s more t h a n 1 . 8f e e t t h i c k ( l o w er c o n t a c t c o n c e a l e d ) and16 f e e t l o n g - w i t h d i s c o n t i n u o u s e x -

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Copper

Co p p e r c a r b o n a t e m i n e r a l s a s s o c i a t e d w i t hp l a n t r e m a i n s a re l o c a l l y a b u n d a n t a l o n g t h e e a s tand wes t s i d e of th e B u t t e Reef i n w h i t e s a n d s t o n e ,b u t none o f t h e l e n s e s a re more t h a n tw o t o t h r e ef e e t t h i c k and ex t end only a few t e n s o f f e e t a longt h e s t r i k e . I n a c c e s s i b l e mine work ings a t a n o t h e r

l o c a l i t y on t h e n o r t h end o f t h e B u t t e R e e f d i dn o t a l low an e x a m i n a t i o n of t h e o re h o r i z o n s t h e r e .

Uranium-Vanadium

Minor showings o f u r a n i u m - v a n a d i u m m i n e r a l iz a t i o n were n o t e d i n a p i t n e a r t h e c o n t a c t o f t h eTecumseh and o v e r l y i n g D u f f i n s a n d s t o n e on t h en o r t h s l o p e o f t h e B u t t e R e e f . S t u g a r d ( 1 9 5 1 )c o l l e c t e d s a m p l e s f rom t h e s e w o r k i n g s . Uraniumc o n t e n t r anged from 0 . 0 3 9 p e r c e n t t o 0 . 2 3 p e r c e n t .No o t h e r o c c u r r e n c e s o f i m p o r t a n c e a r e known f o rt h e B u t t e Reef a r e a .

E a s t Reef

S i l v e r

Geo l o g i c c o n d i t i o n s on t h e E a s t R e e f a r e v e r ys i m i l a r t o t h o s e o f t h e o t h e r t h r e e r e e f s . Them a j o r i t y o f t h e s i l v e r d e p o s i t s l i e a t o r n e a rt h e c o n t a c t o f t h e Tecumseh and Leeds s a n d s t o n e s .Two o t h e r o re h o r i z o n s o c c u r ; one a t t h e D u f f i nMine i n t h e Tecumseh s a n d s t o n e 20 f e e t above t h eL e e d s s a n d s t o n e , and a n o t h e r on t h e Maud c l a i m2700 f e e t s o u t h o f t h e D u f f i n Mine and 25 f e e tb e l o w t h e Te c u m s e h .

On th e r e e f sou th of th e D u ff i n mine p rominen tm a l a c h i t e w i t h m i n o r a z u r i t e and some s i l v e r r ep l a c e and s t a i n p l a n t f o s s i l s . H e r e , a l e n s ofs a n d s t o n e as much as s i x f e e t i n t h i c k n e s s i n c l u d e sp l a n t f o s s i l s r e p l a c e d by m a l a c h i t e . The l e n st h i n s t o a few i n c h e s b o t h n o r t h and s o u t h i n a pp r o x i m a t e l y 300 f e e t . S i m i l a r l e n s e s i n t h e Leedss a n d s t o n e , t hough s m a l l e r i n s i z e , c r o p o u t s o u t h

a long t h e r e e f t o t h e Vi r g i n R i v e r .I m p r e g n a t i o n s o f c a r n o t i t e and p r o b a b l e

a u t u n i t e o c c u r l o c a l l y i n t h e Tecumseh s a n d s t o n ea t t h e D u f f i n and To q u e r v i l l e m i n e s . O t h e r o c c u r -

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r e n c e s a re p r e s e n t on th e nose o f t h e Vi rg i n a n t ic l i n e i n t h e Tecumseh s a n d s t o n e . M a l a c h i t e andc a r n o t i t e p a r t l y r e p l a c e p l a n t r e m a i n s i n a b u f f ,f i n e - g r a i n e d s a n d s t o n e . Some f a i r s h o w i n g s o f

c a r n o t i t e , andm a l a c h i t e r e p l a c i n g

and s t a i n i n gp l a n t f o s s i l s o c c u r a p p r o x i m a t e l y a t h o u s a n d f e e te a s t o f t h e a x i s of t h e Vi rg i n a n t i c l i n e i n a l e n so f b u f f t o g r a y i s h s a n d s t o n e s i x i n c h e s t o 2 1 / 2f e e t t h i c k and s i x f e e t be low a p l a t y l a v e n d e rsands tone ( p l a t e I ) . Minor amounts o f th e uran iumvanad ium m i n e r a l s o c c u r b e l o w t h e l e n s on j o i n tf a c e s . The s a n d s t o n e t h i n s and t h i c k e n s a l o n gt h e s t r i k e . eve r a d i s t a n c e of 300-400 f e e t s e v e r

a l p r o s p e c t a d i t s have been d r i v e n i n t o t h e c l i f ff a c e t o p r o s p e c t t h e s e showings . To th e e a s t a longt h e e r o d e d f a c e s o f t h e d i f f e r e n t f a u l t b l o c k s o fS i l v e r Reef s a n d s t o n e , many p r o s p e c t p i t s have beendug on s i m i l a r showings o f c a r n o t i t e . The m a j o r i t yo f t h e s e , h o w e v e r, a r e a few i n c h e s i n t h i c k n e s s ,and a few f e e t i n l e n g t h .

S t r u c t u r a l R e l a t i o n s h i p s of M i n e r a l i z a t i o n

Channe l S t r u c t u r e s

I t h as been shown t h a t T r i a s s i c s t r e a m s whichd e p o s i t e d t h e S i l v e r Ree f s a n d s t o n e m a i n t a i n e d ar a t h e r c o n s t a n t . d i r e c t i o n o f f l o w i n t h e m i n i n ga r e a p r o p e r . Both th e Tecumseh and Leeds s a n d s t o n ed e p o s i t e d by t h e s e s t r e a m s o c c u r as a s e r i e s o fi n t e r f i n g e r i n g s a n d s t o n e and m i n o r s h a l e l e n s e s .

Many o f t h e s e c h a n n e l f i l l ings c o n t a i n f o s s i lp l a n t m a t e r i a l , d i s t r i b u t e d t h r o u g h o u t t h e i r w i d t h s .I n t h e S o u t h Thompson M i n e , L e e d s M i n e , and i no t h e r s on t h e B u c k e y e R e e f , s i l v e r c h l o r i d e andc o p p e r c a r b o n a t e s r e p l a c e d th e f o s s i l s and s t a i n e dthem t o form t h e commerc i a l o re d e p o s i t s . O t h e rc h a n n e l s f i l l e d w i t h f i n e t o m e d i u m - g r a i n e d s a n ds t o n e w i t h i n c l u d e d c l a y g a l l s and b a l l s l o c a l l yc o n t a i n e d r i c h s i l v e r d e p o s i t s . Copper c a r b o n a t e s

i n q u a n t i t y h a v e n o t b e e n found a s s o c i a t e d w i t ht h i s t y p e o f c h a n n e l f i l l .

The Cobb Mine e x e m p l i f i e s t h e s i l v e r c l a yg a l l - b a l l t y p e . A c o m b i n a t i o n o f t h i s and t h ef o s s i l p l a n t v a r i e t y o c c u r s a t d i f f e r e n t p l a c e s

96



i n th e a r e a . Some o f th e mines a t t h e c o n t a c t o fth e Tecumseh and Leeds s a n d s t o n e on Tecumseh H i l ls u g g e s t t h i s t y p e o f d e p o s i t , a s do p a r t s o f t h eS o u t h Thompson mine a r e a , t h e f a c e o f t h e W h i t e

Reef to th e e a s t , andsome

p r o s p e c t p i t s j u s t sou tho f t h e fa rm l a n d g ap on t h e B u c k e y e R e e f . Thes i l v e r m i n e r a l i z a t i o n i s r e l a t e d t o t h e s e c h a n n e lf i l l s , and even more c l o s e l y t o th e i n c l u d e d f o s s i lp l a n t s and l e s s so t o t h e c l a y g a l l - b a l l cong lomera t e zones w i t h i n th e c h a n n e l s . The d e p o s i t s a r ec l o s e l y r e l a t e d t o t h e t h i c k e r p o r t i o n s , b u t evenh e r e may be v e r y s p o r a d i c . Not a l l c h a n n e l sh o w e v e r, c o n t a i n c o m m e r c i a l q u a n t i t i e s o f s i l -

v e r , a s o n l y a few i n r e s t r i c t e d z o n e s , andm a i n l y n e a r o r a t t h e Te c u m s e h - L e e d s s a n d s t o n ec o n t a c t , appear to have ac t ed as l o c i o f d e p o s i t i o nf o r t h e o r e m i n e r a l s . An i m p o r t a n t s e c o n d a r yf e a t u r e o f th e c h a n n e l s which r e s u l t e d f rom t h edecompos i t ion of th e fo rmer p l a n t s u b s t a n c e i s a l s oi m p o r t a n t . These n a t u r a l molds w i t h c a r b o n f i l m son t h e i r s u r f a c e h a v e y i e l d e d h i g h g r a d e s i l v e ro re i n t h e p a s t .

The c o p p e r c a r b o n a t e m i n e r a l s a r e l i m i t e d ,however, t o th e l e n s e s of c h a n n e l f i l l s c o n t a i n i n gp l a n t - l i k e r e m a i n s . The l e n s o f s a n d s t o n e on t h eEmily J a n e p r o p e r t y on th e f a c e o f th e White Reefi s e s p e c i a l l y n o t a b l e i n t h i s r e s p e c t , a s a r e a l s oth e l a r g e l e n s e s e a s t o f F i r e Clay H i l l and t h o s eon t h e E a s t R e e f s o u t h o f t h e D u f f i n M i n e .

F o l d s

Many g e o l o g i s t s who h a v e v i s i t e d t h e m i n i n gd i s t r i c t have s u g g e s t e d t h a t a g e n e t i c r e l a t i o ns h i p e x i s t s be tw e en t h e Vi r g i n a n t i c l i n e and t h es i l v e r m i n e r a l i z a t i o n . Though R o l k e r m e n t i o n st h e " h o r s e s h o e " ( a n t i c l i n e ) o f t h e Buckeye R e e f ,he does n o t r e l a t e m i n e r a l i z a t i o n s t o i t . B u t l e r(p . 1 5 4 , 1920) observed a p o s s i b l e c o r r e l a t i o n b etween ore l o c a l i z a t i o n and t h e f o l d i n g . B a l l (1920)a p p a r e n t l y was q u i t e c o n v i n ced o f a d i r e c t c o r r espondence f o r he no ted : " t h e d i s t r i b u t i o n ( o f th em i n e r a l d e p o s i t s on t h e a n t i c l i n e ) a p p e a r s t o bemore t h a n a c c i d e n t a l and i n f a c t c a u s a l . " Both

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B u t l e r and B a l l observed t h a t a d i m i n i s h i n g numbero f s i l v e r d e p o s i t s o c c u r s o u t h a l o n g t h e s t r i k eo f t h e Whi te R ee f and s u g g e s t e d t h a t th e g r e a t e r

d i s t a n c e f rom t h e c r e s t o f t h e f o l d m i g h t be th er e a s o n f o r t h e d e c r e a s e i n number.

More d e t a i l e d geo log i c mapping o f th e d e p o s i t si n d i c a t e s t h a t th e main d e p o s i t s a re more c l o s e l ya s s o c i a t e d w i t h t h e a x i s and wes t l imb o f a s u b -s i d i a r y f o l d o f t h e Vi r g i n a n t i c l i n e , i . e . , t h eLeeds a n t i c l i n e o f t h i s r e p o r t . The s i l v e r c o n t e n twas h i g h on b o t h t h e nose o f t h e f o l d and on t h e

w e s t l i m b , y e t th e e a s t l i m b of th e same f o l d con -t a i n s only s p a r s e s i l v e r . The pre sence o f a t h r u s tf a u l t b e t w e e n t h e Buckeye and Whi te Reef f u r t h e rc o m p l i c a t e s t h e s i m p l e r e l a t i o n s h i p o f f e r e d byB a l l and by B u t l e r .

The B u t t e R e e f , a f a u l t e d segment of th e S i l -v e r Reef s a n d s t o n e , i s n e a r e s t t h e c r e s t o f t h el a r g e Vi rg i n a n t i c l i n e , y e t only s p o r a d i c m i n e r a l -i z a t i o n o c c u r s i n t h e s a n d s t o n e . E a s t o f U. S.Highway 9 1 , on t h e n o s e and c r e s t o f t h e V i ~ g i n

a n t i c l i n e , s i l v e r o c c u r r e n c e s i n th e S i l v e r Reefs a n d s t o n e a r e s p o t t y and no m i n e s were d e v e l o p e di n t h i s a r e a . F i n a l l y , s i l v e r o c c u r r e n c e s 16 mi le ss o u t h w e s t n e a r S a n t a C l a r a , i n th e same s a n d s t o n ea p p a r e n t l y , h a v e no d i r e c t r e l a t i o n s h i p t o t h ec r e s t o f a f o l d . Though an i n d i r e c t r e l a t i o n s h i pt o t h e f o l d i n g

maybe i n t e r p r e t e d f rom

th eo c c u r -

r e n c e o f s i l v e r on th e nose of th e Leeds a n t i c l i n e ,o t h e r d e p o s i t s c o n s i d e r a b l e d i s t a n c e s f rom t h ec r e s t o f t h e f o l d would i n d i c a t e t h a t f o l d s weren o t i m p o r t a n t i n l o c a l i z i n g t h e o r e .

J o i n t s

R o l k e r (p . 2 9 , 1881) p o i n t e d ou t t h a t j o i n t si n t h e s a n d s t o n e s of t h e Buckeye and K i n n e r Minesc a u s e d t h e o re t o jump f rom one bed t o a n o t h e r .I n some p laces s i l v e r m i n e r a l i z a t i o n s topped a g a i n s tthem o r was g r e a t l y d i m i n i s h e d on t h e e t h e r s i d aOne i n f e r s f rom h i s r e p o r t t h a t on ly j o i n t s c o n -t a i n i n g c l a y f i l l a f f e c t e d o r e i n t h a t m a n n e r.He a l s o no ted t h a t some o f th e c l a y f i l l i n g i n th e

98



j o i n t s c o n t a i n e d s i l v e r . However, h i s b r i e f n o t ewould s u g g e s t m i n o r i m p o r t a n c e t o t h e s e as l o c io f m i n e r a l i z i n g s o l u t i o n s and d e p o s i t i o n o f o r em i n e r a l s .

C a r e f u l m a p p i n g o f s e v e r a l h u n d r e d j o i n t si n t h e d i s t r i c t f a i l e d t o i n d i c a t e any a p p a r e n tr e l a t i o n s h i p o f t r e n d o f j o i n t s t o t r e n d of a r eb o d i e s . At t h e Newton and McNal ly m i n e s on t h eW h i t e R e e f one m i g h t be i n c l i n e d t o a t t a c h im -po r t ance t o th e j o i n t s as some of th e s t o p e s a p p e a rto end a g a i n s t them. Assays of s i l v e r beyond th ej o i n t f a c e i n m o s t c a s e s , h o w e v e r , a p p r o x i m a t et hose i n p i l l a r s of th e o ld s t o p e s . A p p a r e n t l y th ej o i n t s o f f e r e d an e a s y b r e a k i n g s u r f a c e d u r i n gb l a s t i n g . The j o i n t p a t t e r n d o u b t l e s s was formedb e f o r e th e s i l v e r c h l o r i d e m i n e r a l i z a t i o n as s i l v e ro c c u r r e d i n t h e c l a y f i l l ing o f some o f t h e m .

F a u l t s and S h e a r s

F a u l t s a r e n o t a b u n d a n t i n t h e H a r r i s b u r gmin ing d i s t r i c t . The g r e a t e s t number i s on t h e

n o s e o f th e Vi r g i n a n t i c l i n e where t h e y d i s p l a c et h e S i l v e r R e e f s a n d s t o n e . On t h e Whi te R e e f a

f o s s i l p l a n t h o r i zon now r e p l a c e d by c o p p e r c a r b o n -a t e s i s d i s p l a c e d 50 f e e t on an o b l i q u e f a u l tn o r t h o f t h e Barbee and Walker Mine . On TecumsehH i l l s e v e r a l s m a l l f a u l t s d i s p l a c e t h e o re h o r i z o na few f e e t . The T r a i l H i l l f a u l t d rops t h e h a n g -i n g w a l l o f Tecumseh and L e e d s s a n d s t o n e t o t h ee a s t , b u t i t i s n o t known w h e t h e r th e d o w n f a u l t e ds a n d s t o n e c o n t a i n s s i l v e r . I t i s p o s s i b l e t h a tt h e o re i t se l f h a s n o t b e e n d i s p l a c e d , b u t o n l yt h e h o r i z o n t h a t was s u s c e p t i b l e t o m i n e r a l i z a t i o n .

The s h e a r which b e g i n s i n th e C a l i f o r n i a mineand t r e n d s n o r t h s u g g e s t s a r e l a t i o n s h i p t o o rem i n e r a l i z a t i o n . Two s t o p e s , one more t h a n 200f e e t l o n g and a l m o s t 70 f e e t w i d e , a r e s o u t h e a s to f t h e S a v a g e s h a f t . The s t o p e s i n d i c a t e t h a tm i n e r a l i z a t i o n o c c u r r e d i n t h e l a v ~ n d e rt o b u f f -brown s a n d s t o n e s . Nor th o f t h e C a l i f o r n i a andMaggie m i n e s a l m o s t a l l o f t h e known s t o p e s end

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on t h e p r o j e c t i o n o f t h i s same s h e a r z o n e . An

e x c e p t i o n occu r s s o u t h o f th e above s u r f a c e s t o p e swhere min ing was c a r r i e d t o t h e f a c e of th e r e e f .

Other than t h i s , th e g e n e r a l a l ignment of the s t a p e sa l o n g t h e b r e a k s t r o n g l y s u g g e s t s t h a t t h e zoneac t ed as a pathway f o r th e supergene a re s o l u t i o n s .I t may have c o n t r o l l e d t o some e x t e n t th e m i n e r a l iz a t i o n above and below i t . At th e C a l i f o r n i a mines u r f a c e s t o p e , a r e was mined f rom th e s h e a r zoneand a r e l a t e d s h a r p f l e x u r e . The s h e a r zone i sa t l e a s t 10 f e e t wide and t h e f o l d much w i d e r .Mining c e a s e d when t h e beds assumed a more g e n t l e

d i p . Another t ype o f s h e a r i n g ment ioned by B u t l e r( p . 5 8 8 , 1 9 2 0 ) o c c u r s i n t h e i n t e r b e d d e d s h a l e sand i n t h e h o r i z o n s of s m a l l c l a y b a l l s and g a l l s .Dur ing movement o f t h e b e d s , t h e s e were somewhats h e a r e d and s i l v e r m i n e r a l s a r e r e p o r t e d t o havec o a t e d many o f t h e f r a c t u r e f a c e s . O t h e r t h a nt h e s e s u g g e s t i v e r e l a t i o n s h i p s o f s h e a r s t o a rel o c a l i z a t i o n , m o s t o f t h e s i l v e r - c a p p e r - u r a n i u mb o d i e s show l i t t l e or no s p a t i a l r e l a t i o n t o t h e s es t r u c t u r e s .

F i g u r e 7 . S m a l l f a u l t s , Buckeye and L a s t Chancem i n e s . ( A f t e r R o l k e r , p . 2 9 , 1 8 8 1 ) .



C h e m i c a l R e l a t i o n s h i p s o f M i n e r a l i z a t i o n

R e l a t i o n of S i l v e r , C o p p e r, and Uraniumt o C a r b o n i z e d S u b s t a n c e

A d i r e c t r e l a t i o n s h i p e x i s t s b e t w e e n t h es i l v e r c o p p e r and u r a n i u m - v a n a d i u m m i n e r a l s andt h e f o s s i l p l a n t s . I t i s a l m o s t u n i v e r s a l f o r t h ec o p p e r m i n e r a l i z a t i o n , and a l i t t l e l e s s s o f o rt h e s i l v e r . A p p a r e n t l y , t h e u r a n i u m - v a n a d i u mm i n e r a l s may be d e p o s i t e d w i t h o r w i t h o u t v i s i b l ef o s s i l p l a n t s u b s t a n c e . Not o n l y d i d t h e s m a l l e rp l a n t f o s s i l s a c t as l o c i f o r d e p o s i t i o n o f t h em i n e r a l s , b u t l a r g e f o s s i l t r e e s were a l s o i m p o rt a n t . B a l l ( 1 9 2 0 ) r e p o r t s t h a t one f o s s i l t r e ey i e l d e d $ 1 4 , 0 0 0 i n s i l v e r . S m a l l p i e c e s o f c a rb o n i z e d w o o d , some l ign i t i c i n c h a r a c t e r , a r es t i l l v i s i b l e i n some o f t h e a c c e s s i b l e w o r k i n g s .M o s t o f t h e s e h a v e a h i g h s i l v e r c o n t e n t . A l lknown m i n e r a l i z e d f o s s i l t r e e s i n t h e S i l v e r R e e fs a n d s t o n e , a s would be e x p e c t e d h a v e b e e n m i n e d .

R e l a t i o n o f S i l v e r C o n t e n tt o C a r b o n a t e C o n t e n t

B a l l (1920) s u g g e s t e d t h a t a d i r e c t r e l a t i o ns h i p m i g h t e x i s t b e t w e e n t h e s i l v e r c o n t e n t andt h e c a r b o n a t e c o n t e n t o f t h e s a n d s t o n e . He p o s t ul a t e d t h a t t h e s i l v e r m i n e r a l o c c u r s as a r e p l a c e

m e n t o f t h e c a r b o n a t e . A n a l y s e s o f s a m p l e s f o rc a r b o n a t e c o n t e n t f rom t h e t o t a l t h i c k n e s s o f bo tht h e Buckeye and White Reef f a i l e d t o show any d i r e c tr e l a t i o n s h i p t o s i l v e r c o n t e n t . The few a v a i l a b l es p e c i m e n s o f s i l v e r o r e d i d n o t r e p l a c e c a r b o n a t emine ra l s as i n d i c a t e d by m i c r o s c o p i c s t u d y. However,t h e p o s s i b i l i t y r e m a i n s t h a t t h e dr i l l c o r e s a n a ly z e d f o r c a r b o n a t e c o n t e n t were n o t r e p r e s e n t a t i v eo f t h e a r e r o c k , s i n c e v a l u e s i n t h e dr i l l c o r e s

w e r e l o w. F i g u r e5

s h o w s t h e r e s u l t s o f one o ft h e s e a n a l y s e s . U n h a p p i l y, t h e o p e r a t o r s t h o u g h ti t u n n e c e s s a r y t o a n a l y z e f o r any o t h e r e l e m e n t st h a n s i l v e r and c o p p e r , s o t h e many h u n d r e d s o fa v a i l a b l e a s s a y s a re o f nn u se i n such a c o m p a r i s o n .

- 101 -



R e l a t i o n o f S i l v e r t o Copper Conten t

I t h as b e e n s t a t e d by some of t h e o ld r e s i

d e n t s i n t h e a r e a t h a t h i g h s i l v e r and coppe r cont e n t w e r e n o t g e n e r a l l y a s s o c i a t e d i n t h e sameo re h o r i z o n . I n t h e p r e s e n t s t u d y i t was t h o u g h tt h a t i f a p o s s i b l e r e l a t i o n s h i p , e i t h e r d i r e c tor i n v e r s e , d i d e x i s t b e t w e e n t h e s i l v e r - c o p p e rr a t i o a means o f r o u g h l y p r e d i c t i n g t h e p r e s e n c eo r a b s e n c e o f s i l v e r f rom t h e v i s u a l amount o fc o p p e r m i n e r a l p r e s e n t m i g h t be p o s s i b l e . A r a ndom s e l e c t i o n of a p p r o x i m a t e l y 200 ana lyzed samples

f rom b o t h t h e White and Buckeye R e e f was comparedt o n o t e any p o s s i b l e q u a n t i t a t i v e r e l a t io n s h i pb e t w e e n th e two m e t a l s . F i g u r e 6 shows th e r e s u l t so f t h i s s t u d y . S i n c e company r e g u l a t i o n s do n o tp e r m i t p u b l i s h i n g o f th e a c t u a l v a l u e s , a l o g a r i t hm ic r a t i o w i t h no v a l u e s a s s i g n e d f o r t h e s i l v e ran d c o p p e r was u s e d f o r p l o t t i n g p u r p o s e s . Theg r a p h i s d r a w n t o show t h e c o p p e r v a l u e s as a

c o n t i n u o u s l y i n c r e a s i n g f u n c t i o n , and t h e s i l v e ras t h e v a r i a b l e .

The m o s t d i s t i n c t i v e f e a t u r e o f th e graph i st h e wide v a r i a t i o n i n th e s i l v e r c o n t e n t when comp a r e d t o a c o n s t a n t l y i n c r e a s i n g c o p p e r c o n t e n t .The Buckeye Reef samples show no a p p a r e n t r e l a t i o ns h i p . T h e r e i s , h o w e v e r, a s l i g h t i n d i c a t i o n o fa p o s s i b l e i n c r e a s e o f s i l v e r c o n t e n t wi th i n c r e a s ei n

coppe rf o r t h e

White R e e f .Such a r e l a t i o n s h i p

would app ly t o t h e a v e r a g e c a s e and n o t a s p e c i f i cone , however. A s t u d y of a g r e a t e r number o f samp l e s t h a n were a v a i l a b l e mi gh t f u r t h e r s u b s t a n t i a t et h i s . I t i s q u i t e a p p a r e n t t h a t t h e p r e s e n c e o fc o p p e r does n o t p r e c l u d e h i g h s i l v e r c o n t e n t , nord o e s t h e q u a n t i t y o f c o p p e r i n t h e o r e a p p e a r t oo f f e r any p o s s i b i l i t y o f p r e d i c t i n g t h e a s s o c i a t e ds i l v e r c o n t e n t .

R e l a t i o n of S i l v e r Con ten tt o R a d i o - A c t i v e M i n e r a l s

S i n c e t h e r e a re only a few p l a c e s i n t h e d i st r i c t whe re t h e u r a n i u m - v a n a d i u m m i n e r a l s o c c u ri n any amount , and t h e s e l o c a l i t i e s a re main ly o u t -



s i d e o f th e main s i l v e r mining a r e a , few a s s a y s werea v a i l a b l e f o r s t u d y. However, th e l a c k o f e x t e n s i v emining o p e r a t i o n s n e a r t h e o c c u r r e n c e s i s i n d i c a t i v eof low s i l v e r v a l u e s . S e v e r a l samples with a p p r o x imate ly 2 p e r c e n t c a r n o t i t e and some copper c a r b o n a t ewere a s s a y e d f o r s i l v e r , b u t i n e a c h sample t h e r et u r n s were l ow. The h i g h e s t a v e r a g e d 6 . 6 0 o u n c e so f s i l v e r p e r t o n , 2 . 5 8 p e r c e n t of c o p p e r, and someu r a n i u m - v a n a d i u m . F i g u r e 8 i s a c o m p i l a t i o n o fa s s a y s f o r u r a n i u m , v a n a d i u m , s i l v e r , c o p p e r ands e l e n i u m . The twe lve s i l v e r s a m p l e s do n o t a p p e a rt o show any d i r e c t r e l a t i o n s h i p t o th e r a d i o - a c t i v em i n e r a l c o n t e n t .

R e l a t i o n of R a d i o - A c t i v e M i n e r a l st o Copper, Vanadium, and Se len ium

T h i r t y - n i n e a n a l y s e s , made a v a i l a b l e by t h eU n i t e d S t a t e s G e o l o g i c a l S u r v e y, ( S t u g a r d , 1 9 5 1 ) ,w e r e p l o t t e d u s i n g a p r o g r e s s i v e l y in c r e a s i n gu r a n i u m c o n t e n t . I t was h o p e d t h a t any i n v e r s Bo r d i r e c t r e l a t i o n s h i p i n amoun t s o f t h e e l e m e n t sm i g h t be i n d i c a t e d by s u c h a c h a r t . As f i g u r e 8

demons t r a t e s , t he se len ium c o n t e n t i s h i g h l y e r r a t i cand d o e s n o t a p p e a r t o c o r r e s p o n d t o t h e u ran iumc o n t e n t . L i k e w i s e , t h e p e r c e n t c o p p e r i s q u i t ev a r i a b l e and may e i t h e r i n c r e a s e o r d e c r e a s e whenu r a n i u m i s p r e s e n t . S i n c e t h e g r e a t m a j o r i t y o f

t h e u r a n i u mo c c u r s

i n t h e m i n e r a l c a r n o t i t e , ani n c r e a s e i n t h e vanadium c o n t e n t s h o u l d t a k e p l a c ewhen uran ium i n c r e a s e s . T h i s i s i n d i c a t e d i n a

g e n e r a l way. Because vanadium o f t e n t i m e s e x c e e d sth e expec t ed amount , and somet imes i s l e s s t h a n i sr e q u i r e d by t h e c a r n o t i t e f o r m u l a , i t s u g g e s t st h a t bo th uranium and vanadium m i n e r a l s o t h e r t h a nc a r n o t i t e m u s t be p r e s e n t . The e x c e s s v a n a d i u mc a n be a c c o u n t e d f o r i n t h e m i n e r a l v o l b o r t h i t e

( a hydrous v a n a d a t e o f coppe r, b a r i u m , and ca lc ium)w h i l e a u t u n i t e i n m i n u te g r a i n s o r some o t h e r u nknown uran ium m i n e r a l might a c c r u n t f o r t h e e x c e s su r a n i u m .

- 103 -



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U r a n i u m - v a n a d i u m - c o p p e r- s i 1 v e r - s e 1 e n i u mr a t i o s .



MINERALOGY

A r a t h e r s i m p l e a s s e m b l a g e o f m i n e r a l s makeup t h e a r e b e d s and o t h e r s a n d s t o n e s a t S i l v e r

R e e f . C e r a r g y r i t e , t h e m a j o r s i l v e r m i n e r a l , i sa s s o c i a t e d w i t h a h o s t of m i n e r a l s . Both t h e a reand n o n - a r e - b e a r i n g s a n d s t o n e s c o n s i s t e d of 90 p e rc e n t or more of q u a r t z g r a i n s on th e a v e rage , thoughl o c a l l y f e l d s p a r s m i g h t make up 3 0 - 4 0 p e r c e n t o fth e r o c k . G e n e r a l l y, however, f e l d s p a r s , m u s c o v i t e ,c h l o r i t e , c a l c i t e , i r o n o x i d e ; and much l e s s e ramounts of z i r c c n , a p a t i t e ( i n q u a r t z ) , t o u r m a l i n e ,and g a r n e t c o n s t i t u t e d th e l e s s a b u n d a n t m i n e r a l s

o f th e s a n d s t o n e . L o c a l l y, m a l a c h i t e and a z u r i t emake up t o 5 p e r c e n t o f t h e r o c k . C a r n o t i t e andp r o b a b l e a u t u n i t e o c c u r s p o r a d i c a l l y and i n s m a l lamoun t s i n t h e Tecumseh s a n d s t o n e on t h e Buckeyeand E a s t R e e f and i n l e s s e r amoun t s on t h e Whi teReef . O c c a s i o n a l l y, i r o n ox ide n o d u l e s and s t a i n s ,c h a l c o c i t e n o d u l e s , minor p y r i t e , and snme s i l v e rs u l f i d e o c c u r r e d t o g e t h e r . J . S. Newberry (p . 5 ,1881) r e p o r t e d s e l e n iu m i n some o f t h e o r e s . T h i s

was c o n f i r m e d by t h e w r i t e r and a l s o by S t u g a r d( 1 9 5 0 ) . Heavy m i n e r a l s , i . e . , t h o s e a b o v e 2 . 8 0s p e c i f i c g r a v i t y , o c c u r i n v e r y m i n o r q u a n t i t i e si n th e S i l v e r Reef s a n d s t o n e . M i n e r a l o g i c a l s t u d yo f two comple te s e c t i o n s o f th e s a n d s t o n e i n d i c a t e st h a t t h e y do n o t c o n s t i t u t e more t h a n 0 . 1 p e r c e n tby weigh t f o r a l l g r a i n s i z e s .

C e r a r g y r i t e , Agel

C e r a r g y r i t e was t h e p r i n c i p a l o r e m i n e r a lo f t h e o ld m i n i n g camp and i t s d i s c o v e r y by W. T.B a r b e e on Tecumseh H i l l b r o u g h t a b o u t t h e "boom"m i n i n g i n t h e d i s t r i c t . The m i n e r a l o c c u r r e d i na l l o f t h e s i l v e r o r e s and was commonly c a l l e d"horn s i l v e r " or " c h l o r i d e of s i l v e r " by th e m i n e r s .

G e n e r a l l y , i t was found as a waxy v i o l e t t o brownm i n e r a l , t hough i n some mines i t was w h i t e t o g rayand b l e n d e d p e r f e c t l y wi t h t h e l i g h t c o l o r e d s a n ds t o n e s . On exposure t o l i g h t , th e whi te c e r a r g y r i t eg r a d u a l l y changed t o v i o l e t - b r o w n .

- 105 -



The m i n e r a l ~ a s d i s semina ted ~ i t h i nth e s i l v e rb e a r i n g s a n d s t o n e s , or occur red as t h i n p l a t e s alongt h e b e d d i n g p l a n e s , s u r f a c e f i l m s on s h e a r p l a n e s

i n sands tone and s h a l e , and as r e p l a c e m e n t s o f c a rb o n i z e d ~ o o do r s m a l l e r p l a n t f o s s i l s ( P l a t e X ).Though i t has been r e p o r t e d t h a t s i l i c i f i e d t r e e ss e l d o m c o n t a i n e d t h e s i l v e r c h l o r i d e , s e l e c t e ds i l i c i f i e d f r a g m e n t s k n o ~ nt o have o c c u r r e d abovet h e wate r t a b l e were as sayed and gave t h e f o l l o w i n gr e s u l t s :

Gold - t r a c e

S i l v e r - 12.90 o z s . / t o nI r o n - 0.4%Copper - 0.4%I n s o l u b l e - 96.0%

Embol i t e (?), Ag (Br,C l )

Though n o t i d e n t i f i e d o r c o n f i r m e d by t h ew r i t e r , t h e d e s c r i p t i o n by M e s s r s . H a r t l e y , Mc-M u l l i n , and Colba th o f a r a r e g r e e n s i l v e r m i n e r a lwhich t h e y c a l l e d " s i l v e r b r o m i d e " , mos t c l o s e l yr e sembles t h a t of e m b o l i t e , a s i l v e r - c h l o r o - b r o m i d ew i t h c o l o r a g r a y i s h g r e e n t o y e l l o w i s h g r e e n o ry e l l o w. Such a m i n e r a l would n o t be u n e x p e c t e di n t h e o x i d i z e d z o n e . E x t e n d e d s e a r c h o f t h edumps, howeve r, f a i l e d t o r e v e a l i t . The m i n e r a lt h e min ing men d e s c r i b e d came from t h e Cobb m i n ~

N a t i v e S i l v e r , Ag

Though t h i s m i n e r a l was n o t c o n f i r m e d by th ew r i t e r , s e v e r a l o f t h e fo rmer g e o l o g i s t s and manyof t h e o ld m i n e r s i n t h e d i s t r i c t v e r i f y i t s p r es e n c e . Accord ing t o McMull in ( p e r s o n a l communica-t i o n , 1947) n a t i v e s i l v e r was l o c a l l y abundan t i nt h e Thompson Mine on t h e White R e e f . He r e p o r t st h a t some rock spec imens when broken with a hammerwould n o t f a l l a p a r t b e c a u s e of t h e t e n a c i t y o ft h e w i r e s i l v e r . S m a l l s p e c k s 0 f n a t i v e s i l v e rwere a l s o r e p o r t e d on t h e s h e a r e d f a c e s o f s h a l eJ e n n e y (P . 464 , 1902) q u o t e s N e s b i t t as s a y i n g :



abou t 100 t o 200 f e e t above w a t e r l e v e lon t h e s l o p e o f th e beds ( i n t h e Barbeeand Walker Mine) t h e o re was v e r y r i c h ,and s m a l l b u n c h e s of l i g n i t e c o a l , 4 t o10 i n c h e s a c r o s s , were f o u n d imbedded

i n t h e s o f t s a n d s t o n e w i t h n a t i v e s i l -v e r d e p o s i t e d on t h i n s c a l e s 0n t h ej o i n t s of t h e c o a l . Most of th e o re a tt h i s d e p t h was s i l v e r s u l p h i d e .

S i l v e r S e l e n i d e (? )

Newber ry ( p . 5 , 1881 ) s t a t e s t h a t some o ft h e o r e s a t S i l v e r Reef c o n t a i n e d s e l e n i u m . He

n o t e d t h a t t h e a v e r a g e o f f o u r a n a l y s e s o f a r ey i e l d e d 0 . 2 3 p e r c e n t s e l e n i u m and 0 . 2 6 p e r c e n ts i l v e r . One o t h e r o r e s p e c i m e n i s r e p o r t e d t oh a v e y i e l d e d 90 o u n c e s o f s e l e n i u m t o t h e t o n .Unhapp i ly, Newberry does n o t l i s t th e l o c a t i o n ofth e s a m p l e s , e i t h e r as t o mine or d e p t h below t h es u r f a c e . B u t l e r ( p . 5 9 2 , 1920 ) n o t e s t h a t t h ese len ium m i g h t s u g g e s t t h a t p a r t o f th e s i l v e r cont e n t o f t h e s a n d s t o n e was combined i n s ~ m eform

with i t . R e c a l c u l a t i o n o f Newber r y ' s a n a l y s e s t oa p o s s i b l e s i l v e r - s e l e n i u m c o m p o s i t i o n y i e l d sAg 2 Se3 i f i t be c o n s i d e r e d t h a t i t combined whol lywi th th e s i l v e r . As f a r as i s known no such m i n e r a le x i s t s , nor do th e e l e m e n t v a l e n c e s i n d i c a t e sucha c o m p o s i t i o n . However, t h e se l en ium r e p o r t e d byNewberry c o u l d ha v e b e e n w i t h o t h e r e l e m e n t s andn o t b e a r any r e l a t i o n s h i p t o s i l v e r c o n t e n t . Ana l y s i s by M. C o l l e r f o r th e w r i t e r of a r i c h f i n eg r a i n e d s i l v e r a r e s p e c i m e n f rom t h e Cobb mines t a p e s above wate r t a b l e y i e l d e d 46.23% s i l v e r and16.66% s e l e n i u m . X-ray p a t t e r n s i n d i c a t e d c e r a rg y r i t e l i n e s , p o s s i b l e a r g e n t i t e (Ag2S) l i n e s , andsome q u a r t z . As f a r as c o u l d be d e t e r m i n e d t h eX-ray r e f l e c t i o n l i n e s f o r a g u i l a r i t e /Ag2(S ,Se) . /w e r e n o t a p p a r e n t . O t h e r s a m p l e s s h o w e d goodp a t t e r n s f o r c e r a r g y r i t e .

A rg e n t i t e (? ) Ag 2 S

Argen t i t e was no t apparent i n any of th e samplesc o l l e c t e d i n t h e min ing d i s t r i c t , e x c e p t f o r t h e

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i n d i c a t i o n i n th e sample above. Very c a r e f u l s e a r c ho f th e mine dumps f a i l e d t o show any. B a l l as l a t eas 1920 r e p o r t s t h a t he cou ld f i n d no m i n e r a l s p e c imens f o r t h e s i l v e r s u l f i d e r e p o r t e d by f o r m e re n g i n e e r s and g e o l o g i s t s who had w o r k e d i n th ea r e a . A p p a r e n t l y , m o s t o f t h e v i s i b l e o re wasm i l l e d and l i t t l e o f t h e h i g h e r g r a d e o re l e f t ont h e dumps.

R o l k e r ( p . 26 , 1881) f i r s t r e p o r t e d :

The o re i t s e l f i s what i s known as c e ra r g y r i t e o r c h l o r i d e o f s i l v e r , whichh o w e v e r , b e l o w t r u e w a t e r - l e v e l w i l lc h a n g e t o s u l p h u r e t o f s i l v e r , w i t hn a t i v e s i l v e r i n p l a c e s .

T he o l d m i n e r s s t a t e t h a t i n f o s s i l t r e e sa t d e p t h s w i t h i n t h e m i n e s , two k i n d s o f s i l v e ro re e x i s t e d , t h e s u l f i d e o f s i l v e r and t h e s i l v e rc h l o r i d e . The L e e d s , Savage , and C a l i f o r n i a minesa r e r e p o r t e d t o h a v e h ad b o t h m i n e r a l s p r e s e n t .W. M. N e s b i t t , who w o r k e d a t S i l v e r R e e f f rom1 8 7 8 - 8 8 , s t a t e d t o W. P. J e n n e y ( p . 4 6 4 , 1 9 0 2 ) :

At one p l a c e a t r e e t r u n k , 18 i n c h e s i nd i a m e t e r was f o u n d , t h e h e a r t wood wass i l i c i f i e d and v e r y h a r d , and c a r r i e d8-10 ounces of s i l v e r p e r t o n . The sa pwood and b a r k , 3 - 6 i n c h e s t h i c k , werea l t e r e d t o s o f t c r u m b l i n g l i g n i t e f u l lo f s i l v e r s u l p h i d e , i t a s s a y e d 5 , 0 0 0o u n c e s o f s i l v e r p e r t o n .

M a l a c h i t e CuC03 .Cu(OH)2

M a l a c h i t e , th e g r e e n c o p p e r c a r b o n a t e m i n e r a l ,i s th e most common c o p p e r m i n e r a l i n t h e d i s t r i c t .I t r e p l a c e s fo rmer p l a n t m a t e r i a l and r a r e l y occursd i s s e m i n a t e d w i t h i n t h e s a n d s t o n e . L o c a l l y , i t

i s found as s t a i n s i n t h e r o c k and as r e p l a c e m e n t so f woody m a t e r i a l . Only r a r e l y does i t c o m p l e t e l yr e p l a c e f r a g m e n t s o f f o s s i l t r e e s . The m i n e r a lo c c u r s a l m o s t u n i v e r s a l l y i n w h i t e o r b u f f s a n ds t o n e and only s p o r a d i c a l l y i n l a v e n d e r s a n d s t o n e s .Under th e microscope th e m a l a c h i t e occur s as f i n e l yr a d i a t i n g m a s s e s b e t w e e n t h e q u a r t z g r a i n s andappears t o r e p l a c e th e k a o l i n groundmass. ( P l a t e IX) .

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The m i n e r a l i s most common on t h e White andE a s t Ree f , b u t i t i s l o c a l l y a b u n d a n t on t h e Buck-eye R e e f . The b e s t o c c u r r e n c e s a re on t h e EmilyJane p r o p e r t y nea r th e Thompson Mine, i n th e NewtonMine t o t h e n o r t h , and on t h e Maud c l a i m on t h e

E a s t Reef where i t l o c a l l y c o n s t i t u t e s 5 p e r c e n to f a b u f f , f i n e - g r a i n e d s a n d s t o n e c o n t a i n i n g abun-d a n t p l a n t f o s s i l s .

A z u r i t e , 2CuC0 3 ·Cu(OH)2

A z u r i t e o c c u r s o n l y w i t h m a l a c h i t e and h asn o t been r e p o r t e d o r o b s e r v e d t o o c c u r s i n g l y i nt h e d i s t r i c t . The r a t i o o f m a l a c h i t e t o a z u r i t ea p p r o x i m a t e s 1 0 - 1 . The m o s t a b u n d a n t s h o w i n g sa r e i n t h e Leeds Mine and i n t h e Newton w o r k i n g ~

I t s o c c u r r e n c e i s i d e n t i c a l t o t h a t o f m a l a c h i t e .

C u p r i t e , Cu2 0

C u p r i t e o c c u r s i n m i n u t e q u a n t i t i e s i n someo f t he copper s t a i n e d b u f f , f i n e - g r a i n e d s a n d s t o n e s .Rolker (p . 27, 1881) observed :

a n o t h e r f r e q u e n t o c c u r r e n c e i s a f o o to r two f o o t seam o f s a n d s t o n e f u l l o f

p e t r i f i c a t i o n s , c h a rg e d w i t h r e d o x i d eo f c o p p e r , a z u r i t e , an d m a l a c h i t e t osome e x t e n t and c a r r y i n g no s i l v e r .

The American Cyanimid Ore D r e s s i n g L a b o r a t o r y(1946) a l s o n o t e d c u p r i t e i n m i n u t e q u a n t i t i e s i nsome of t h e o re c o n c e n t r a t i o n s .

Te n o r i t e , CuO

B a l l ( 1 9 2 0 ) r e p o r t s t h e p o s s i b l e p r e s e n c eo f t e n o r i t e , b u t was n o t c e r t a i n o f i t s i d e n t i f ic a t i o n . The w r i t e r cou ld no t v e r i f y th e occu r r encei n th e d i s t r i c t .

C h a l c o c i t e Cu2 S

C h a l c o c i t e i s n o t an a b u n d a n t m i n e r a l i n th ed i s t r i c t . I t most commonly o c c u r s as sma l l n o d u l e sas much as 1 / 2 inch or more i n d i a m e t e r. The o u t e r

s u r f a c e shows a r u s t y brown c o a t i n g , t h o u g h t h ef r e s h m i n e r a l h a s t h e c h a r a c t e r i s t i c l e a d g r a yc o l o r o f c h a l c o c i t e . Many n o d u l e s o c c u r i n b u f ft o whi t e s a n d s t o n e on t h e Emily J ane p r o p e r t y and

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P l a t e IX. PHOTOMICROGRAPHS OF MINERAL OCCURRENCES

A. Malach i t e (medium gray) aroundq u a r t z g r a i n s ( 1 5 x ) .

B. P a r t i a l r e p l a c e m e n t of p l a n t r ema insby c a r n o t i t e ( 1 5 x ) .

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P l a t e X. PHOTOMICROGRAPHS OF MINERAL OCCURRENCES

A. C e r a r g y r i t e ( b l a c k ) i n q u a r t z s a n d s t o n e( w h i t e ) . E l o n g a t e p l a t e s a re muscov i t e ( 1 5 x ) .

B. I r o n ox ide ( b l a c k ) f i l l i n g around q u a r t zg r a i n s ( w h i t e ) . L i g h t gray r ims aroundq u a r t z ( l ower l e f t ) a r e c a r n o t i t e ( 1 5 x ) .

- I I I -



a ~ t h e S o u t h Thompson , Cobb , and D u f f i n mines •.Some o f th e o l d e r m i n e r s r e p o r t o c c u r r e n c e s i n th eBarbee and Walke r, L a s t Chance , and Tecumseh mine&Smal l n o d u l e s o f t h e m i n e r a l a re a l s o found s o u t ho f t h e D u ff i n Mine on t h e E a s t R e e f .

C h a l c o c i t e c o n c r e t i o n s more t h a n an i n c h i nd i a m e t e r o c c u r below t h e S i l v e r Reef s a n d s t o n e i nt h e F i r e C l a y H i l l b e n t o n i t i c s h a l e s . H a r t l e y( p e r s o n a l communicat ion) r e p o r t s t h a t he found someas much as s i x i nches i n d i a m e t e r. C a r e f u l r e s e a r c ho f t h e a r e a , however, f a i l e d t o r e v e a l any c o n c r e -t i o n s t h a t s i z e , t h o u g h one i n c h s i z e s o c c u r r e dl o c a l l y . The c o n c r e t i o n s c o u l d e a s i l y be o v e r -l ooked as t h e i r e x t e r n a l appearance i s a lmos t i d e n -t i c a l wi th th e t h o u s a n d s o f c a l c a r e o u s c o n c r e t i o n swhich o c c u r i n t h e same b e d . Some o f t h e c h a l c o -c i t e c o n c r e t i o n s have a c o a t i n g o f m a l a c h i t e andi r o n o x i d e . S t u d y o f p o l i s h e d s e c t i o n s o f someo f th e spec imens i n d i c a t e s t h a t c h a l c o c i t e u n i v e r -s a l l y r e p l a c e s p y r i t e and i s i n t u r n r e p l a c e d by

s i l i c a . (See p l a t e XIA

and B ).C h a l c o D v r i t e and B o r n i t e

CuFeS2 and CU5FeS4

Though no c h a l c o p y r i t e was found by th e w r i t e r ,t h e Amer ican Cyanimid Ore D r e s s i n g L a b o r a t o r y r e -p o r t e d v e r y minor amounts of b o t h c h a l c o p y r i t e andb o r n i t e i n o re c o n c e n t r a t e s from th e S i l v e r Reef .

Dr.Hyrum

S c h n e i d e r , e m e r i t u s p r o f e s s o r o f geo logya t t h e U n i v e r s i t y o f U t a h , r e c o g n i z e d b o r n i t e i na s m a l l l e n s o f s u l p h i d e s r e p l a c i n g s i l i c i f i e dwood. Smal l specks o f th e same m i n e r a l a s s o c i a t e dw i t h p y r i t e and c h a l c o c i t e r e p l a c e d c a r b o n i z e dwood f ragments i n th e ore hor i zon on th e Maud c l a im .

P y r i t e , FeS 2

P y r i t e i s a r a t h e r r a r e m i n e r a l i n th e d i s t r i c tthough th e prominen t l o c a l i r o n - o x i d e s t a i n s s u g g e s ta much w i d e r d i s t r i b u t i o n o r i g i n a l l y . N e s b i t tr e p o r t e d t o Jenney (P . 464 1902) t h a t p y r i t e o c c u rr e d i n t h e B a r b e e and Wa l k e r m a i n i n c l i n e , andt h a t some appe a red a t th e w a t e r t a b l e . The w r i t e r

- 112 -



r e c o g n i z e d p y r i t e f rom a s p e c i m e n o f h i g h g r a d es i l v e r o r e r e p l a c i n g l i g n i t i c m a t e r i a l f rom430 f e e t down i n t h e A. S. & R. s h a f t . As d e -s c r i b e d a b o v e , p y r i t e i s p a r t l y r e p l a c e d byc h a l c o c i t e i n t h e s m a l l c o n c r e t i o n s i n t h e F i r e

Clay H i l l b e n t o n i t i c s h a l e s . O t h e r o c c u r r e n c e swere no ted i n th e Cobb Mine, South Thompson Mine,Emi ly J a n e p r o p e r t y , and t h e Maud c l a i m on t h eE a s t R e e f .

C a r n o t i t e o c c u r s as a d i s s e m i n a t e d m i n e r a lr e p l a c i n g t h e cem en t o f b u f f t o w h i t e s a n d s t o n e

and as a c o a t i n g ~ r o u n dt h e q u a r t z g r a i n s . Lesso f t e n i t i s found i n l a v e n d e r s a n d s t o n e i n a s s o c i -a t i o n w i t h p l a n t f o s s i l s . Under t h e m i c r o s c o p em o s t o f t h e g r a i n s show a y e l l o w t o y e l l o w i s hg r e e n c o l o r , and a p p e a r t o f i l l i n b e t w e e n t h eg r a i n s o f q u a r t z r e p l a c i n g th e k a o l i n groundmass .In two spec imens from n e a r th e Doyle s h a f t c a r n o -t i t e has r e p l a c e d o r t h o c l a s e f e l d s p a r , and i n a n -o t h e r spec imen h a s r e p l a c e d a k a o l i n i z e d r e l i c o fa f o r m e r f e l d s p a r c r y s t a l . Commonly i r o n o x i d es t a i n s o c c u r wi th t h e c a r n o t i t e , b u t whe the r t h e ymere ly s t a i n th e m i n e r a l or were d e p o s i t e d a t th esame t ime i s n o t c l e a r . S i l v e r c h l o r i d e o c c u r r e da s s m a l l v e i n l e t s c u t t i n g t h e c a r n o t i t e i n tw op laces where they occurred t o g e t h e r. (See P l a t e VI) .

The m i n e r a l i s r e p o r t e d i n m i n u t e amoun t s .The lemon t o s u l p h u r y e l l o w hydrous p h o s p h a t e o furan ium and ca l c ium occu r s s p o r a d i c a l l y and s p a r -i n g l y on th e Buckeye and E a s t Reef . Ro lker (p . 5 ,1881) s t a t e s :

I found t h e seams i n which t h e v e g e t a b l er ema ins a re cove red w i t h a u t u n i t e , whichi s q u i t e f r e q u e n t a round t h e Gad s h a f t( e a s t of Savage s h a f t ) and two c a r b o n a t e so f c o p p e r , u n p r o d u c t i v e w i t h pay seamsf r e q u e n t l y above and be low them.

- 113 -



P l a t e XI. DRAWINGS OF PHOTOMICROGRAPHS

A. C h a l c o c i t e ( s t i p p l e d ) r e p l a c i n g p y r i t e(Py) ( 5 0 x ) .

B. Quar tz v e i n i n g and r e p l a c i n g c h a l c o c i t e( s t i p p l e d ) ( 5 0 x ) .

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The q u a n t i t y o f t h e uran ium m i n e r a l i s i ns i g n i f i c a n t i n th e s u r f a c e showings . The m i n e r a loccurs wi th f o s s i l p l a n t s n e a r th e Doyle s h a f t anda l s o r e e d - l i k e and woody s u b s t a n c e i n t h e S i l v e r

Reef s a n d s t o n e on t h e n o r t h p l u n g i n g nose o f t h eVi rg i n a n t i c l i n e . Minute q u a n t i t i e s o c c u r i n th el a v e n d e r s a n d s t o n e n e a r th e Va n d e r b i l t and Duff inmines .

Vo l b o r t h i t e , 6(Cu ,Ca ,Ba)O.V 2 05

. l5H 2 0

Stugard (1951) sugges ted t h a t v o l b o r t h i t e mightbe p r e s e n t i n th e uran ium-vanad ium o r e s . Samples

c o l l e c t e d by th e a u t h o r i n t h e r e c e n t l y excava t edp i t s n e a r t h e Doyle s h a f t show a y e l l o w i s h - g r e e nmicaceous m i n e r a l i n a somewhat i r o n - s t a i n e d s a n ds t o n e . The m i n e ra l commonly occurs a long f r a c t u r e sand as p a r t i a l f i l l i n g s o f open spaces i n th e sands t o n e . More commonly i t o c c u r s as a d a r k o l i v egreen t o ye l low green ex t r eme ly f i n e - g r a i n e d c o a tin g on f r a c t u r e s .

Microscop i c s t u d y i n d i c a t e s y e l l o w i s h - g r e e nhexagona l ly shaped p l a t e s wi th r e f r a c t i v e i n d i c e sr ang ing from 2 .01 t o 2 . 0 3 . The s i g n i s p o s i t i v e .Both th e micaceous a p p e a r i n g m i n e r a l and t he ve ryf i n e - g r a i n e d c o a t i n g s o f a d a r k e r c o l o r have th esame o p t i c a l p r o p e r t i e s . M i c r o c h e m i c a l t e s t sp r o v e a b u n d a n t c o p p e r and v a n a d i u m .

A q u a l i t a t i v e s p e c t r o g r a p h i c a n a l y s i s on a

sample from th e p i t s sou th o f th e Doyle s h a f t gavet he fo l l owing r e s u l t s :

Major e l emen t s : V, CuMinor e l emen t s : ( g r e a t e r t h a n 1%), Ca,

Ba, S i , Fe, Mg, AlTrace e l emen t s : ( l e s s t han 1%), Mn,Ni,

Ag, Zn, Sc, Z r , Co?,S r , Cd, B, Mo, T i , Pb,

C r, Y, K.

Mr. R. K. L e i n i n g e r, s p e c t r o g r a p h e r , r e p o r t s :" In a d d i t i o n , a p o s s i b l e t r a c e of p h o s p h o r o u s wasn o t e d . "

- 115 -



The f i n e - g r a i n e d c h a r a c t e r o f t h e m i n e r a l andi t s r e l a t i v e s c a r c i t y made i t m o s t d i f f i c u l t t oo b t a i n a p u r e s a m p l e . The r e l a t i v e abundance o fS i , F e , Mg, and Al m i g h t be a c c o u n t e d f o r i n t h eq u a r t z and c l a y c o n t e n t o f t h e s a n d s t o n e . A l ld a t a s u g g e s t v o l b o r t h i t e as t h e m i n e r a l .

M i n e r a l o c c u r r e n c e s have b e e n n o t e d i n t h eW i l l i s ' p i t s s o u t h of th e Doyle s h a f t , sou thwardi n th e i n c l i n e on t h e f a c e of th e r e e f , and i n th enew e x p l o r a t i o n p i t s a t t h e n o r t h end of t h e BR e e f , a l s o on Tecumseh H i l l and n e a r t h e o ld gads h a f t .

Gangue M i n e r a l s

A ll of t h e above m i n e r a l s g e n e r a l l y occur i na s s o c i a t i o n w i t h o r n e a r t o t h e s i l v e r - b e a r i n gh o r i z o n s . However, m e n t i o n h a s n o t b e e n made o ft h e more common m i n ~ r a l swhich c o m p r i s e 95% o fth e rock . Cores from two diamond d r i l l h o l e s whichc o m p l e t e l y c u t th e S i l v e r Reef s a n d s t o n e were d i sa g g r e g a t e d i n t o i n d i v i d u a l m i n e r a l f r a g m e n t s bya g e n t l e m o r t a r - p e s t l e t r e a t m e n t . Heavy m i n e r a l swere s e p a r a t e d from t h e l i g h t ( l e s s t h a n 2 .80 s p .g . ) by bromoform. The s e p a r a t i o n i n d i c a t e d t h a t f o rt h e tw o c o m p l e t e s e c t i o n s a n a l y z e d , t h e h e a v ym i n e r a l s c o n s t i t u t e d l e s s t h a n 0 . 1 p e r c e n t byw e i g h t o f t h e i n d i v i d u a l s a m p l e s .

Study of 349 g r a i n s o f a r e p r e s e n t a t i v e s p l i to f 20 f e e t o f t y p i c a l s a n d s t o n e from t h e Tecumsehbeds y i e l d e d t h e r e s u l t s shown i n Tab le 4.

A t y p i c a l 10 f o o t sample o f c o r e f rom n e a rt h e b a s e o f t h e L e e d s s a n d s t o n e was s p l i t downt o a p p r o x i m a t e l y 300 g r a i n s and t h e m i n e r a l s ,i d e n t i f i e d u n d e r t h e m i c r o s c o p e , w i t h th e r e s u l t sshown i n Tab le 5.



Table 4. M i n e r a l o g i c a l Ana lys i sof Tecumseh Sands tone*

L i g h t M i n e r a l s P e r c e n t

Q u a r t z : S u b a n g u l a r g r a i n s i n t h e m a j o r i t y ,m i n o r s u b r o u n d e d , r a r e e u h e d r a l and s u bh e d r a l . The q u a r t z i s m a i n l y c o l o r l e s sw i t h a b u n d a n t i n c l u s i o n s of a p a t i t e ,some t o u r m a l i n e , and z i r c o n . Some g r a i n sshow a h e a v y c o a t i n g of i r o n o x i d e whicha l m o s t c o m p l e t e l y masks th e m i n e r a l . 91.9%

C o l o r 1 e s s q u a r t ze x t i n c t i o n u n d e r

show s prom i n en tc r o s s e d - n i c o l s

wavy-

C o l o r l e s s q u a r t z shows goodg r o w t h w i t h t h e same o p t i c a l

a s t h e o l d e r g r a i n •

s e c o n d a r yo r i e n t a t i o n

O r t h o c l a s e f e l d s p a r : Of t h e few g r a i n s p r es e n t , 50% a p p e a r f r e s h , c o l o r l e s s , ands u b h e d r a l t o a n h e d r a l . On e g r a i n h a swavy e x t i n c t i o n . The r e m a i n i n g g r a i n s

1 . 2%

1 . 2%

a r e very much k a o l i n i z e d and c l o u d y . 2.1%

P l a g i o c l a s e f e l d s p a r : A q u e s t i o n a b l e g r a i no f a n d e s i n e f e l d s p a r and o t h e r s of o l ig o c l a s e c o m p o s i t i o n make up t h e p l a g i oc l a s e g r o u p . The m i n e r a l s a r e p a r t i a l l yk a o l i n i z e d , very c l o u d y, and s u b a n g u l a r . 1.2%

C a l c i t e : A l l f r e e g r a i n s of c a l c i t e a r e v e r ya n g u l a r and c o l o r l e s s , and p r o b a b l y r e -p r e s e n t cement of th e o r i g i n a l s a n d s t o n e . 1.2%

C h l o r i t e : Four g r a i n s of c h l o r i t e were n o t e d .E a c h g r a i n showed t h e common a n o m a l o u si n t e r f e r e n c e c o l o r s u n d e r c r o s s e d n i c o l s .A t l e a s t one g r a i n r e p l a c e d o r i g i n a lh o r n b l e n d e . A l l g r a i n s were s u b a n g u l a r . 1.2%

I r o n - o x i d e a s c o a t i n g s on q u a r t z g r a i n s f a i r l ycommon, and a l m o s t c o m p l e t e l y masked someof t h e q u a r t z . These s t a i n e d g r a i n s haveb e e n lumped u n d e r q u a r t z above . Some mayw e l l be o t h e r m i n e r a l s , t h o u g h s h a p e ,a p p a r e n t r e l i e f a l o n g t h e e d g e s of t h eg r a i n s , and c o l o r l E s s c h a r a c t e r of p a rt i a l l y c l e a n g r a i n s s u g g e s t q u a r t z .

Heavy M i n e r a l s .

To t a l :

None

100%

To t a l g r a i n s c o u n t e d : 349

*From h o l e 5 , 3 6 . 3 - 4 6 . 3 f e e t d e p t h , U.S. S t a n d a r d 1 2 0 -mesh s i z e f r a c t i o n .

- 1 1 7 -





B e s i d e s t h e m i n e r a l s i n Ta b l e s 4 and 5, t h ef o l l o w i n g were o b s e r v e d i n t h i n s e c t i o n s f rom d i ff e r e n t p a r t s of t h e S i l v e r R e e f s a n d s t o n e .

M u s c o v i t e

In c e r t a i n p a r t s of t h e s a n d s t o n e , e s p e c i a l l yt h e midd le s e c t i o n of th e Tecumseh s a n d s t o n e , musco-v i t e commonly o c c u r s as f i n e f l a k e s a l o n g t h e b e dd ing p l a n e s . Much f i n e r g r a i n s occur on th e b e d d i n gp l a n e s o f t h e s h a l e s i n t h e d i s t r i c t . In t h i n s e ct i o n s t h e m u s c o v i t e a p p e a r s as c o l o r l e s s , e l o n g a t eg r a i n s or as a warped p l a t e of m i c a w r a p p i n g a roundt h e q u a r t z g r a i n s . L o c a l l y , t h e m i n e r a l may bel i g h t l y i r o n - s t a i n e d . ( S e e p l a t e X, A ).

K a o l i n i t e (? )

F i n e s h r e d s o f k a o l i n make up p a r t o f t h egroundmass around th e q u a r t z g r a i n s i n th e s a n d s t o n e .The p r o p o r t i o n i s l o w, p r o b a b l y a v e r a g i n g l e s s t h a n3% o f t h e r o c k . I t a l s o o c c u r s as r e p l a c e m e n t s o ff e l d s p a r i n t h e r o c k and o n l y r e l i c t s h a p e s of t h e

f e l d s p a r may r e m a i n .

C a l c i t e

Though c a l c i t e commonly o c c u r s as an i n t e r l o c ki n g c e m e n t a round t h e q u a r t z g r a i n s i n many o f t h ei n d i v i d u a l s a n d s t o n e b e d s i s o l a t e d g r a i n s a l s o mayo c c u r i n t h e w h i t e , f i n e - g r a i n e d Leeds s a n d s t o n e .Near th e Hones t Miner s h a f t and i n th e diamond d r i l lh o l e s n e a r b y, v e i n l e t s of w h i t e t o c o l o r l e s s c a l c i t ea s much a s 1 / 4 i n c h w i d e f i l l many f r a c t u r e s i nt h e r o c k . The m i n e r a l a l s o makes up more t h a n 94% ofth e compos i t ion of some of th e c a l c a r e o u s c o n c r e t i o n si n th e F i r e Clay H i l l b e n t o n i t i c s h a l e s .

Gypsum

Though no gypsum i s known t o occur i n th e S i l v e rReef s a n d s t o n e , i t i s a b u n d a n t as s e l e n i t e i n s m a l lv e i n l e t s and t h i n b e d s i n t h e o v e r l y i n g and u n d e rl y i n g b r i c k - re d s h a l e s of th e S i l v e r Reef a r e a . Noneo f t h e o b s e r v e d o c c u r r e n c e s a r e more t h a n two o rt h r e e i n c h e s t h i c k .

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J a s p e r

J a s p e r does n o t occur i n th e o r e - b e a r i n g membero f t h e C h i n l e f o r m a t i o n , b u t i t s r a t h e r d i s t i n c t i v eoccu r r ence a few f e e t under th e S i l v e r Reef sands tone

a s a g r e e n i s h s h a l e makes i t w o r t h y o f n o t e . Them i n e r a l a p p a r e n t l y · r e p l a c e s t h e s h a l e as an a g g r eg a t e of v e r y f i n e - g r a i n e d , r e d q u a r t z and f o r m s ab e d which i s c o n t i n u o u s o v e r many m i l e s a t p r a c t ic a l l y t h e same h o r i z o n . The m i n e r a l a l s o o c c u r si n t h e F i r e Clay H i l l b e n t o n i t i c s h a l e s g e n e r a l l yn e a r t h e b o t t o m i n a s i m i l a r m a n n e r t o t h e above .Here , h o w e v e r, i t i s banded r e d , g r e e n , y e l l o w, andbrown and may c u t t h e b e d d i n g .

H a l i t e

Though n o t o b s e r v e d i n o u t c r o p , t h e abundanceo f s m a l l s o l u t i o n c a v e - i n s i n t h e s h a l e s a t t h eb a s e o f F i r e Clay H i l l and e a s t w a r d , i s s u g g e s t i v eo f s a l t which h as b e e n d i s s o l v e d away.

M o n t m o r i l l o n i t e

T h i s v a r i e t y o f c l a y makes up a l a r g e p r o p o rt i o n of t h e F i r e Clay H i l l b e n t o n i t i c s h a l e s , andi n some c a s e s may c o n s t i t u t e 60% or more of t h e r o c k .The r o c k composed of th e m i n e r a l i s g e n e r a l l y g r a y -b l u e t o p u r p l i s h and has a common c h e r t - l i k e m i n e r a lc o n c e n t r a t e d a t o r n e a r th e b a s e . Some of th e c l a yg a l l s and b a l l s i n t h e S i l v e r R e e f s a n d s t o n e a l s oc o n t a i n a s m a l l p r o p o r t i o n o f t h e m i n e r a l . The

s w e l l i n g p r o p e r t y of th e c l a y when immersed i n w a t e rand i t s a l mos t com p l e t e d i s a g g r e g a t i o n i s ve ry c h a ra c t e r i s t i c .

A p a t i t e , Z i r c o n , and Tourmal ine

These m i n e r a l s a r e i n t h e m i n o r i t y and u s u a l l yc o n s t i t u t e l e s s t h a n 1 p e r c e n t o f t h e r o c k . Onlyo c c a s i o n a l g r a i n s of t h e m i n e r a l s a r e v i s i b l e i n

t h i n s e c t i o n . Each g r a i n shows i t s c h a r a c t e r i s t i cf e a t u r e s . The a p a t i t e o c c u r s a s i n c l u s i o n s i nq u a r t z a s d o e s some o f t h e t o u r m a l i n e . However,b o t h tourmal ine and z i r c on may occur as i s o l a t e d grainsi n th e m a t r i x of th e s a n d s t o n e . Only t h e t o u r m a l i n ei s c o l o r e d and i t u s u a l l y assumes a l i g h t t o mediumg r e e n .

120





( 1 1 ) . The o c c u r r e n c e o f s i l v e r - and g o l db e a r i n g c h a l c o c i t e - p y r i t e c o n c r e t i o n si n a b e n t o n i t i c s h a l e 310 f e e t be lowt h e S i l v e r Reef s a n d s t o n e .

The occur rence of s i l v e r i n T r i a s s i c s a n d s t o n ea t S i l v e r Reef was a s u b j e c t of l i v e l y d e b a t e f o rmany y e a r s . S e v e r a l t h e o r i e s were o f f e r e d as ane x p l a n a t i o n o f t h e s e un ique d e p o s i t s . The o l d e s tr e c o r d e d t h e o r y known t o t h e w r i t e r was a s h o r tsummary t o t h e e d i t o r of t h e E n g i n e e r i n g and Min

in g J o u r n a l (Mar. 1 2 , 1877) by "C. F. A." who s u gg e s t s t h a t t h e ore was o r i g i n a l l y con t em poraneouswi th t h e s t r a t a , and :

r i c h e s t w h ere t h e r e i s t h e mos t c a r b o n. .. There seems s c a r c e l y room f o r d o u b tt h a t t h e d e p o s i t i on of th e ore s was p e rf e c t l y c o n t e m p o r a n e o u s w i t h t h e f o r m at i o n of t h e s a n d s t o n e s t r a t a i n whichi t l i e s , o r t h a t i t was p r e c i p i t a t e da s c h l o r i d e and n a t i v e s i l v e r a t andd u r i n g t h ~ t i m e t h a t t h e b e d s of s a n dw e r e b e i n g d e p o s i t e d b e f o r e i t becamer o c k , a n d w h i l e t h e y w e r e y e t i n a

h o r i z o n t a l p o s i t i o n .

Newber ry ( p . 2 6 9 , 1880) f a v o r e d a somewhats i m i l a r t h e o r y o f c o n t e m p o r a n e o u s o r i g i n . He

b e l i e v e d t h a t th e m i n e r a l s were p r e c i p i t a t e d froma body of m i n e r a l b e a r i n g w a t e r s by th e a c t i o n ofd e c a y i n g v e g e t a t i o n u n d e r p o s s i b l e m a r i n e c o n d it i ons .

Rothwe l l ( p . 2 5 - 6 , 1880) was f i r s t t o s u g g e s ti n p r i n t t h a t t h e m i n e r a l i z a t i o n had a g e n e t i cr e l a t i o n s h i p t o t h e v o l c a n i c f l o w s i n t h e a r e a .He p o s t u l a t e d t h a t v o l c a n i c

g a s e sand s o l v e n t l i -

q u i d s p a s s e d t h r o u g h t h e s a n d s t o n e a t d e p t h andl e a c h e d t h e m e t a l s f rom t h e r o c k .

Near t h e s u r f a c e where t e m p e r a t u r e andp r e s s u r e s were much l o w e r and v e g e t a b l er e m a i n s p r e s e n t , t h e s i l v e r was p r e c i -



p i t a t e d i n t h e i n s o l u b l e fo rm o f s u l -f i d e s .

Rolke r ( R o l k e r , 1881) fo l lowed i n Augus t , 1880wi th a s i m i l a r t h e o r y :

At t h e t i m e of t h e v o l c a n i c d i s t u r b a n c e ,m e t a l l i c s o l u t i o n s , p r o b a b l y accompan iedby s t eam and v a p o r s a s c e n d e d f rom b e l o wand p e r c o l a t e d t h r o u g h t h e s e s a n d s t o n eb e d s , which a t t h a t t i m e were mos t p o r -ous . The p r e s s u r e d e c r e a s i n g , t h e v e g e -t a b l e r e m a i n s i n some p a r t s , f e r r u g i n o u sm a s s e s i n o t h e r s , p r e c i p i t a t e d t h e s u l -p h u r e t s of s i l v e r (and copper i n p l a c e s ) ,

w h i l e a t o t h e r p o i n t s t h e s i l v e r wasno d o u b t d e p o s i t e d by e v a p o r a t i o n , andn e i t h e r of th e two p r e c i p i t a n t s i s f o u n d ,t h e c a r b o n h a v i n g b e e n c o m p l e t e l y c o n -sumed i n decompos ing t h e m e t a l l i c s a l t s .

L indgren (p . 368 , 1913) wro te t h a t a r g e n t i f e r -ous c h a l c o c i t e f r a g m e n t s were d e p o s i t e d w i t h t h es e d i m e n t s . The f r a g m e n t s were t h e n d i s s o l v e d byc i r c u l a t i n g w a t e r and l a t e r p r e c i p i t a t e d t o formt h e c o m m e r c i a l o re b o d i e s .

B u t l e r ( p . 593 , 1920) i n h i s summary of t h eS i l v e r R e e f d e p o s i t s i s a l m o s t n o n c o m m i t a l a s t oo r i g i n , t h o u g h he d o e s a d m i t t h e p o s s i b i l i t y ofL i n d g r e n ' s t h e o r y . B u t l e r a l s o m e n t i o n s th e p o s -s i b i l i t y of m i n e r a l i z a t i o n b e i n g r e l a t e d t o i gneousa c t i v i t y . However, i n an e a r l i e r s e c t i o n of h i sr e p o r t i n which he summar izes d a t a on d e p o s i t s i ns a n d s t o n e of t h e C o l o r a d o P l a t e a u , he r e g a r d s t h eS i l v e r R e e f t y p e i n much t h e same manner as L i n d -g r e n , i . e . , o r i g i n a l l y d e p o s i t e d as f i n e l y d i s s emin -a t e d m i n e r a l p a r t i c l e s i n t h e s e d i m e n t a r y r o c k s .

B a l l (1920) i s n o t t o o c l e a r i n h i s s t a t e m e n ton t h e t h e o r y of o r i g i n . I n p a r t he f o l l o w s t h ec o n c e p t s o f L i n d g r e n and B u t l e r and s t a t e s t h a tt h e ores w e r e , "sub s e q u e n t l y i n t r oduc ed by c i r c u -I a t i n g w a t e r s " , t h o u g h he d ou b t s t h a t t h e s i 1 v e rwas der ived f rom th e e r os ion of a I1 s i l v e r d i s t r i c t . "He adds :

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. • . t h e w a t e r s were r e l a t i v e l y c o l d b u tw h e t h e r r e m o t e l y c o n n e c t e d w i t h i gneousr o c k s or mere ly mete o r i c w a t e r s of a r t e -s i a n c i r c u l a t i o n we do n o t know.

C r a n e ' s (1920 ) i d e a s were v e r y s i m i l a r t oN e w b e r r y ' s :

• . • i t i s p r o b a b l e t h a t t h e s i l v e r andc op p e r f e d t o t h e s e a from s om e s ou r c e ,were h e l d i n s o l u t i o n a s t h e s u l p h a t eu n t i l b r o u g h t i n t o t h e p r e s e n c e of c a r -b o n a c e o u s m a t t e r , s u c h a s f o s s i l r e e d s

and t r e e s s o common t o t h e ore h o r i z o n ,when t h e y p r e c i p i t a t e d as t h e s u l p h i d e ,o r p o s s i b l y t h e s i l v e r came down i np a r t a s n a t i v e s i l v e r .

F i n a l l y , F i s c h e r (p . 9 4 3 , 1937) i n h i s d i s -c u s s i o n o f s i m i l a r d e p o s i t s of c o p p e r - v a n a d i u muran ium, i n which he i n c l u d e s t h e S i l v e r Reef d ep o s i t s , t h e o r i z e s t h a t t h e d e p o s i t s a r e s y n g e n e t i ci n o r i g i n : (unde r l in ing i n d i c a t e s F i s c h e r ' s i t a l i c s )

• . . s y n g e n e t i c i n th e s e n s e t h a t t h e ~c e n t r a t i o n of t h e m e t a l s occu r r ed a t th et i m e o f t h e d e p o s i t i o n o f t h e b e d s i nwhich t h e y ~ f o u n d . ~ p r e s e n t m i ne r a l s i n a l l c a s e s ~ b e l i e v e d t o bee p i g e n e t i c .

He f u r t h e r s t a t e s (p . 9 4 8 - 9 ) t h a t t h e o r e -b e a r i n g beds of t h e s o u t h w e s t a r e o f t e r r e s t r i a lo r i g i n and were p r o b a b l y formed unde r f l o o d p l a i nc o n d i t i o n s wi th l o c a l b a s i n s fo rming f rom t ime t ot i m e :

I n t h e s e b a s i n s l i v e d or were d e p o s i t e dc e r t a i n organ i sms , p robab ly of th e l owerf o r m s of l i f e , t h a t e i t h e r d i r e c t l y ori n d i r e c t l y c o n c e n t r a t e d t h e s e m e t a l sf rom d i l u t e s o l u t i o n s . I n a l l p r o b a -b i l i t y th e organ isms t h a t were r e s p o n s i -b l e f o r t h e c o n c e n t r a t i o n of th e v a n a -dium ( and uran ium) d i f f e r e d f rom t h o s e

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t h a t c o n c e n t r a t e d t h e c o p p e r an d t h es i l v e r . The fo rm i n w h i c h t h e m e t a l sw e r e o r i g i n a l l y d e p o s i t e d and c o n c e n -t r a t e d i s n o t known, p o s s i b l y t h e y werei n a c o l l o i d a l s t a t e o r p o s s i b l y t h e ywere a b s o r b e d by c e r t a i n m a t e r i a l p r e -s e n t . With t h e n e x t s h i f t of c u r r e n t s ,p o s s i b l y t h e n e x t f l o o d , t h e m e t a l r i c hm a t e r i a l s t h a t a c c u m u l a t e d i n t h e s eb a s i n s were s w e p t away and r e d e p o s i t e di n th e b e d s i n which t hey a re no w f o u n d .

In a l a t e r p u b l i c a t i o n on th e vanadium d e p o s i t s

o n l y, F i s c h e r ' s (pp . 363-94 , 1942) o r i g i n a l workinghypo the s i s i s n o t ment ioned .

The o r i g i n of t h e o re and t h e f a c t o r st h a t c o n t r o l l e d l o c a l i z a t i o n c a n n o t y e tbe s a t i s f a c t o r i l y e x p l a i n e d . The o rem i n e r a l s i m p r e g n a t e t h e s a n d s t o n e andi n t h e i r p r e s e n t f o r m w e r e d e p o s i t e dfrom s o l u t i o n s a f t e r t h e s a n d s were d e -

p o s i t e db u t t h e

n a t u r e oft h e

s o l u t i o n si s n o t u n d e r s t o o d , n o r i s t h e i m m e d i a t es o u r c e o f t h e m e t a l s a p p a r e n t .

B u r w e l l ' s t h e o r y (a s o r i g i n a l l y r e p o r t e d byF i s c h e r , p p . 9 4 2 , 3 , 1937) on th e o r i g i n of a v a n adium d e p o s i t i s worthy of m e n t i o n :

He ( B u r w e l l ) b e l i e v e s t h a t t h e o re a t

R i f l e was f o r m e d a sa

d e l t a i c d e p o s i to f v a n a d i f e r o u s s a n d s and t h a t t h ec a r n o t i t e d e p o s i t s were f o r m e d by mea n d e r i n g , b r a i d e d s t r e a m s , t h e r i c h e s t( v a n a d i u m ) d e p o s i t s p r o b a b l y f o r m i n gi n t h e m a i n c h a n n e l s . T h e s e c h a n n e ld e p o s i t s , i n h i s o p i n i o n , r e p r e s e n tt h e d e p o s i t i o n of v a n a d i u m - and u ran iumr i c h m a t e r i a l s . The o r i g i n a l c o n c e n -

t r a t i o n of t h e m e t a l s o c cu r r ed e l s e w h e r eand h e r e c o g n i z e s t h a t t h e m a n n e r andform of t h i s c o n c e n t r a t i o n mus t be c o ns i d e r e d l a r g e l y h y p o t h e t i c a l .

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The n i n e d i f f e r e n t men who have i n v e s t i g a t e dor r ev i ewed t h e g e n e r a l o c c u r r e n c e of th e ores a tS i l v e r Ree f o f f e r tw o b a s i c t h e o r i e s of o r i g i n :

The d e p o s i t s a r e r e l a t e d t o i g n e o u s a ct i v i t y .

The d e p o s i t s a r e of s e d i m e n t a r y o r i g i n .

1 . The m e t a l s were c o n c e n t r a t e d a t t h et i m e o f d e p o s i t i o n .

2 . F i n e l y d i s s e m i n a t e d m i n e r a l p a r t i c l e sw e r e d i s s o l v e d and t h e m e t a l s l a t e rc o n c e n t r a t e d by m e t e o r i c w a t e r s .

S u m m a r i z i n g , R o t h w e l l , R o l k e r , and p o s s i b l yB a l l , f avo red an igneous o r i g i n whereas "C. F . A." ,Newber ry, L i n d g r e n , B u t l e r , C r a n e , and F i s c h e r ,p r o p o s e d a s e d i m e n t a r y o r i g i n f o r t h e d e p o s i t s .

A g e n e t i c r e l a t i onsh ip of th e ore s t o i gne ousa c t i v i t y h a s m et w i t h l i t t l e s u p p o r t and knownf a c t s do n o t seem t o s u p p o r t t h i s t h e o r y. The widea r e a l d i s t r i b u t i o n of t h e s i l v e r and v e r y s i m i l a rc o p p e r - v a n a d i u m - u r a n i u m d e p o s i t s of t h e C o l o r a d oP l a t e a u , t h e ex t r eme r a r i t y of a s s o c i a t e d i gneousr o c k s , t h e a b s e n c e of a l t e r a t i o n t y p i c a l l y f ou ndi n h y d r o t h e r m a l d e p o s i t s , t h e v e r y few o re m i n e ra l s - - n o n e of which i s a c e r t a i n hypogene m i n e r a l ,

t h e l a c k of t h e u s u a l t e x t u r e s ( L i n d g r e n , pp. 1 6 8 -1 9 0 , 1 9 3 3 ) found i n h y d r o t h e r m a l , e p i g e n e t i c d ep o s i t s , and t h e r a r i t y or comple te absence of f e e din g channe l s a l l seem t o i n d i c a t e t h a t th e d e p o s i t sa re n o t d i r e c t l y r e l a t e d t o igneous a c t i v i t y .

The s i m i l a r th e o r i e s of "C. F. A." , Newberry,and Crane f a i l t o e x p l a i n some m a j o r f e a t u r e s oft h e depos i t s . "C.F.A." proposed t h a t th e d e p o s i t i o n

of th e ore s was p e r f e c t l y con temporaneous wi th th ef o r m a t i o n of th e sands tone s t r a t a which would implya c o n t i n u i t y i n d e p t h f o r t h e o re d e p o s i t s . He

a l s o b e l i e v e d t h a t th e s i l v e r was o r i g i n a l l y p r ec i p i t a t e d as a c h l o r i d e or n a t i v e s i l v e r . Thef a i l u r e of th e ores t o c o n t i n u e i n d e p t h wi th th e

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same r i c h n e s s as t h o s e a t th e s u r f a c e , th e p r e s e n c eo f s u l f i d e s a t or n e a r th e w a t e r t a b l e , and d e c r e a s ei n th e s i l v e r ch lo r ide con t en t appea r s t o i n v a l i d a t eh i s c o n c e p t . Newberry ' s t h e o r y f a i l e d f o r th e samer e a s o n , a s i n c r e a s ing mining dep th b r o u g h t d e c r e a s i n g

m e t a l c o n t e n t . C r a n e ' s c o n c e p t d i f f e r s i n t h a t hes t a t e d t h a t t h e d e p o s i t s were formed u n d e r mar inec o n d i t i o n s and d e p o s i t e d as s u l f i d e s and p o s s i b l yn a t i v e s i l v e r . The c o n t i n e n t a l c h a r a c t e r i s t i c so f th e e n c l o s i n g S i l v e r Reef s a n d s t o n e i s c o n t r a r yt o C r a n e ' s c o n c e p t of m a r i n e d e p o s i t i o n . A l s o ,under normal marine c o n d i t i o n s c h l o r i d e i o n s wouldbe f a r i n e x c e s s of hydrogen s u l f i d e and th e s i l v e ri o n s c a r r i e d i n by th e s t r eams would be p r e c i p i t a t e d

as th e s i l v e r c h l o r i d e and n o t th e s u l f i d e . Howe v e r, l a g o o n a l c o nd i t i o ns might have p r e v a i l e d underC r a n e ' s t h e o r y and s u l f i d e d e p o s i t i o n m i g h t havebeen p o s s i b l e . B ut t h e t e r r e s t r i a l c h a r a c t e r ofth e s e d i m e n t s and t h e l a c k o f a r e a s o n a b l e e x p l a na t i o n f o r t h e o r i g i n of t h e m i n e r a l p a r t i c l e s orm i n e r a l - b e a r i n g w a t e r s l e a v e s much t o be e x p l a i n e di n h i s and th e o t h e r t h e o r i e s .

F i s c h e r ' s o r i g i n a l c o n c e p t f i t s many of t h eo b s e r v e d f i e l d f a c t s f o r t h e d e p o s i t s . Ye t , i fone c o n s i d e r s t h e v e r y d i l u t e s o l u t i o n s he i m p l i e s ,and t h e d e p o s i t i o n a l e n v i r o n m e n t which he p o s t ul a t e s . I t seems doub t fu l t h a t th e " a g e n t or a g e n t s "would be i n s u f f i c i e n t number, or more s i g n i f i c a n tl y t h e a d d i t i o n of d i l u t e m i n e r a l - b e a r i n g w a t e r st o t h e l a k e s g r e a t e n o u g h t o s u p p l y t h e n e e d e dm e t a l l i c c o n t e n t b e f o r e t h e n e x t f l o o d would sweep

t h r o u g h t h e a r e a and c a r r y t h e m i n e r a l p a r t i c l e saway. However, F i s c h e r a p p a r e n t l y h a s abandonedh i s o r i g i n a l c o n c e p t f o r he d o e s n o t m e n t i o n i t

i n h i s l a t e r p u b l i s h e d w o r k .

L i n d g r e n ' s and B u t l e r ' s c o n c e p t s p r e s e n t mucht h a t i s c o n s o n a n t wi th th e known f a c t s . N e i t h e r ,however, o f f e r e d any c o n c l u s i ve d a t a on th e o r i g i no f t h e m e t a l l i c p a r t i c l e s , and t h i s i s t h e g r e a t

d e f i c i e n c y i n t h e i r t h e o r y. The m i n e r a l p a r t i c l e st h e y s u g g e s t a re undoub ted ly p o s s i b l e , th e c i r c u l at i o n of ground w a t e r , e s p e c i a l l y i n p o r o u s s a n ds t o n e , a proven f a c t , and th e p o s s i b i l i t y of l e a c h -

- 127 -



in g and r e p r e c i p i t a t i o n a c e r t a i n t y as demons t ra tedi n many mining d i s t r i c t s of th e wes t .

The s t reams which supp l i ed th e supposed mine ra lp a r t i c l e s f r a n a c r y s t a l l i n e a r e a must have dra ineda v e r y b r o a d a r e a and f l owed a c o n s i d e r a b l e d i s -

t a n c e . The n e a r e s t s o u r c e t o t h e e a s t would haveb e e n i n C o l o r a d o , t o t h e s o u t h d e e p i n A r i z o n a ,w e s t , f a r i n t o Nevada , and n o r t h o v e r a hundredm i l e s , and probab ly more, f o r Tr i a s s i c rocks e a r l i e rt h a n C h i n l e c r o p out t h r o u g h much of t h e s e a r e a se v e n a t t h e p r e s e n t t i m e . The v e r y f i n e g r a i ns i z e ~ a n g i n gf rom 0 . 1 t o 0 . 1 5 mm. i n d i a m e t e r sl o c a l l y l a r g e r , s u g g e s t s t h a t on ly t h e s m a l l e s tof m e t a l l i c p a r t i c l e s , i f s u c h t r u l y e x i s t e d ,

could have been c a r r i e d by th e s t reams i n the mininga r e a . T h e i r t h e o r y when a p p l i e d t o o t h e r l i k e d e -p o s i t s a l s o r e q u i r e s a sou rce l a r g e enough n o t onlyt o have s u p p l i e d a t h i c k n e s s of s e v e r a l t h o u s a n d so f f e e t of r o c k o v e r h u n d r e d s of s q u a r e m i l e st h r o u g h t h e Upper P e r m i a n , p a r t of t h e T r i a s s i c ,and i n t o t h e l a t e J u r a s s i c , b u t a l s o a s u f f i c i e n tm e t a l l i c c o n t e n t of uran ium, vanad ium, coppe r, ands i l v e r f o r th e numerous d e p o s i t s of th e s o u t h w e s t .Why a l s o s h o u l d one o r tw o h o r i z o n s r e c e i v e t h eg r e a t e s t p o r t i o n of t h e s e m e t a l s , w h i l e r o c k s ofs i m i l a r l i t h o l o g y and c o m p o s i t i o n a d j a c e n t t o i t

a re b a r r e n , or n e a r l y so? F i n a l l y , t h e r a t h e r un-u s u a l f a c t t h a t t h r o u g h o u t t h e wor ld t h e s e samet y p e of d e p o s i t s o c c u r i n t h e same p e r i o d s makesi n t e r e s t i n g s p e c u l a t i o n a s t o a p o s ~ i b l eb r o a d e rc o n t r o l t h a n may have been o b t a i n e d i n some l o c a la r e a .

With such a v a r i a b i l i t y i n h y p o t h e s e s f o r th eo r i g i n of t h e S i l v e r Reef d e p o s i t s i t would bed i f f i c u l t indeed t o propose one which more c l o s e l yf i t t h e o b s e r v e d f a c t s w i t h o u t i n c l u d i n g much o ft h a t which has a l r e a d y been s u g g e s t e d . Since t h i ss t u d y i s c o n c e r n e d w i t h t h e S i l v e r Reef a r e a , i t

i s no t th e purpose of th e paper t o urge a new t heo ry

o f o r i g i n f o r t h e a d j a c e n t Colorado P l a t e a u d e p o s -i t s , b u t i n so f a r as p o s s i b l e t o e x p l a i n th e l o c a lc o n d i t i o n s . Many of t h e d a t a undoub ted ly w i l l f i t

i n t o t h e b r o a d e r p i c t u r e , pe rhaps o t h e r s w i l l n o t ,as l o c a l c o n d i t i o n s of d e p o s i t i o n must have v a r i e dc o n s i d e r a b l y d u r i n g T r i a s s i c and J u r a s s i c t i m e s .

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I n g e n e r a l , th e c o n c e p t s of L i n d g r e n , B u t l e rand F i s c h e r , i n p a r t , o f f e r a good b a s i s of d i sc u s s i o n , and i t i s b e l i e v e d t h a t a fe u m o d i f i c a t i o n sa more r e a s o n a b l e p i c t u r e o f t h e g e n e s i s may becon s i d e r e d .

A b r i e f r e v i e y of t h e knoyn m i n e r a l s i n t h ed e p o s i t l i s t e d i n Ta b l e 6 r e v e a l s t h e i m p o r t a n tf a c t t h a t none i s of undoub ted hypogene or p r imaryo r i g i n .

Table 6

"Ore" M i n e r a l s a t S i l v e r R e e f , Utah

S i l v e r s u l f i d eS i l v e r se l en ide (?)Native s i l v e rCerargyr i t eEmboli t e (? )

Gold

C h a l c o c i t eC h a l c o p y r i t eB o r n i t eC u p r i t eTe n o r i t eM a l a c h i t eA z u r i t e

C a r n o t i t eAutun i teVo l b o r t h i t e

Pyr i t eHemat i t eI ron Oxides

( Limonite?)

M i n e r a l s r e p o r t e d t o h a v e o c c u r r e d b e l o yy a t e r t a b l e i n c l u d e c h a l c o c i t e , p y r i t e , n a t i v es i l v e r , and s i l v e r s u l f i d e . Each of t h e s e m i n -e r a l s , so f a r as i s known, yas d i r e c t l y or c l o s e l ya s s o c i a t e d y i t h p l a n t r ema ins . Most g e n e r a l l y t heyo c c u r r e d i n decomposed yood or l i g n i t e - l i k e s u bs t a n c e . These m i n e r a l s , and p o s s i b l y c h a l c o p y r i t e

and b o r n i t e , r e p r e s e n t t h e o r i g i n a l m i n e r a l s i nt h e d e p o s i t b e f o r e o x i d a t i o n t o o k p l a c e .

I t i s n o t d i f f i c u l t t o p o s t U l a t e t h e p o s s i b l echemica l r e a c t i o n s y h i c h may have o c c u r ~ e dto ' formth e mine ra l s noy p r e s e n t i n th e d e p o s i t . As p y r i t ea p p e a r s t o be one of t h e e a r l i e s t o f s u l f i d e s yemay y r i t e a f a m i l i a r r e a c t i o n s u g g e s t e d f o r t h es o l u t i o n o f p y r i t e ( p . 1 5 9 , Emmons, 1 9 1 7 ) :

FeS 2 + 7 ° + H2 0 --?- F e S o 4 + H2 S0 42FeS0 4 + H2 S0 4 + ° ~ Fe 2 ( S0 4)3 + H2 0

- 129 -



I n t u r n t h e f e r r i c s u l f a t e c o u l d r e a c t ont h e c h a l c o c i t e i n t h e f o l l o w i n g p o s s i b l e manner :

Fe 2 (S04)3 + Cu 2 S ~ Cu S04 + 2 Fe S04

+ Cu S

Fe 2 (S04)3 + CuS + 3 ° + H2 0 ~ CUS0 4+2FeS0

4+ H

2S0

4

C h a l c o p y r i t e and b o r n i t e migh t a l s o be t a k e ni n t o s o l u t i o n when exposed t o c i r c u l a t i n g groundw a t e r c o n t a i n i n g oxygen:

CuFeS 2 + 80~

CuS0 4 + FeS0 4

CuS

FeS4

+ 2H 2 S04

+ 180 ~ 5CuS04

+ 2H 2 0

+ FeS04

I f s i l v e r s u l f i d e a l s o o c c u r r e d i n or n e a rt h e c h a l c oc i t e i t , t o o , woul d be d i s s o l ved . Cooke

( p . 9 , 1 9 1 3 ) a d d s t h a t al i t t l e

f e r r i c s u l f a t ei n s o l u t i o n wi"ll c o n s i d e r a b l y i n c r e a s e th e s o l u b i -l i t y of s i l v e r i n d i l u t e s u l f u r i c a c i d . He sugges t st h a t f e r r i c s u l f a t e p r o b a b l y o x i d i z e s any hydrogens u l f i d e t h a t i s formed, t hus removing i t from s o l u -t i o n so t h a t th e f u r t h e r s o l u t i o n of s i l v e r s u l f i d ei s n o t s u p p r e s s e d . Emmons ( p . 2 5 5 , 1917) n o t e st h a t th e i o n i z a t i o n c o n s t a n t ( n e g l e c t i n g a c t i v i t i e sof th e i ons ) i s :

Ag SO2 4

On th e b a s i s of th e above, an i n c r e a s e i n s u l -f a t e io n i n s o l u t i o n shou ld d e c r e a s e th e s i l v e r i ns o l u t i o n . A c t u a l l y t h e r e v e r s e o c c u r s . Cooke

(p . 1 6 , 1913) s u g g e s t s t h a t i n p a r t , an AgS0 4 io ni s fo rmed which i s n o t a f f e c t e d by t h e p r e s e n c eof th e S04 i o n . The fo l lowing r e a c t i o n i s p o s s i b l e :

Ag2 S + H2 S0 4~ Ag 2 S0 4 + H2 S

(Ag+ ) (AgS0'4

- 130 -



i n combina t ion with :

which q u i c k l y removes th e H 2 S formed and p r e v e n t sr e p r e c i p i t a t i o n of s i l v e r as s u l f i d e .

The o r i g i n a l uran ium-vanad ium m i n e r a l s whichoccur red i n th e d e p o s i t s a re no t known, nor i s t h es e l e n i u m c o m p o s i t i o n . Thus i t i s i m p o s s i b l e t op r e d i c t w h a t c h e m i c a l r e a c t i o n s may h a v e t a k e np l a c e t o form t h e m i n e r a l s f o u n d t o d a y . I t c a nbe s t a t e d t h a t they a re r e l a t e d , a t l e a s t s p a c i a l l y ,with p l a n t r ema ins , b u t th e mode of p r e c i p i t a t i o n i sunknown. However, a l l of th e e l e m e n t s e x c e p t u r a nium, vanadium, se len ium and phosphorous which makeup th e m i n e r a l s a r e abundant i n t h e e n c l o s i n g r ocksand a v a i l a b l e f o r c h e m i c a l r e a c t i o n . Even p h o sphorous i s p o s s i b l e from t h e c h e m i c a l breakdown ofsome of t h e a p a t i t e exposed on t h e q u a r t z g r a i n s ,b u t a more l o g i c a l source would be t h e p l a n t s thems e l v e s . Twenhofe l

(p .26 , 1932) n o t e s f rom S c h u ~

e t t e r s and Hoffman ' s work (p . 2 4 9 - 2 5 4 , 1927) t h a tsome a q u a t i c p l a n t s ana lyzed f rom Lake Mendota a tM a d i s o n , Wi s c o n s i n had a p h o s p h o r o u s c o n t e n t o f0.23% f o r Va l l i s n e r i a and 0.13% f o r P o t a m o g e t o n .Some of th e r u s h - l i k e and r e e d - l i k e p l a n t f o s s i l si n th e S i l v e r Reef s a n d s t o n e may w e l l have had a

p h o s p h o r o u s c o n t e n t which on d e c o m p o s i t i o n of th ep l a n t s would b e a v a i l a b l e f o r c h e m i c a l r e a c t i o nw i t h t h e o t h e r e l e m e n t s t o form t o r b e r n i t e anda u t u n n i t e . The p o s s i b l e s o u r c e o f t h e u r a n i u mv a n a d i u m and s e l e n i u m w i l l be d i s c u s s e d l a t e r .

The s o l u b l e s u l p h a t e s o f c o p p e r and s i l v e rwould be r e a d i l y p r e c i p i t a t e d u n d e r c e r t a i n chemi c a l c o n d i t i o n s d u r i n g t h e downward m i g r a t i o n ofth e s o l u t i o n s . F o r e x a m p l e ,

m i g h t be a l i k e l y r e a c t i o n , s i n c e s a l t i s knowni n beds above and below t h e S i l v e r R e e f s a n d s t o n eand could be r e a d i l y t aken i n t o s o l u t i o n and c a r r i e d

- 131 -



II

·

Ii i n t o th e ore h o r i z o n . The r e a s o n why s i l v e r c h l o -r i d e g e n e r a l l y p r e c i p i t a t e d i n t h e p r e s e n c e off o s s i l r e m a i n s i s n o t known, t h o u g h a d s o r p t i o non t h e f i n e l y d i v i d e d c a r b o n a c e o u s p a r t i c l e s mayhave been i m p o r t a n t .

Copper s u l p h a t e could r e a c t with ac id carbona tew a t e r s t o form m a l a c h i t e and a z u r i t e r e s p e c t i v e l y(Kemp, p . 2 4 , 1 9 0 6 ) :

2CuS0 4 + 2H2

Ca(C03

)2 -+ CuC03

• Cu(OH)2

+ 2CaS04

+ 3 C02

+ H2

0

3CuSo4 + 3H 2 Ca(C0 3 )2 -+ 2CuCO • CuCOH)2

From m i c r o s c o p i c e v i d e n c e i t i s known t h a tb o t h malach i t e and a z u r i t e l o c a l l y r ep laced c a l c i t 8cemen t . Emmons (p . 180 , 181 , 1917) s u g g e s t e d t h ef o l l o w i n g r e a c t i o n s f o r m a l a c h i t e and a z u r i t e r e -

s p e c t i v e l y :

2CuS04

+ 2CaC03

+ 5 H2

0 -+ cuC03

• CU(OH)2

+ 2CaS04

• 2H2 0 + CO

2

3 CUS04 + 3CaC03

+ 7H2 0 -+ 2CuC0 3 . Cu(OH)2

+ 3 Ca S0 4 . 2H 2 0 + CO2

G a r r e l ' s and S t i n e ' s r e c e n t e x p e r i m e n t a l work(pp . 21-30 , 1948) on th e r ep l acemen t of c a l c i t e byb a s i c c opper c h l o r i d e , and t h e i r " t e n t a t i v e " e x p e rimen t s wi th c o p p e r s u l p h a t e s o l u t i o n s and c a l c i t ea r e of i n t e r e s t . Accord ing t o them (p . 30 , 1948)i n t h e l a t t e r expe r imen t a " b a s i c coppe r s u l p h a t e( e x a c t form u n d e t e r m i n e d ) " formed a t t h e s u r f a c eof c a l c i t e r a t h e r t han ma lach i t e as would have beene x p e c t e d by Emmons' f o r m u l a . F u t u r e work a l o n gt h e s e l i n e s may w e l l change some of t h e now g e n e ra l l y p o s t u l a t e d c h e m i c a l r e a c t i o n s . However, th eg r e e n m i n e r a l a t S i l v e r Reef was i d e n t i f i e d asm a l a c h i t e .



The above r e a c t i o n s a r e on ly s u g g e s t i v e o ft hose which may have t aken p lace t o form th e s econd -a r y m i n e r a l s of t h e d e p o s i t s . The p r e s e n c e ofc h a l c o c i t e n o d u l e s i n t h e o x i d i z e d z o n e , many ofthem wi th a f i l m of m a l a c h i t e a round t hem, i m p l i e s

t h a t l o c a l l y r e d u c i n g c o n d i t i o n s may h a v e b e e nmore p o w e r f u l t h a n t h e o x i d i z i n g and a s a r e s u l tt h e c u p r o u s s u l f i d e d i d n o t g o i n t o s o l u t i o n .I n t e r e s t i n g l y e n o u g h , f o s s i l p l a n t r e m a i n s a r ea b u n d a n t a r o u n d or v e r y n e a r t h e s e c h a l c o c i t en o d u l e s , t h o u g h l o c a l l y l i m o n i t i c p s e u d o m o r p h sa f t e r p y r i t e may b e f o u n d w i t h t h e c o p p e r .

The s e c o n d a r y m i n e r a l s of t h e d e p o s i t a p p e a rt o have c o n c e n t r a t e d m a i n l y i n t h e c h a n n e l s of t h emos t p e r m e a b l e s a n d s t o n e s . These s a n d s t o n e s c o n -t a i n abundant openings as a r e s u l t of th e decompos i -t i o n of t h e p l a n t s and th e n a t u r a l molds which r e -

main . The s i l v e r c o n t e n t , of c o u r s e , i s n o t whol lyr e s t r i c t e d t o t h e s e c h a n n e l s , b u t a l m o s t a l l com-m e r c i a l d e p o s i t s were e i t h e r r e l a t e d t o them or t opermeab le b e d d i n g p l a n e s where molds a l s o remaineda f t e r th e d e c o m p o s i t i o n of p l a n t s which were d e p o s -i t e d on t h e s e p l a n e s . The argument might be o f f e r e dt h a t t h e l o c a l i z a t i o n was t h e r e s u l t of t h e p l a n t sand t h a t th e c h a n n e l s were s e c o n d a r y i n i m p o r t a n c e ,y e t , o u t s i d e t h e c h a n n e l s t h e r e a r e b u t few p l a n tf o s s i l s . T h u s , t h e tw o f e a t u r e s a r e d i r e c t l yr e l a t e d .

Though t h e above d i s c u s s i o n may a c c o u n t f o rt h e s e c o n d a r y m i n e r a l s of t h e d e p o s i t s , i t s t i l l

does n o t e x p l a i n t h e s o u r c e of t h e m i n e r a l s be lowt h e w a t e r t a b l e . The c l o s e r e l a t i o n s h i p of t h em i n e r a l s t o p l a n t f o s s i l s l e a d m o s t w r i t e r s t os u g g e s t t h a t t h e f o s s i l p l a n t s a c t e d a s r e d u c i n gagen t s and c o n v e r t e d s o l u b l e s u l p h a t e t o i n s o l u b l es u l f i d e s . B a s t i n (p . 424 , 1933) s u g g e s t s t h a t th ep l a n t s ' i n f l u e n c e , h o w e v e r, may be more l a r g e l yp h y s i c a l than c h e m i c a l and ment ions t h a t no e x p e r i -m e n t a l e v i d e n c e h as shown t h a t r e d u c t i o n s of s u l -p h a t e s t o s u l f i d e s c an p r o c e e d a t o r d i n a r y t e m p e r -a t u r e s . H is f i n a l s t a t e m e n t i s w o r t h y of n o t e :

- 133 -



S i n c e i t i s q u i t e p o s s i b l e t h a t f u r t h e re x p e r i m e n t a t i o n w i l l supply such ev idence ,i t would be h i g h l y i n c a u t i o u s a t p r e s e n t

t o summar i ly d i s m i s s t h e p o s s i b i l i t y ofd i r e c t r e d u c t i o n .

O t h e r f i e l d d a t a a re h i g h l y s u g g e s t i v e t h a tr e d u c t i o n s do o c c u r n e a r p l a n t s u b s t a n c e s . Thew r i t e r , with o t h e r s , has observed s m a l l carbonaceousremains i n red s h a l e s sur rounded by a gray or l i g h tg r e e n zone . S i m i l a r l y i n r e d s a n d s t o n e s , c a r b o n -aceous s u b s t a n c e s a r e e n c l o s e d by a b l e a c h e d zone

of w h i t e s a n d s t o n e which s u g g e s t s t h a t t h e f e r r i ci r o n has been r e d u c e d t o t h e more s o l u b l e f e r r o u sv a r i e t y and c a r r i e d away i n s o l u t i o n . Mason (Mason,B . H . , p e r s o n a l communicat ion) observed an i n t e r e s ti n g o c c u r r e n c e a t t h e Kawau Coppe r Mine i n New

Zealand . The mine had j u s t been opened a f t e r be ingc l o s e d f o r many y e a r s . Copper s u l p h a t e s o l u t i o n st r i c k l i n g down over decay ing mine t imbers appa ren t lyhad been reduced t o n a t i v e c o p p e r. He observed non a i l s n e a r b y which m i g h t h a v e p r e c i p i t a t e d t h em e t a l l i c c o p p e r . H i n t z e (p . 2 0 4 , 1904) r e c o r d sa s i m i l a r o c c u r r e n c e i n t h e Black Mine a t Chessy,F r a n c e . F u r t h e r , t h e o c c u r r e n c e of c o m m e r c i a ls i l v e r d e p o s i t s i n w h i t e t o l i g h t b u f f s a n d s t o n e ,wi th a s s o c i a t e d p l a n t r e m a i n s , a l l i n t e r b e d d e d i nr e d s h a l e s and s a n d s t o n e s u g g e s t s t h a t r e d u c i n gc o n d i t i o n s must have been e s s e n t i a l t o t h e p r e c ip i t a t i o n of t h e m i n e r a l s .

In a p r e s e n t a t i o n of a summary of t h i s p a p e rb e f o r e t h e Utah Academy of S c i e n c e of 1 9 5 0 , Mr.W. R. A n d e r s o n , c o n s u l t i n g g e o l o g i s t , r e p o r t e d( p e r s o n a l communica t ion) t h a t he had found n a t i v ec o p p e r on p i n e c o n e s and c h a l c o p y r i t e w i t h p l a n tr e m a i n s f rom Bingham Canyon, U t a h , a l l of r e c e n to r i g i n .

O t h e r p o s s i b i l i t i e s e x i s t . Hydrogen s u l f i d emay have b e e n g e n e r a t e d by t h e d e c o m p o s i t i o n oft h e p l a n t s or b a c t e r i a l a c t i o n a s s o c i a t e d w i t ht h e i r d e c a y and p r e c i p i t a t e d t h e s u l p h a t e s ass u l f i d e s . G e n e r a l l y , h y d r o g e n s u l f i d e r e s u l t sfrom s u l p h u r - b e a r i n g compounds i n a n i m a l r e m a i n s



a c c o r d i n g t o B a s t i n ( q u o t e d f rom S t a g n i t t a - B a l ls t r e r i : Die Ve r b r e i t u n g d e r S c h w e i f e l w a s s e r s t o f fb i l d u n g u n t e r d e n B a c t e r i e n . A r c h . f u r H y g i e n e ,Bd. 1 6 , 1 8 9 3 , 3 3 - 3 4 ) . Ye t , h e a l s o n o t e s t h a tp l a n t e x t r a c t s r i c h i n s u l p h u r - b e a r i n g p r o t e i n s :

y i e l d e d h y d r o g e n s u l f i d e when i n n o c ul a t e d w i t h t h e same t y p e s o f b a c t e r i at h a t y i e l d t h i s gas f rom a n i m a l e x t r a c t s

From t h e e x p e r i e n c e of t h e w r i t e r as w e l l ast h a t of o t h e r worke r s i n t h e d i s t r i c t , p l a n t s werep a r t l y decomposed or a l t e r e d f rom t h e i r o r i g i n a ls t a t e b e f o r e p r e c i p i t a t i o n of th e m e t a l l i c m i n e r a l s .This may no t be u n i v e r s a l l y t r u e as B u t l e r (p . 153 ,1920) and o t h e r s d esc r i be wood i n which th e c e l l u l a rs t r u c t u r e i s p r e s e r v e d i n copper ore r e p l a c i n g v e g -e t ab le mat t e r. The s o f t , ca rb onized wood and f l a k e sof s u l f i d e i n th e S i l v e r Reef a r e a would imply t h a tth e a t t e n d a n t c h e m i c a l changes du r ing d e c o m p o s i t i o nmay be an i m p o r t a n t f a c t o r i n p r o d u c i n g r e d u c i n g

c h e m i c a l c o n d i t i o n s . S i n c e 'most o r g a n i c m a t t e ra f t e r d e a t h i s b r o u g h t t o a more s t a b l e fo rm byt h e a c t i o n of b a c t e r i a , t h i s may i n d i c a t e t h a tt h e b a c t e r i a a r e e i t h e r d i r e c t l y or i n d i r e c t l yt h e t r u e c a u s e of t h e r e s u l t s above . Some i n t e re s t i n g o b s e r v a t i o n s and e x p e r i m e n t s were made byL o v e r i n g ( p . 4 5 , 1 9 2 8 ) , who n o t e d s p o n g y m a s s e sof c o p p e r i n :

b l a c k c l a y e y m a t e r i a l f u l l of o rg a n i c r emains . Blackened b l a d e s of g r a s s , p a r t l ydecomposed t w i g s and o t h e r m a t e r i a l s ofs i m i l a r n a t u r e a r e p l e n t i f u l .

He s u g g e s t s t h a t c u p r i c s u l p h a t e was r e d u c e dt o e l e m e n t a l c opper by t h e a c t ! on of o rg a n i c c ompounds , and by a s e r i e s of i n t e r e s t i n g e x p e r i m e n t s

was a b l e t o show t h a t i n d i r e c t l y t h e b a c t e r i a r educed t h e c o p p e r s u l p h a t e by means of t h e e x c r e t aproduced by t hem. Such a r e a c t i o n m i g h t p o s s i b l yapply t o th e n a t i v e s i l v e r , b u t i t would n o t e x p l a i nth e s u l f i d e s .

- 135 -



Z o B e l l ( p . 159, 166, 1946) summar i ze s muchof t h e i m p o r t a n t l i t e r a t u r e on t h e a c t i o n of b a ct e r i a on s u l f u r compounds. Though he d e a l s main ly

wi th marine b a c t e r i a , he does ment ion t h a t " s u l f a t er e d u c e r s " were i s o l a t e d from d i t c h w a t e r and a l s of r om s o i l . Z oBe l l a l s 0 p o i n t s out t h e i n t e r e s t i n gf a c t ( p . 166) t h a t s e l e n a t e i n t h e p r e s e n c e oforgan ic m a t t e r wi th oxygen exc luded may be reduced(p . 1 5 9 , 1946) by b a c t e r i a . His s t a t e m e n t t h a t :

The absence of f r e e oxygen, th e p r e s e n c eof s u l f a t e , and t h e p r e s e n c e of o rg a n i cm a t t e r a re th e c h i e f r equ i r emen t s f o r th ea c t i v i t y of s u l f a t e - r e d u c i n g b a c t e r i a .

i s ana logous t o c o n d i t i o n s which p r o b a b l y e x i s t e da t S i l v e r Reef .

The f a m i l i a r example of p y r i t e i n c o a l o f f e r ss u p p o r t t h a t s u l p h a t e s o l u t i o n s can be r educed t ot h e s u l f i d e s t a t e . The same m i g h t a p p l y i n t h ec a s e of b l a c k s h a l e s and a s s o c i a t e d p y r i t e , b u ta n i m a l l i f e may h a v e b e e n more i m p o r t a n t u n d e rt h e s e c o n d i t i o n s t h a n p l a n t , and any hydrogen s u lf i d e g e n e r a t e d by l i f e p r o c e s s e s or d e a t h c o u l dc a u s e p r e c i p i t a t i o n of t h e s u l f i d e . The o r i g i nof t h e c e l e b r a t e d K u p f e r s c h i e f e r of M a n s f i e l d ,

Germany b e a r s many a n a l o g i e s t o t h e a b o v e , andt h e a c t i o n of b a c t e r i a a s s o c i a t e d w i t h t h e decayof a n i m a l s and p l a n t s h as b e e n c i t e d f o r t h e s ed e p o s i t s (p . 415 , L i n d g r e n , 1 9 3 3 ) . Ye t , i t mustbe remembered t h e s e were formed unde r mar ine c o n -d i t i o n s , t h e S i l v e r Reef unde r c o n t i n e n t a l c o n d i -t i ons .

S i l v e r C h l o r i d e , n a t i v e s i l v e r , and l e s s

s i g n i f i c a n t l y t h e c o p p e r c a r b o n a t e s , a l s o o c c u rwi th c l a y g a l l s and c lay b a l l s i n c h a n n e l s . Threef a c t o r s may have been i m p o r t a n t i n t h i s l o c a l i z at i o n : ( 1 ) . The minera l s were adsorbed on th e l a rg eamount of s u r f a c e a r e a of th e c o l l o i d a l p a r t i c l e s ,( 2 ) . The r e d u c i n g a c t i o n of m a t e r i a l s p r e s e n t wi th



t h e s h a l e , s i n c e l i g h t green c l ay g a l l s a re r e p o r t e dt o have c a r r i e d much h i g h e r s i l v e r c o n t e n t t h an r edones , p r e c i p i t a t e d th e m i n e r a l s . (3 ) . The c h l o r i n eand c a r b o n a t e i o n s were a s s o c i a t e d w i t h t h e c l a y

g a l l s and c a u s e d p r e c i p i t a t i o n o f t h e m i n e r a l s .S i n c e b o t h n a t i v e s i l v e r and s i l v e r c h l o r i d e occurt o g e t h e r on t h e f r a c t u r e s u r f a c e s of t h e c l a y i t

i s s u g g e s t e d t h a t (1) and (2 ) were p r o b a b l y t h em o s t i m p o r t a n t f a c t o r s .

The p a r a g e n e t i c s e q u e n c e o f t h e m i n e r a l sc o u l d n o t be f u l l y d e t e r m i n e d f rom t h e s p e c i m e n sa v a i l a b l e . C e r t a i n l y , t h o u g h , one s e q u e n c e c o u l d

n o t be e x p e c t e d t o a p p l y over t h e e n t i r e d i s t r i c t .In one l o c a l i t y s o l u t i o n may have t ake n p l a c e whi lep r e c i p i t a t i o n was g o i n g on i n a n o t h e r . Va r i a t i o ni n t h e c o n c e n t r a t i o n s of t h e d i f f e r e n t s u b s t a n c e sc o u l d a l t e r t h e c o u r s e of t h e c h e m i c a l r e a c t i o n s .T h a t t h e s e v a r i a t i o n s d i d e x i s t i s shown by t h el i m o n i t e s t a i n s f rom d e c o m p o s i t i o n of p y r i t e i nsome l o c a l i t i e s and n o t i n o t h e r s , m a l a c h i t e i nabundance i n one p l a c e b u t a b s e n t i n o t h e r s , e t c .

However, a g e n e r a l s e q u e n c e i s i n d i c a t e d . P y r i t edoes appea r t o be an e a r l y m i n e r a l as i s c h a l c o c i t eand p oss i b l y s i l v e r s u l f i d e . The p o s i t i o n of b o r ni t e , c h a l c o p y r i t e , and t h e o r i g i n a l m i n e r a l s ofu r a n i u m - v a n a d i u m i s n o t known. I t i s a p p a r e n tf rom t h e n a t u r e of t h e m i n e r a l s t h a t t h e c a r b o n -a t e s of copper, c h l o r i d e of s i l v e r , and th e uraniumvanadium m i n e r a l s a re c l e a r l y th e secondary p r o d u c t sof o r i g i n a l s u l f i d e s and o t h e r m i n e r a l s u b s t a n c e s .

Whether s i l v e r c h l o r i d e was a lways l a t e r t h a n th ec a r n o t i t e cannot be s a i d , though i n th e few s e c t i o n ss tud i ed t h i s was t r u e .

The wide a r e a l d i s t r i b u t i o n of s i l v e r i n th eS i l v e r Reef s a n d s t o n e and i n some of th e s a n d s t o n e sand s h a l e s b o t h above and below t h e member i s s u gg e s t i v e of e i t h e r a w i d e s p r e a d s o u r c e or a v e r yr i c h o r i g i n a l s o u r c e o f s o l u t i o n s o r m i n e r a l

p a r t i c l e s . Tha t s o l u t i o n s d id c a r r y t h e compoundsi s v e r i f i e d by t h e o c c u r r e n c e s of th e m i n e r a l s b e -low th e ground w a t e r l e v e l as s u i f i d e r e p l a cem e n t sand f i l l i n g of c a r b o n a c e o u s s u b s t a n c e s . This c o nd i t i o n s u g g e s t s t h a t t h e ca rbonaceous m a t e r i a l must

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have r e c e i v e d i t s m i n e r a l c o n t e n t a f t e r i t s b u r i a lor j u s t f o l l o w i n g i t s d e p o s i t i o n . I t seems impos-s i b l e t o assume t h a t th e l i v i n g p l a n t had accumu-

l a t e d such a m e t a l c o n t e n t , e s p e c i a l l y as f o s s i lf r a g m e n t s of t r e e s s e v e r a l f e e t l o n g were i n s e ve r a l i n s t a n c e s ex t r eme ly r i c h i n s i l v e r . The r e a lproblem i s n o t t h e r e p l a c e m e n t or s u b s t i t u t i o n o ~

t h e p l a n t t i s s u e s f o r t h i s can be observed , bu t t hes o u r c e of t h e m e t a l l i c c o n t e n t of t h e s o l u t i o n s .

Perhaps g e o l o g i s t s have sea rched to o long f o rsome v e i n or i g n e o u s s o u r c e beyond t h e broad T r i

a s s i c b a s i n of d e p o s i t i o n . The p o s s i b i l i t y e x i s t st h a t a source or s o u r c e s w i t h i n th e b a s i n may havebeen over looked . C e r t a i n f e a t u r e s of th e sed imentsu n d e r l y i n g th e S i l v e r Reef s a n d s t o n e a r e a t l e a s ts u g g e s t i v e .

Numerous c o n c r e t i o n s - l i k e n o d u l e s of s i l v e rg o l d - b e a r i n g c h a l c o c i t e an d p y r i t e o c c u r i n ab e n t o n i t i c s h a l e 310 f e e t s t r a t i g r a p h i c a l l y belowt h e S i l v e r Reef s a n d s t o n e . These m i n e r a l s a r eknown t o o c c u r i n t h e b e n t o n i t i c s h a l e over manym i l e s . I n t h e A. S. & R. s h a f t a s s a y s of t h i sbed showed 0 . 4 5 o z . / t o n i n s i l v e r . T h i s m i g h tr a i s e t h e q u e r y as t o w h e t h e r such a h o r i z o n ast h i s or s i m i l a r o n e s , p a r t l y of d i r e c t v o l c a n i co r i g i n , m i g h t be a b l e t o s u p p l y t h e n e c e s s a r ym e t a l s f o r s u c h a d i s t r i c t as t h e S i l v e r R e e f .Or i s t h e occu r r ence only an odd i ty and n o t l i k e l yt o b e p r e s e n t e l s e w h e r e ? R. S. Cannon ( p e r s o n a lcommunica t ion , S e p t . , 1948) of th e U. S. G e o l o g i c a lSurvey r e f e r r e d th e w r i t e r t o some l i t e r a t u r e whichi n d i c a t e d t h a t o t h e r s had r e c o g n i z e d s o m e w h a ta n a l a g o u s o c c u r r e n c e s .

Lawson ( p . 4 4 4 , 1913) r e c o r d s t h e p r e s e n c eof m i n u t e amounts of go ld i n C h i n l e s h a l e s . H is

d e s c r i p t i o n of t h e s h a l e p r o p e r t i e s t a l l i e s w e l lf o r a b e n t o n i t e - l i k e s h a l e .

One of t h e m os t s t r i k i n g p r o p e r t i e s oft h e Sh ina rump (now C h i n l e ) c l a y i s i t s

b e h a v i o r i n w a t e r . Samples of t h e c l a yt a k e n i n th e f i e l d a r e u s u a l l y m o i s t and



t h e amount of w a t e r which may be d r i v e no f f a t l05°C i s v e r y c o n s i d e r a b l e . B utwhen a f r a g m e n t of t h e c l a y i s immersedi n wate r i t immed ia t e ly s w e l l s e n o r m o u sl y and b r e a k s down r a p i d l y i n t o an i n c o

h e r e n t f l a t cone • • • . The s w o l l e n c l a y oft h i s s u r f a c e l a y e r d r i e s ou t and becomesa l o o s e , f l u f f y pulp of ext reme l i g h t n e s s ,s o f t n e s s and in c oherence .

C. L a u s e n (pp . 610-617 , 1936) n o t e d m i n u t eq u a n t i t i e s of m e r c u r y i n t h e C h i n l e s h a l e s n e a rt h e l o c a l i t y of L a w s o n ' s r e p o r t . I t was f i r s t

r e c o g n i z e d when e f f o r t s t o r e c o v e r g o l d f rom th es h a l e s by amalgamat ion r e s u l t e d i n a g r e a t e r amountof mercury b e i n g r e c o v e r e d t han t he o r i g i n a l amountused . Lausen ment ions t h a t t h e s h a l e s a re b e n t o ni t i c bu t c a n n o t r e l a t e them d i r e c t l y t o v u l c a n i s m .

Touwaide ( p p . 1 4 0 - 1 , 1930) a l s o r e c o r d s ani n t e r e s t i n g occur rence of c o p p e r i n f o u r c l a y bedsi n t e r s t r a t i f i e d wi th v o l c a n i c t u f f s . He s u g g e s t st h a t t h e c o p p e r was e x t r a c t e d from t h e pyroxenesof t h e t u f f by c o n n a t e w a t e r s and l a t e r p r e c i p it a t e d , p o s s i b l y by "hydrogen s u l f i d e or some o t h e rcompound d e r i v e d f rom t h e organ i c m a t t e r i n c l u d e di n th e c l a y. " S i l v e r a l s o occurred i n t h i s d e p o s i t .

More r e c e n t l y , K o e b e r l i n (pp . 458-461 , 1938)i n a d i s c u s s i o n of F i s c h e r ' s ( p p . 609-651 , 1937)p a p e r b r i n g s o u t some i m p o r t a n t p o i n t s . B a s i n gh i s c o n c e p t on Emmon's t h e o r y of m i n e r a l - b e a r i n g

f l u i d s " c o l l e c t i n g i n t h e u p w a r d b u l g e s " o r" c u p o l a s " of b a t h o l i t h s , he s u g g e s t s t h a t i f th erock cover i s f r a c t u r e d or permeab le , th e "magmatice x t r a c t " may form v e i n s and l o d e s . The c r u x ofh i s d i s c u s s i o n i s :

But Emmons does n o t s t r e s s t h e f a c t t h a tth e co mbina t i on o f a c u p o l a w i th a s u i tab ly f r a c t u r e d r o c k c o v e r i s a f t e r a l l a

v e r y f o r t u i t o u s c i r c u m s t a n c e and t h a t af a r g r e a t e r p a r t of t h e magmat i c m i n e ra l i z e d f l u i d c o l l e c t i n g u n d e r t h e r o o fof th e b a t h o l i t h would probab ly be e j e c t e d

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MnO

VCoNiSe

Tab le 7

Minor C o n s t i t u e n t s of Tuff*Ly s i t e , Wyoming

(C. S. G i l b e r t , A n a l y s t )

Bed 2 Bed 350 .0 ppm 0 . 0 ppm

1 0 0 . 0 ppm 0 . 0 ppm5 .0 ppm 1 0 . 0 ppm6.3 ppm 29.4 ppm

1 8 7 . 0 ppm 1 7 5 . 0 ppm

* Table from Bea th , Hagner, and G i l b e r t , B u l l .

Geol . S u r v. of Wyoming.

36,

As shown by t h i s a n a l y s i s , n o t o n l y i s t h es e l e n i u m c o n t e n t of s i g n i f i c a n c e , b u t t h e o t h e rm e t a l l i c e l e m e n t s a re i n such amounts as t o m e r i tcomment . Comple te s o l u t i o n of t h e vanad ium andt h e se lenium con ten t would y i e l d s u f f i c i e n t q u a n t i t yof t h e e l e m e n t s t o m e r i t s e r i o u s t h o u g h t t o s ucht u f f s or s i m i l a r t u f f s b e i n g p r i m a r y s o u r c e s f o r

t h e s e and o t h e r e l e m e n t s . How much of th e vanadiumi s " a v a i l a b l e " f o r s o l u t i o n i s n o t known, b u t t h ea u t h o r s r e p o r t t h a t 96% of t h e s e l e n i u m i s w a t e rs o l u b l e . The known o c c u r r e n c e of s e l e n i u m w i t ht h e vanad ium-uran ium ore s of t h e C o l o r a d o P l a t e a uand a l s o w i t h t h e s i l v e r d e p o s i t s a t S i l v e r Reefwi th an a s s o c i a t e d vanad ium-u r an ium m i n e r a l i s ofn o t a b l e i n t e r e s t .

Summary

The o c c u r r e n c e of s e c o n d a r y " o r e " m i n e r a l si n t h e S i l v e r Reef s a n d s t o n e i s assumed t o be t h er e s u l t o f : ( a ) S o l u t i o n of f o r m e r o re m i n e r a l sd e p o s i t e d a s r e p l a c e m e n t s of p l a n t m a t e r i a l andas p r o b a b l e m i n e r a l p a r t i c l e s i n t h e s a n d s t o n e ,(b) R e p r e c i p i t a t i o n as new compounds p a r t l y f i l l i n gn a t u r a l molds l e f t by decomposing p l a n t s u b s t a n c e s

and as r e p l a c e m e n t of b o t h m a c r o s c o p i c and m i c r os c o p i c ca rbonac e o u s s u b s t a n c e s l o c a l i z e d a long th ebedd ing p l a n e s and i n T r i a s s i c s t r e a m c h a n n e l s i nth e S i l v e r Reef s a n d s t o n e .

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The a b s e n c e of a s s o c i a t e d i n t r u s i v e r o c k s ;wide a r e a l d i s t r i b u t i o n of t h e d e p o s i t s ; and th el a c k of s i l i c i f i c a t i o n , s e r i c i t i z a t i o n , t y p i c a lore t e x t u r e s , and o t h e r f e a t u r e s c o n s i d e r e d d i s -

t i n c t i v e of hypogene d e p o s i t i o n , s t r o n g l y s u g g e s t st h a t th e o r i g i n a l m i n e r a l s of th e d e p o s i t s d id no thave a hypogene o r i g i n .

F i n a l l y th e occu r r ence of s i l v e r , c o p p e r, andg o l d i n a b e n t o n i t i c s h a l e be low t h e S i l v e r Reefs a n d s t o n e , and ev idence i n o t h e r l o c a l i t i e s i n th es o u t h w e s t of s i m i l a r occu r r ences of m e t a l s i n con -c e n t r a t i o n s i n exces s of t h o s e i n ave rage v o l c a n i cr o c k s l e a d s t h e au t h o r t o p r op os e t h e f o l l o w i n gt h e o r y of o r i g i n :

The S i l v e r Reef meta l s were probab ly d i s s o l v e dmain ly as s u l p h a t e s or eroded away as a c t u a l minutem i n e r a l p a r t i c l e s , or b o t h , from T r i a s s i c v o l c a n i ct u f f s , now a l t e r e d t o b e n t o n i t e s , and t h e m e t a l st r a n s p o r t e d t o th e a r e a of th e mining d i s t r i c t byT r i a s s i c s t r eams and underground w a t e r s . Here th ecompounds i n s o l u t i o n were p r e c i p i t a t e d by decay ingp l a n t s or a s s o c i a t e d b a c t e r i a and t h e m i n e r a l p a r -t i c l e s were d e p o s i t e d as d e t r i t a l g r a i n s . The e v i -dence s u g g e s t s t h a t m o s t of t h e d i s s o l v e d m e t a l swere d e p o s i t e d as s u l f i d e s from s u l p h a t e s o l u t i o n su n d e r s t r o n g r e d u c i n g c o n d i t i o n s b r o u g h t a b o u te i t h e r b y : (1 ) g e n e r a t i o n of h y d r o g e n s u l p h i d et h r o u g h b a c t e r i a l a c t i o n on t h e v e g e t a t i o n or (2)t h e d i r e c t or i n d i r e c t a c t i o n of s u l p h a t e

r e d u c i n gb a c t e r i a a s s o c i a t e d w i t h t h e p l a n t r e m a i n s . Insome p l a c e s a d s o r p t i o n on c l a y g a l l s or on f i n e l yd i v i d e d c a r b o n a c e o u s p a r t i c l e s may have been im -p o r t a n t i n l o c a l i z i n g t h e m i n e r a l s . The knownp a r t i a l p a r a g e n e t i c sequence s u g g e s t s t h a t p y r i t ewas one of t h e f i r s t m i n e r a l s t o p r e c i p i t a t e f roms o l u t i o n and t h a t i t l a t e r may have ac t ed as a p r e -c i p i t a n t of c h a l c o c i t e and o t h e r s u l f i d e m i n e r a l s .

With u p l i f t and e r o s i o n of th e a r e a th e c i r c u l a t i o nof g r o u n d w a t e r b r o u g h t a b o u t t h e o x i d a t i o n ofp y r i t e and s o l u t i o n of many of t h e o t h e r s u l f i d e s .These were c a r r i e d downward and by a p r o c e s s ofs e c o n d a r y e n r i c h m e n t t h e p r e s e n t d e p o s i t s w e r ef o r m e d .

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THE MINES

Most of t h e i m p o r t a n t mines i n t h e d i s t r i c twere under company management dur ing th e produc t ivep e r i o d of t h e camp. Many of them were i n t e r c o n -

n e c t e d and p r o d u c t i o n came f rom a g r o u p r a t h e rt h a n a s i n g l e m i n e . A l l of them were s h a l l o w,t h e d e e p e s t e x t e n d i n g a p p r o x i m a t e l y 330 f e e t b e -low t h e s u r f a c e . Wate r p r e s e n t e d no prob l em i nt h e mines on t h e Whi te R e e f , b u t a l l m i n es j u s tn o r t h of th e C a l i f o r n i a and t o th e sou th a long th eBuckeye Reef had t o be pumped c o n t i n u a l l y . At th ep r e s e n t t ime a l l of t h e mines on t h e Buckeye Reefsou th of t h e Hartman s h a f t a re f l o o d e d .

On t h e b a s i s of p r o d u c t i o n and a r e a l d i s t r i -b u t i o n t h e m i n e s a r e r e a d i l y d i v i d e d i n t o s i xm a i n g r o u p s :

1 . The Thompson-Cobb a r e a i n c l u d i n g t h e SouthThompson, Thompson, Cobb, Newton, N i c h o l s ,and McNally mines .

2 . The C a l i f o r n i a - K i n n e r group which i n c l u d e st h e C a l i f o r n i a , Maggie , Las t Chance , S a vage , Buckeye , and Kinner mines .

3. Tecumseh H i l l a r e a wi th t h e S i l v e r F l a t ,Tecumseh, Stormy King, and Manhat ton minesi n c l u d e d .

4 . The Leeds and Leeds N o . 2 mines .

5. The Barbee and Walker a r e a .

6. The E a s t Reef group i n c l u d i n g th e Va n d e rb i l t , To q u e r v i l l e , D u f f i n , B r i s s a c h e r ,an d Maud m i n e s .

Thompson-Cobb a r e a . - The Thompson-Cobb a r e ai s p e n e t r a t e d by a t l e a s t 4000 f e e t of w o r k i n g s ,

n o t i n c l u d i n g s t o p e s . Each mine i s r e a c h e d by ana d i t a l o n g t h e b a c k s l o p e of t h e White R e e f . Att h e Thompson mine a caved a d i t 200 f e e t l o n g e xt e n d s from th e f a c e of th e White Reef t h rough t h e

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u n d e r l y i n g s h a l e s and i n t o th e ore h o r i z o n of th eS i l v e r Reef s a n d s t o n e . From t h i s a d i t an i n c l i n ec o n t i n u e s down t h e d i p a p p r o x i m a t e l y 160 f e e t .F i g u r e 11 shows t h e g e n e r a l r e l a t i o n s h i p of t h eworkings of t h i s mine and th e o t h e r s of th e group .

A ll of th e openings a re i n e x c e l l e n t c o n d i t i o nand have h e l d open w i t h l i t t l e or no t i m b e r overa l ong p e r i o d of t i m e . The m a j o r i t y of them a r ew i t h i n a few t e n s of f e e t of th e s u r f a c e wi th th ee x c e p t i o n o f t h e Cobb i n c l i n e and l o w e r d r i f t .The i n c l i n e p a r a l l e ~t h e 30 d e g r e e d i p of t h eo re bed f o r 500 f e e t . At 210 f e e t on t h e i n c l i n ea d r i f t t o th e n o r t h c o n n e c t s t o th e Nicho l s minet h rough a r a i s e . Thi s l e v e l i s f l o o d e d .

At l e a s t two aqd p o s s i b l y t h r e e s i l v e r p r od u c i n g h o r i z o n s o c c u r i n t h e Thompson-Cobb a r e a8-10 f e e t and 40' f e e t r e s p e c t i v e l y below th e Tecumseh s a n d s t o n e c o n t a c t . The s i l v e r ore occur s i nl e n s e s of w h i t e , f i n e - g r a i n e d s a n d s t o n e a s s o c i a t e dwith g r e e n i s h c l a y g a l l s and b a l l s , and appea r s t obe l i m i t e d t o t h e wid th of th e i n d i v i d u a l l e n s e s .The o re l e n s e s p i n c h s h a r p l y a l o n g t h e s t r i k e .

A s h e a r e d s h a l e h o r i z o n i n th e N i c h o l s minei s r e p o r t e d t o have c o n t a i n e d h i g h - g r a d e s i l v e rore as c o a t i n g s a l o n g t h e s h e a r p l a n e s . Copperc a r b o n a t e m i n e r a l s a r e l o c a l l y a b u n d a n t i n someof th e mines , e s p e c i a l l y i n t h e Nevton, Cobb, andS o u t h Thompson. The o re b o d i e s mined t h u s f a r

were as much a s 280 f e e t i n l e n g t h and 120 f e e ti n v i d t h , b u t m i n e a b l e o re i s s t i l l p r e s e n t i nt h e f a c e s of many of t h e s t o p e s i n t h i s group ofm i n e s .

Leeds and Leeds No. 2 mines . - The Leeds mineand t o a l e s s e r e x t e n t t h e Leeds N o . 2 mine ( s e ef i g u r e 12) produced a c o n s i d e r a b l e t onnage of ored u r i n g t h e e a r l y h i s t o r y of t h e d i s t r i c t . The

Leeds No. 2 mine h a s a b o u t 300 f e e t of v o r k i n g sand i s r e a c h e d by t v o s h a f t s i n t h e f l a t v e s t ofth e A. S. & R. s h a f t . Colba th ( p e r s o n a l communicat i o n ) r e p o r t s t h a t i t h as b e e n c o n n e c t e d t o t h eLeeds mine t o t h e n o r t h , b u t t h e s e work ings v e r en o t a c c e s s i b l e n o r v e r a t h e maps.

- 144 -



,T.4/S·1 R . /4 W

,I

T.415., R./3W.

- - - - - - - ----sEG:,-S- - - - -

III

S C E I ~________________ £0.1_7_I

F i g u r e 9 .in th e

Scale

00 0 2 4 0 0 3200 4 0 0 0

Pa ten ted c l a i m s (1948)Leeds , Utah , a r e a .

145



U.S.M.M. N o . 2 0

T. 41 5. , R. 13 W.

SEC·I /9

I

I j ~

__________ S E C · I ~1 _______ _

S C A L Eo 4 0 0 8 0 0 1600 t . c (

! I

F i g u r e 1 0 . P a t e n t e d c l a i m s (1948) i n th e E a s t Reefa r e a , s o u t h e a s t of Leeds , Utah .

- 146 -



In t h e Leeds No. 2 mine t h e o re s i m i l a r i ng rade t o t h a t i n th e main Leeds mine , o c c u r r e d i na w h i t e , f i n e - g r a i n e d s a n d s t o n e w i t h i n t h e Leedss a n d s t o n e . A g r e e n s h a l e h o r i z o n s e v e r a l f e e tt h i c k c u t o u t much of t h e o re b ed i n t h i s m i n e .

The s t o p e s of th e Leeds m i n e , 430 f e e t n o r t hof th e Leeds No. 2 mine , a re r e ach e d by a 150 f o o ta d i t a t t h e b a s e of t h e Whi te R e e f on t h e w e s t ,and a 2 - c o m p a r t m e n t s h a f t on t h e f l a t . Ore wass t o p e d f rom t h e t h r e e u p p e r l e v e l s . Two o t h e rl e v e l s were d r i v e n a t g r e a t e r d e p t h and a r e c o nn e c t e d by an i n c l i n e which s l o p e s 30 d e g r e e s wi th

t h e b e d d i n g . Most o f t h e u n d e r g r o u n d o p e n i n g sa r e s t i l l a c c e s s i b l e . The s u r f a c e s t o p e whichwas opened up from t h e u p p e r two l e v e l s a v e r a g e s300 f e e t l o n g and 150 f e e t w i d e .

Three ore zones were mined , and where t h e s ezones c o a l e s c e d th e s t o p e s were more t h a n 10 f e e th i g h . The s i l v e r minera l s occurred i n a b u f f , f i n egra ined , f i n e l y c ros s - l amina t ed sands tone c o n t a i n i n gm a l a c h i t e

and a z u r i t e i nt h e

Leeds s a n d s t o n e andr anged from 25 t o 30 f e e t below th e Tecumseh s a n ds tone c o n t a c t .

B a r b e e and Walker a r e a . - The H ones t M i n e rand Barbe e and Walker m i n e s make up t h i s g r o u p .The Hones t Miner mine i s 1150 f e e t n o r t h - n o r t h e a s tof t h e Leeds mine on t h e b a c k - s l o p e of t h e WhiteR e e f . On t h e w e s t a s h a f t 97 f e e t d e e p c o n n e c t s

wi th a n o t h e r s h a f t 110 f e e t e a s t t h r o u g ha

s t o p ewhich i s 10 -1 3 f e e t w i d e . P r o d u c t i o n v a l u e d a ta few t hous a n d d o l l a r s i s r e c o r d e d from a w h i t e ,f i n e - g r a i n e d s a n d s t o n e c o n t a i n i n g r e p l a c e m e n t sof p l a n t s by m a l a c h i t e .

The B a rbe e and Walker mine i n c l i n e i s 2050f e e t n o r t h - n o r t h e a s t of t h e H o n e s t Miner s h a f t .Only a p a r t of t h e m i n e i s a c c e s s i b l e by a 30

d e g r e e i n c l i n e i n t h e p l a n e o f b e d d i n g on t h ee a s t f a c e o f t h e W h i t e R e e f . The l o w e r l e v e l sa r e caved and i n a c c e s s i b l e . As f a r a s i s knownw a t e r was n o t a p r o b l e m i n t h e d e e p e r w o r k i n g sd u r i n g t h e p r o d u c t i v e p e r i o d of t h e m i n e . The

- 147 -



s i l v e r minera l s a p p a r e n t l y were f i n e l y d i s s e m i n a t e di n a 3-4 f o o t bed of b u f f t o whi t e f i n e l y : laminatedf i n e - g r a i n e d s a n d s t o n e . A p r o d u c t i o n of a l m o s ta m i l l i o n d o l l a r s i s recorded by th e o r i g i n a l Barbee

and Walker company.

Emi ly J a n e - S t o r m o n t a r e a . - The Stormont andEmily Jane mines have many s i m i l a r c h a r a c t e r i s t i c s .They l i e a t t h e sou th end of th e Buckeye Reef , th eo re o c c u r s i n a l i k e p o s i t i o n i n b o t h m i n e s , andt h e l i t h o l o g y and m i n e r a l o g y of t h e o re h o r i z o ni s p r a c t i c a l l y t h e s a me .

No maps were a v a i l a b l eMost of th e workings are caved or f i l l e d with wate r.Water i s r e p o r t e d t o have p layed an i m p o r t a n t p a r ti n th e c l o s i n g of t h e mine when major min ing ope rat i o n s c e a s e d i n 1 8 7 9 , b u t l e s s e e s or " c h l o r i d e r s "p r o b a b l y m i n e d i n t h e w o r k i n g s a t a l a t e r d a t e .

The o re h o r i z o n r a n g e d f rom a l m o s t n o t h i n gt o f i v e f e e t i n t h i c k n e s s and t h e s i l v e r m i n e r a l soccu r r ed i n a f i n e - g r a i n e d , whi t e t o gray sands tonej u s t below th e c o n t a c t of t h e Tecumseh-Leeds s a n ds t o n e s . The ore r a n as much as 100 ounces p e r t o n ,b u t t h e a v e r a g e p r o b a b l y d i d n o t exceed t h e 20-25ounce ave rage of th e camp. Near th e Farm Land gapa t t h e s o u t h end o f t h e Buckeye Reef s e v e r a l i nc l i n e s open i n t o c a v e d s t o p e s a l o n g t h e b e d d i n gi n l a v e n d e r s a n d s t o n e 12 f e e t a b o v e t h e b a s a lTecumseh. The work ings a re a lmos t comple t e ly cavedprobab ly as a r e s u l t of th e abundan t s h e a r i n g whichc u t s th e bedding a t an a c u t e a n g l e . Copper c a r b o na t e m i n e r a l s r e p l a c e f o s s i l p l a n t s a t t h e c o n t a c tof t h e L e eds and Tecumseh s a n d s t o n e s j u s t s o u t hof t h e abov e i n c l i n e s .

C a l i f o r n i a - K i n n e r Group. - This group of mineson t h e Buckeye Ree f i n c l u d e s some of t h e most im

p o r t a n t f o r m e r p r o d u c e r s i n t h e d i s t r i c t . F i g u r e12 shows more t han 20,000 f e e t of workings e x c l u s i v eof s t opes. The maj or p a r t of them i s f l ooded a t th ep r e s e n t t ime and i s , of c o u r s e , i n a c c e s s i b l e . Dataon t h e s e m in e s were o b t a i n e d from d i s c u s s i o n wi thf o rmer owners and o p e r a t o r s : Colba th , H a r t l e y , andNewman and from old mine maps.





-

LEEDS

~No.2

AsaRSHAFT

ELEVATION3878 '

?

0{[)IZl

•0

200

J(

EX P LA N A T I ON

Surface s t opeUnderground work ings

Shaf t

Roise

Winze

S cole

4pO 8 0 0 ~ o o FeelI

F i g u r e 1 2 . Known u n d e rg r o u n d work ings i n t h eL e e d s - C a 1 i f o r n i a - S a v a g e mine a r e a .

0



A ll of th e underg round work ings a re i n t e r c o nnec ted from th e C a l i f o r n i a mine on th e sou th t o th eKinner on th e n o r t h . The C a l i f o r n i a mine was d eve loped by f i v e l e v e l s . Whereas t o th e n o r t h 1700f e e t , a t th e Savage Mine, o re was p r o d u c e d from 7

l e v e l s .

The d e e p e s t w o r k i n g s p r o b a b l y o c c u r i n t h eo ld Maggie mine a t a d e p t h o f 330 f e e t be low t h es u r f a c e . At t h i s mine shr inkage s topes were c a r r i e dt o t h e f a c e of t h e Buckeye R e e f . Nor th o f t h e s es t o p e s t h e e a s t w a r d e x t e n t o f t h e u n d e r g r o u n dw o r k i n g s a p p e a r s t o h a v e s t o p p e d a t a s h e a r zonet r e n d i n g N. 1 0 - 3 0 E. The mine w o r k i n g s on t h i s

s e c t i o n of t h e Buckeye Reef a r e c o n n e c t e d t o t h eA. S. & R. s h a f t th rough an i n c l i n e from th e Savages t ope t o t h e 460 c r os s - c u t of t h e s h a f t . As f a ras i s known, th e underground workings , though f l o o ded , have h e l d op'en w i t h t h e e x c e p t i o n o f p a r t oft h e C a l i f o r n i a mine which c aved a f t e r t h e w a t e rwas pumped f rom i t i n 1 9 2 9 . Water was s t r u c k a ta s h a l l o w d e p t h i n t h e C a l i f o r n i a mine and a l s owas r e a c h e d t o some e x t e n t i n t h e Maggie d u r i n g

t h e e a r l y o p e r a t i o n s of t h e m i n e s .

The o re b e d s occu r w i t h i n a few f e e t e i t h e rs i d e of th e c o n t a c t of th e Tecumseh-Leeds s ands tone .The t h i c k n e s s of t h e ore zones r a n g e d from a fewi n ches t o s e v e r a l f e e t . L o c a l l y, a s i n th e Buckeyeand L a s t Change M i n e s , c o a l e s c e n c e on t h e d i p oftwo or more o re h o r i z o n s r e s u l t e d i n an ore zone20 or more f e e t i n t h i c k n e s s . Both t h e n e a r s u r

f a c e s t o p e s and dumps i n d i c a t e t h a t t h e s i l v e roccur red i n a w h i t e t o l a v e n d e r f i n e - g r a i n e d s a n ds t o n e , which c o n t a i n e d p l a n t i m p r e s s i o n s t h r o u g ho u t t h e b e d s o r c o n c e n t r a t e d a l o n g t h e b e d d i n gp l a n e s . C o p p e r, t h o u g h n o t a b u n d a n t , r e p l a c e dp a r t of t h e s e p l a n t r e m a i n s . At t h e C a l i f o r n i amine ore occur red i n t h in -be d d ed a l t e r n a t i n g l a v e nd e r and w h i t e , f i n e - g r a i n e d s a n d s t o n e s , somewhats h e a r e d and s t r o n g l y f l e x e d . Nor th a t t h e MaggieMine th e bed g r a d e d i n t o an a l t e r n a t i n g s e r i e s ofw h i t e , f i n e - g r a i n e d s a n d s t o n e s and r e d d i s h browns h a l e s 1 -2 i n c h e s or more t h i c k . An e x c e p t i o n t oth e g e n e r a l ore occur rence i s n o t a b l e a few hundred

- 151 -



~ :i!

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EXPLANATION

0 Surface s tope

=® Underground workings

ELEVATION390(

0

IZI

•0

200

Shaf t

Raise

Winze

Scale

'po 89 0

F i g u r e 1 3 . Known u n d e rg r o u n d workingsi n t h e Tecumseh mine a r e a .

1200 F e e tI



f e e t s o u t h e a s t o f t h e Savage S h a f t y h e r e s i l v e rm i n e r a l s y e r e a p p a r e n t l y d e p o s i t e d a c r o s s t h e . b e dding i n a s h e a r zone i n b r o y n i s h t o l a v e n d e r s a n ds t o n e s . M i n e r a l i z e d rock ya s s t o p e d f o r some 220

f e e t a long t h e s t r i k e of t h e s h e a r and t o 40 f e e ti n Yi d t h .

Tecumseh H i l l Group. - The o r i g i n a l d i s c o v e r yof ore i n p l a c e yas made on t h e S i l v e r F l a t c la imon th e e a s t s i d e of Tecumseh H i l l . I n many p l a c e son th e h i l l s u r f a c e s t r a t a were l i t e r a l l y s t r i p p e df rom t h e a r e a t o r e c o v e r t h e s i l v e r . L a t e r ,Tecumseh H i l l i t s e l f was honeycombed by undergroundwork ings . Most of t hese a re now only p a r t l y a c c e ss i b l e and many of th e a c c e s s i b l e workings a re p a r tl y b a c k f i l l e d w i t h w a s t e r o c k . Known w o r k i n g sshown i n f i g u r e 13 i nc lude not more t han 50 p e r c e n tof t h e t o t a l of t h e Tecumseh H i l l a r e a . Miningwas conf ined t o th e Tecumseh sands tone beds on th en o r t h nose of t h e h i l l , b u t n e a r t h e c e n t e r orewas mined f rom t h e c o n t a c t of t h e Tecumseh andLeeds s a n d s t o n e . Accord ing t o o ld r e c o r d s (Macf a r l a n e , p . 7 6 , 1 8 7 7 ) t h e o re b e d s y e r e t h i n ,a v e r a g i n g only 1 0 - 1 8 i n c h e s i n t h i c k n e s s . Someof t h e s e , h o w e v e r, were e x c e p t i o n a l l y r i c h andhad t h i n p l a t e s of c e r a r g y r i t e a l o n g t h e b e d d i n gp l a n e s . B a r b e e ' s o r i g i n a l sh ipment from t h i s a r e ara n $502 t o th e t o n .

The ore o c c u r r e d i n a t l e a s t t h r e e h o r i z o n sas s i l v e r was mined from t h e Tecumseh-Leeds s a n ds t o n e c o n t a c t and two o t h e r h o r i z o n s 7-10 f e e t and20 f e e t r e s p e c t i v e l y above th e Tecumseh b a s a l c o nt a c t . Some of th e e x t e n s i v e Manhat tan mine s t o p e soccur approx imate ly 30 f e e t above the Tecumseh b a s a lc o n t a c t . The main a re h o r i z o n was a f i n e l y l a m in a t e d , f i n e - g r a i n e d , l a v e n d e r sands tone which c o nt a i n e d numerous impress ions of s m a l l f o s s i l p l a n t sa long t h e b e d d i n g . In some p l a c e s t h e s e f o s s i l swere r e p l a c e d by s i l v e r c h l o r i d e . Near th e middleof Tecumseh H i l l a whi te t o b u ff f i n e - g r a i n e d s a n ds t o n e c o n t a i n i n g p l a n t f o s s i l s p a r t l y r e p l a c e d bym a l a c h i t e and a l s o some c l a y g a l l s was mined f o ri t s s i l v e r c o n t e n t .

- 153 -



I- '\J"I.t--

II

BARBEE AND WALKERCOMPANY

YEAR Mines Contro l led:Barbee & Walker

1877

1878 Barbee & Walker 5-Stamp mil l c om-

ple ted March, 18781879 June 23 , 1879 f i r e

des t royed BarbeeMil l .

880 Barbee & WalkerS11 ver Mining Co.incorpora ted June1, 1880. Feb. 27 ,1880 m i l l r e b u i l t .Product ion $211,58l .

~ 8 8 l Product ion $205,524, Lab or s t r i k e3-15-81 to 7-17-81

1882 Pr oduc ti on(100,000+ ozs. of

s i l v e r . Company inf i n a n c i a l embarrasa-ment.

-- - -

STORMONT MINING & LEEDS COMPANYMILLING COMPANY

Mines Contro l led:Mines Contro l led: Leeds

St orm ont , Buckeye, Leeds #2Thompson, McNally,Last Chance

Feb. , l877-Leeds5 Stamp Mil l . Aut-umn, l877-c ompanyorganized.

Ju ly 4 , 1878, Sto r-mont Mil l completed.

Stormont Mining & Product ion $114,436Milling Co. inc or- Mil l from custompora ted Ju ly 19 , ores and others1879. yie lded $768,321.58

to 6-1-80 .

Pr oducti on Product ion$484,110. $29,255.

Product ion Product ion $11,300$265,658 10-10-81 to 12-31-

Opera t ions suspen- 81 . Leeds Mil l downde d 2-1-81 t o 7-1- fo r almost 2 years8 l . t o October 10, 1881

Pr oduction Company i n t o hands239,975 ozs. of s i l - of c r e d i t o r s .ver.

- - - - - - - - - - - - - - - - - - - - _ . -- - - - - - - - - - - - - --

-CHRISTY MINING &

MILLING COMPANY OFCALIFORNIA

Mines Contro l led:Tecumseh, Si lve r Fla t ,Si lve r Crown, S i l v e r REFERENCES

Point ,Chloride C h i e f , M a g g i ~

Cal i f ornia ,Manhatton,Stormy KingChris ty Company i n - Engineer ing an dcorpora ted f a l l of Mining Jou rna l s -1877. A.I.M.E.

J a n . , 1878, 5-Stampmil l completed.Product ion $ 3 0 2 , ~ 3 7 .

Product ion Mi ning Rec or d of$245,466 New York; Tenth

Annual Census, Veil

13, p. l 3 r "Pre -c i ou s Met als" , p •482.

Product ion Tenth Annual Cen-$272,084. s u s , vo l . 13 , p.

13; "Prec i ousMeta ls" , p. 482,Direc to r of th em i n t ; a l s o a quotefrom "Mining Re -cord" .

Pr oduct i on Report of th e Dir-$316,040 e c t or of Mint,

"Prec ious Metals"f o r 1881, p. 23 9(H.C. Burchard)

Pr oduct i on Repor t of th e u i r -$372,426. e c t o r of Mint,

"Prec ious Meta ls"f o r 1882, p. 25 4(H. C. Burchard)



.....

V l

V l

1883

1884

1885

1886

88 7

)1888

Product ion-no r e - P r o d u c t i o n P r o d u c t i o n R e p o r t of t h e D i r -c o r d . Worked by (182 ,000 ozs . ) $262 ,310 . e c t o r o f M i n t ,G i l l e s p i e - L u n d & Co. (5 0 men employed) " P r e c i ous Met a l s n

16 men employed. f o r 1883 , p . 6 ~ ? ,H. C. B u r c h a r d

Pr oduc ti on n ot P r o d u c t i o n - n o r e - P r o d u c t i o n R e p o r t of t h e D i r -known. Company i n t 0 c o r d . 90 men em - 234 ,217 ozs . e c t or of M i n t ,l i q u i d a t i o n . p l o y e d . Company c a l l e d " P r e c i o u s M e t a l s "

C h r i s t y Mining Co . f o r 1 8 8 4 , p . 403,( R e o r ~ _ a n iz e d ? J . (H . C. B u r c h a r d ) .

P r o d u c t i o n - n o r e -5

s tamps o p e r a t i n g . R e p o r t of t h e D i r -c o r d . 10 s t amps No r e c o r d of p r o - e c t o r of M i n t .o p e r a t i n g . d u c t i o n . " P r e c i o u s M e t a l s "

f o r 1 8 8 5 , p . 1 8 1 ,( J . P. K i m b a l l ) .

P r o d u c t i o n Leeds M i l l purchased P r o d u c t i on R e p o r t o f t h e D i r -$167 ,000 . by H a r d i n g , B a i l e y $232 ,000 . e c t or of M i n t ,

& N e s b i t t an d c on - " P r e c i o u s M e t a l s "v e r t e d t o l e a c h i n g f o r 1886 , p . 225,p l a n t . F a i l u r e b e - ( J . P. K i m b a l l ) .c a u s e of c o p p e r c on -t e n t .

I d l e d u r i n g g r e a t - Fo r 1887-88 l i s t e d R e p o r t of t h e D i r -e s t p a r t of y e a r . as main ly p r o d u c t - e c t o r of M i n t ,Company end? io n from C h r i s t y " P r e c i o u s M e t a l s "

an d La Vi rg i n . f o r 1887 , p. 24 3Doubt fu l i f old c om- ( J . P. K i m b a l l ) .pany s t i l l e x i s t e n t .No p r o d u c t i o n r e -c o r d .

P r o d u c t i o n $263 ,466La Virg in M i l l .

- - ~ - - - - - - ~ - - - - - - - . - - - -.------------

Table 8 . Av a i l a b l e h i s t o r y an d p r o d u c t i o n of major companies an d mines a tS i l v e r R e e f , U t a h , 1877-1888 . P r o d u c t i o n l i s t e d probably i n c l u d e s cus tomore s e n t t h r o u g h th e r e s p e c t i v e m i l l s from d i f f e r e n t mines i n th e d i s t r i c t .



E a s t R e e f G r o u p , Va n d e r b i l t Mine . - A fews m a l l m i n e s and many p r o s p e c t p i t s and i n c l i n e sp e n e t r a t e t h e E a s t Reef f rom t h e Va n d e r b i l t minesou th t o th e a d i t on th e Maud c la im. The Va n d e r b i l ti s r e a c h e d by a 120 f o o t i n c l i n e and a few s m a l ld r i f t s mos t of which a r e a c c e s s i b l e . B u t l e r (p .586 , 1920) r e c o r d s a $ 2 4 , 0 0 0 p r o d u c t i o n f rom th emine f rom 240 t o n s of o r e . The s i l v e r o c c u r r e di n a whi t e , f i n e - g r a i n e d sands tone wi th in th e Leedssands tone 2-3 f e e t below th e Tecumseh b a s a l c o n t a c t .Smal l f a u l t s t r e n d i n g n o r t h 20 w e s t d r o p th e bedsa few f e e t t o t h e e a s t .

To q u e r v i l l e Mine. - The To q u e r v i l l e mine i s1400 f e e t sou th of t h e Va n d e r b i l t and i s a c c e s s i b l eby a main i n c l i n e and two s m a l l open ings a long th ef ace of th e r e e f . Approx ima te ly 800 f e e t of worki ngs a re a c c e s s i b l e along th e f ace of th e E a s t Reef .The s topes a re smal l , t he l a r g e s t be ing approx ima tel y 25 f e e t wide and 35 f e e t l o n g , and n o t exceedingf i v e f e e t i n h e i g h t . Lagg ing a l o n g t h e i n c l i n ew a l l s may c o v e r o t h e r s m a l l s t o p e s . Other s m a l l ,

p a r t l y c a v e d s t o p e s o c c u r a l o n g t h e f a c e of t h er e e f j u s t s o u t h of t h e main i n c l i n e , b u t as f a ras c o u l d be d e t e r m i n e d t h e s e do n o t c o n n e c t w i t ht h e main w o r k i n g s .

Mining was compl i ca t ed by s e v e r a l f a u l t s t r e n din g no r th 20 w e s t , 70-75 degrees e a s t , with a downdrop t o th e e a s t . The main i n c l i n e ends a g a i n s t a

f a u l t which s t r i k e s N. 11 W. and d i p s 74 E. The ore

h o r i z o n s o c c u r as s m a l l 2 -4 f o o t t h i c k l e n s e s ofw h i t e , f i n e - g r a i n e d s a n d s t o n e which t h i c k e n andt h i n down t h e d i p . The l e n s e s l i e 2 -6 f e e t undert h e Tecumseh sands tone b a s a l c o n t a c t . Minor amountsof copper ca rbona t e s a re a s s o c i a t e d wi th p l a n t r emains i n t h e ore bed. According t o B u t l e r (p . 586,1920) s e v e r a l hundred t ons of ore averaged $50.00p e r t o n i n s i l v e r . S m a l l s h o w i n g s of c a r n o t i t ed i s s e m i n a t e d i n l a v e n d e r s ands tone occur 200 f e e tn o r t h e a s t of t h e main i n c l i n e .

Duff in Mine. - The Duff in Mine l i e s i n a s m a l lv a l l e y s o u t h of th e prominen t v o l c a n i c cone on th eE a s t Reef . Seve ra l i n c l i n e s open i n t o s m a l l s t o p e sand 900 f e e t of p a r t l y a c c e s s i b l e workings . A caved

- 156 -



s h a f t on t h e e a s t s i d e of t h e r e e f was o r i g i n a l l yused t o w i t h d r a w t h e o re f rom t h e m i n e . The o reoccur red i n a l e n s of l a v e n d e r t o gray f i n e - g r a i n e ds a n d s t o n e 20 f e e t above th e c o n t a c t of th e Tecumseh-Leeds s a n d s t o n e s . C a r n o t i t e , m a l a c h i t e , m i n o r

a z u r i t e , and s m a l l s p e c k s of s i l v e r c h l o r i d e a rev i s i b l e i n some of t h e dump s p e c i m e n s .

Maud, Utah , and Rough Rider c l a i m s . - C o n s i d e r-a b l e deve lopmen t work was done a long t h e wes t f a c eo f t h e E a s t R e e f s o u t h of t h e D u f f i n m i n e . Twos h o r t a d i t s c u t th e r e e f f rom a v a l l e y on t h e backs l o p e on t h e U t a h c l a i m . S e v e r a l i n c l i n e s ands h a f t s a r e on t h e d i p s l o p e o f t h e r e e f w e s ~of

t h e a d i t p o r t a l s . M i n i n g a p p e a r s t o h a v e b e e nr e s t r i c t e d t o s h i p m e n t s o f s o r t e d o r e f rom t h es o u t h a d i t and Maud i n c l i n e s . The sh ipment s p r o b a -b l y do n o t exceed a t h o u s a n d t o n s . The b e d s c o n -s i s t of f i n e - g r a i n e d , b u f f t o whi te s a n d s t o n e whichc o n t a i n a b u n d a n t m a l a c h i t e r e p l a c i n g and s t a i n i n gp l a n t r e m a i n s . On t h e Maud c l a im a bed w i t h prom-i n e n t amoun t s of m a l a c h i t e 300 f e e t l o n g and t os i x f e e t t h i c k c r o p s o u t a l o n g t h e w e s t f a c e o f

t h e r e e f . A ll of th e ore h o r i zons a r e i n t h e Leedss a n d s t o n e i n t h i s a r e a and l i e a few f e e t below th eTecumseh c o n t a c t .

- 157 -



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p . 204, 1904.

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H u n t l e y, D. B . , The mining i n d u s t r y o f Utah , p r e -c i o u s m e t a l s , t e n t h c e n s u s , U. S . , v o l . 13,pp . 477-82, 1885.

I r w i n , J . S . , F a u l t i n g i n t h e Rocky Mtn. r e g i o n ,B u l l . A. A. P. G ., v o l . 10, pp . 105-129, 1926.

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of t h e Laramie B a s i n , A s t u d y 2ll g e n e s i s ofs e d i m e n t s , Univ. of Wyo. P u b l . i n S c i . , Geol .v o l . 1 , # 1 , pp . 1 -82 , 1929 .

K o e b e r l i n , F. R . , D is cu s s ion of s e d i m e n t a r y c o p p e r,v a n a d i u m - u r a n i u m and s i l v e r i n s o u t h w e s t e r nUni t ed S t a t e s ( b y ~P. F i s c h e r ) , Ec. G e o l .v o l . 3 3 , N o . 4 , 458 - 461 , 1 9 3 8 .

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Lawson, A. C . , The go ld of t h e Shinarump ~ P a r i a :Econ. Geol . , v o l . 8, pp. 434-448, 1913.

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McKee, E. D ., O r i g i n a l s t r u c t u r e s i n Colorado Rive rf l o o d d e p o s i t s of Grand Canyon, J o u r n . Sed .P e t r o l o g y , v o l . 8 , p p . 7 8 - 8 3 , 1 9 3 8 .

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162





A b s t r a c t , 1

A c k n o w l e d g m e n t s , 6Adams, 68A g a t e b e d , 20A l l u v i u m

Q u a t e r n a r y , 39B o u l d e r , 3 9 - 4 1R e c e n t , 41

INDEX

A m e r i c a n C y a n i m i d , 109112

A n d e r s o n , 3 2 , 134A n d r e , 32A n t i c l i n e

V i r g i n , 44-45L e e d s , 45

A p a t i t e , 120A m e r i c a n S m e l t i n g &

R e f i n i n g Company, 6S h a f t , 8 , 2 8 , 74

A r g e n t i t e , 1 0 7 - 8A s s a y s , 21A u t u n i t e , 113A z u r i t e , 8 4 , 1 0 9 , 132

B a k e r , 1 4 , 29B a l l , 5 , 1 6 , 25 , 62, 80,

9 7 , 1 0 1 , 1 0 9 , 123B a r b e e , W. T . , 69B a s a l t , 4 2 - 4 3

Basin & Range Prov ince , 44Bas t i n , 133, 135B a s s l e r , 1 2 , 1 5 , 23 , 38B e a t h , 140Bedding, Cross , 26-7, 33-5Benton i t e , 21, 138Born i t e , 112

S o l u t i on o f , 130B o u l d e r a l l u v i u m , 39-40B r a n s on, 29Buckeye Mine , 88Buckeye R e e f , 19

S i l v e r , 85-89C o p p e r, 89-94

U r a n i u m - v a n a d i u m , 95

B u r c h a r d , 68B u r w e l l , 125B u t l e r , 5 , 1 2 , 1 6 , 2 5 ,

6 2 , 74 , 9 7 , 107 , 123 ,1 3 5 , 156

B u t t e R e e f , 33S a n d s t o n e , 19C o p p e r , 95U r a n i u m - v a n a d i u m , 95

C a l c i t e , 11 7 , 119C a l l a g h a n , 6 , 44C a n n o n , 1 3 8 , 140C a r n o t i t e , 11 0 , 113C e d a r C i t y , 7

C e r a r g y r i t e , 1 0 5 , I I I

C h a l c o c i t e , 84, 109 , 114S o l u t i o n o f , 130

C h a l c o p y r i t e , 112S o l u t i o n o f , 130

Channe l sS t r eam, 1 5 , 2 5, 3 2 , 3 5

Chinle formation, 12, 16-37Lower, 18-22M e a s u r e d s e c t i o n , 17U p p e r , 3 7 - 3 8

ChI o r i t e , 117Chr i s ty Mil l i ng and Mining

Canpany, 71Clay

B a l l s , 28, 31-32Gal l s , 28, 31-32Gumbo, 24

C l i f f s , 8Claims

Mining, 145-146Colbath, 6, 52, 74, 81Col l e r, 107C 0 1 orad 0 P l a t e a u , 9Canpanies

Mining , h i s t o r y , 154-155



C o n c r e t i o n s , 20A s s a y r e p o r t o n , 20

C o n g l o m e r a t e , 15Cone

Vo l c a n i c , 42C o p p e r , 21

B u c k e y e R e e f , 8 9 , 92B u t t e R e e f , 95E a s t R e e f , 96R e l a t i o n t o ca rbon ized

s u b s t a n c e s , 10R e l a t i o n t o s i l v e r

c o n t e n t , 1 0 2Rela t ion t o r a d i o a c t i v e

mine ra l s , 103White Reef , 84

Crane, 5, 16 , 25 , 6 2 , 124Crawford, x , 6

Cross-bedding , 15 , 25-27 ,33

Local d e l t a , 26 , 33-34Channe l , 2 6 , 2 7 , 3 3 - 3 4Flow, 2 7 , 3 3 - 3 5

C r o s s - l a m i n a t i o n , 33C u p r i t e , 109

De i s s , 6

Diamond d r i l l c o r e , 6

D i c k e r t , 70D o b b i n , 5 , 4 4 , 6 2 , 66Drag f o l d s , 59Dr ough t , 8

D u f f i n m i n e , 1 9 , 44Duffin sandstone, 30 , 36-37

M e a s u r e d s e c t i o n , 37

E a s t R e e f , 5 , 19C o p p e r, 96M i n e s , 1 5 6 - 1 5 7S i l v e r , 95

Uranium-vanadium, 95-96Economic geo logy, 68-104

H i s t ory, 68-75E l g i n , 5

E l e v a t i o n s , 8

Emb o l i t e , 106Emmons, 1 2 9 , 132E h r h o r n , 6

F a u l t s , 50 -6 7Age, 65 -67Buckeye R e e f , 52Ea s t R e e f , 5 5

Normal , 51-55T h r u s t , 56 , 59-65T r a i l H i l l , 52

Virgin a n t i c l i n e , 54-55White Reef , 51

F a y, 33F i e l d w o r k , 5

F i s c h e r , 1 2 4 - 1 2 5 , 139F i r e C l a y H i l l

Benton i t e s h a l e s , 19 ,21Copper, 89

FlowsVolcan ic , 1. 2

Fo lds , 44Vi r g i n a n t i c l i n e , 44Leeds a n t i c l i n e , 45-46

L e e d s s y n c l i n e , 4 7F o s s i l s , 12, 15 , 24, 28-29

Gangue m i n e r a l s , 116-120Gardner, 5 , 12 , 3 9 , 44,65Garre l and S t i n e s , 132Garne t , 118Genesis of depos i t s , 12 l - l 42G e o d e s , 20Geo log i c s e t t i n g , 1 2 - 6 7G i l l u l y , 29Gold , 2 1 , 81G o l d t h w a i t , 12G r a b a u , 32Gr ego ry, 1 2 , 1 4 , 29Gwynn, 6

Gypsum, 1 3 , 120

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H a r r i s b u r g d i s t r i c t , 7

Harr i sburg dome, 12 , 44H a r t l ~ ,6, 73, 81, 83, 112Hartley shales and sandst 0 ne

19H a l i t e , 120Heath , 6

Heavy m i n e r a l s , 117 , 118Hewet t , 14H i n t z e , 134Hunt ing ton , 12Hunt l ey, 89

Hurr icane c l i f f ,9

Hurr icane f a u l t , 9Hyper s thene , 118

I g n e ous r o c k , 4 2 - 4 3I n d i a n a U n i v e r s i t y , 6

I n t r o d u c t i o n , 4

I r w i n , 5 5 , 66I r o n o x i d e , 1 1 1 , . 1 1 7

J a s p e r , 2 3 , 120J e n n e y , 1 0 6 , 112J o h n s , 6

J o i n t s , 4 7 , 49B u c k e y e R e e f , 4 8 - 4 9B u t t e R e e f , 49E a s t R e e f , 49O r i g i n , 4 9 - 5 0W h i t e R e e f , 48

K a o l i n i t e , 1 19K e m p l e , 68K o e b e r l i n , 1 3 9 - 1 4 0

L a h e e , 3 2L a m i n a t i o n

C r o s s , 33L a t i t e

B o u l d e r s , 39L a u s e n , 139Lawson , 138L e e d s , 7 -9

A n t i c l i n e , 45

Company, 70Mil l , 71Sands tone , 25-28, 29,30

S y n c l i n e , 47L e i n i n g e r, 115Limest one

S i l i c e ous , 22L i g h t m i n e r a l s , 116 , 118L i n d g r e n , 1 2 3 , 1 2 6 , 136L oc a t i on o f , Ar e a , 7

Longwe l l , 14L o v e r i n g , 135

M a c F a r l a n e , 155M a l a c h i t e , 84

M i n e r a l , 108 , 110P r e c i p i t a t i o n o f , 132

Mason, 134McCleave , 69McKee, 34McMul l in , 6 , 69 , 106

Means, 62Member, 13Mica , 28M i c r o c l i n e , 118M i l l s

Barbee and Walke r, 71C h r i s t y , 71Flow s h e e t , 72Leeds , 71

Magnet , 71S t orm o n t , 71

M i l l i n gC o s t s , 71L o s s e s , 71 , 73

M i n e r a l monument , 8 , 70M i n e r a l d e p o s i t s , 78

C h a r a c t e r , 78-82Grade , 80Shape , 79

M i n e r a l o g y, 80 , 105-121Mines , 8 , 143-157

B a r b e e & Wa l k e r , 298 2 , 8 4 , 1 4 7 - 1 4 8

B u c k e y e , 8 7 - 8 8

166





S a n dWind b l o w n , 41

S a n d s t o n eA r k o s i c , 1 6L e e d s , 2 5 - 2 8 , 2 9 - 3 0N a v a j o , 3 8

P i t t e d w e a t h e r i n g , 31S i l v e r Reef , 16 , 23-25Tecumseh, 28-30T r a i l H i l l , 22

Sc o t t , 32Schne ide r, 112

S e a r s , 14S e c t i o n , 13Sedimenta ry r o c k s , 12-41Se len ide

S i l v e r , 107Selen ium, 107 , 140

R e l a t i o n t o c o p p e r,uranium-vanadium, 103

S h a l e s , 13

B e n t o n i t i c , 16Green , 22S h e l l O i l Company, 6

Shinarump c o n g l o m e r a t e ,1 2 , 1 4 - 1 6

Measured s e c t i o n , 15Shnabka ib member, 12-13S i l v e r , 106

Buckeye R e e f , 85-89

B u t t e R e e f , 9 4E a s t R e e f , 9 5 - 9 6N a t i v e , 106Rela t ion t o carbon , 101Relat ion to ca rbana te , lO lR e l a t i on t o coppe r, 102Rela t ion t o r a d i o a c t i v e

m i n e r a l s , 102-103Se1enide , 107S o l u t i o n o f , 131-132P r e c i p i t a t i o n o f , 132

S m i t h ' s Mesa, 23S p r i n g s , 8

S t o k e s , 14

S t ormontM i l l , 8

Mine, 148St reams

T r i a s s i c , 128Direct ion of f low, 35-36

S t . George Basin , 9

S t r u c t u r a l c o n t r o l ofo r e , 9 6 - 1 0 0

S t r u c t u r a l s e t t i n g o fd i s t r i c t , 44

S t r u c t u r e s

C h a n n e l , 9 6 - 9 7F a u l t s , ~ 0 - 6 7 ,99F o l d s , 4 4 - 4 7 , 9 7J o i n t s , 4 7 - 4 9 , 98S h e a r s , 99

S t u g a r d , 5 , 9 2 - 9 3 , 9 5 ,1 0 3 , 115

S u l f a t e r e d u c e r s , 136S u r f a c e f e a t u r e s , 8 -9

TecumsehH i l l , 1 9 , 2 8 , 29M i n e , 1 5 3 , 154S a n d s t o n e , 2 8 - 3 0

T e n o r i t e , 109Thermal a n a l y s e s , 22-23T h r u s t f a u l t s , 56

D i s p l a c e m e n t , 64-65

E v i d e n c e , 56 , 60-64Timber, 8

To q u e r v i l l e mine , 45To u r m a l i n e , 120T ou w a id e , 139T r a i l H i l l s a n d s t o n e , 22Trees

S i l i c i f i e d , 19Twenh of e l , 131

U n c o n f o r m i t i e s , 15U n d e rg r o u n d map, 5 , 8U. S. S o i l C o n s e r v a t i o nUtah Depar tmen t of Pub-

l i c i t y , 6

168



Uranium-vanadium, 85Buckeye Reef , 92-94But te Reef , 95Eas t Reef , 95-96Rela t ion t o carbonized

subs tance , 101Relat ion t o s i l v e r cont e n t , 102

Relation to copper, vanadium, selenium, 103

Va n d e r b i l t mine, 41, 45Virg in C i t y, 15 , 23 , 24Virg in R i v e r, 8

Virg inA n t i c l i n e , 44-45Limes tone , 12

Vi t a l i a n d , 22Vanadium

Relat ion to uranium

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