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Title The system NaFe^<3+>Si_2O_6-CaFe^<2+>Si_2O_6 at low oxygene fugacity
Author(s) Ohta, Kohei; Onuma, Kosuke; Yagi, Kenzo
Citation Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy, 17(3), 487-504
Issue Date 1977-02
Doc URL http://hdl.handle.net/2115/36070
Type bulletin (article)
File Information 17(3)_487-504.pdf
Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP
Jour. Fac. ScL, Hokkaido Univ., Ser. IV,
vol. 17, no. 3, Feb., 1977, pp. 487-504.
487
THE SYSTEM NaFe3'Si2 06 -CaFe2'Si2 06
AT LOW OXYGEN FUGACITY
by
Kohei Ohta*, Kosuke Onuma aRd Kenzo Yagi
(with i table and 8 text-figures)
(Contribution from the Depaitment of Geology and Mineralogy,
Facuity of Science, Hokkaido University, No. 1482)
Abstract
,,,,T,h.e,gF.F,e.e",S;'g.O,z-/j,Ck?8r,`.8f,Sh,e,2Y,Ste.i",lll,a.F.e;ES,k2P.z:,C,?.,F,g,2'.S,ikO,-%,w,as.glgleg.'i,'ile61,a,t
atm. It was found that a high temperature foTm of hedenbergite has not 6-wollastonitestructure, but bustamite structure in the temperature range of iiOOOC-11750C. Three
Fe2'-bearing silicate phases were also confirmed by X-ray diffraction patterns and optical
properties: Fe-bustamitess, 6-Fe-wollastonitess, and or-Fe-wollastonitess (ss: solid solution).
These t}iree phases are solid solutions between CaSi03 and FeSi03 at low oxygen fugacity;
NaFe3'Si206 enters into the liquid when the crystalline phases coexist with liquid. The
following phase assemblages were encountered with increasing temperature: Fe-bustamitess
+ iron oxide + liquid, B-Fe-woliastonitess + Fe-bustamitess + iron oxide ÷ liquid,6-Fe-wollastonitess + iron oxide + liquid, 6-Fe-wollastonitess + a-Fe-wollastonitess + iron
oxide + liquid, and or-Fe-wollastonitess + iron oxide + liquid. The assembfages are essentially
the same throughout the range of oxygen fugacity investigated, except that magnetiteconverts to wthstite at low oxygen fugacity. Application of the system to the natural
pyroxene is also given.
Introduction
From experimental study of the system acmite-diopside and the natural
pyroxene from alkalic rocks, Yagi (1966) suggested that there are continuous
solid solutions in the system acmite-diopside-hedenbergite. Later Ohashi (1967)
confirrned the presence of a ccomplete seriesof solid solutions in the system
acmite-hedeRbergite at subsolidus teinperature, and Nolan (i969) showed that
continuous solid solutions exist in the subsolidus region of the system
diopside-hedenbergite-acmite. However, investigatioRs of the high temperature
region in the system acmite-hedenbergite has not yet been accomplished.
Bowen et al. (1933), investigating the system CaO-FeO-Si02 , demonstrated
that 6-wollastonite forms a solid solutioR with ferrosilite, which enters into
6-wollastonite up to 70 mole percent at high temperature with the substitution
* Present Address: Nippon Cement Co., Tokyo
488 K. Ohta, K. Onuma and K. Yagi
of Fe2' for Ca. Recently, many studies on the system CaO-FeO-Si02 were
carried out and the problems related to the structure of high temperature forms
of hedenbergite are presented (Peacor and Prewitt, 1963; Prewitt and Peacor,
1964; Rutstein, 197l ; Rutstein and White, l971 ; Matsueda, 1973).
From his experimental study Rutstein (l971) claimed that Fe2' cannot
substitute for Ca more than about 10 atomic percent in the 6-wollastonite
structure, and that specimens containing more than IO percent Fe2' have
bustamite structtire. Matsueda (1973), from his study of natural specimens as
well as experimental work on the system 6-wollastonite-ferrosilite, concluded
that the structure of iron wollastonite is different from that of6-wollastonite.
In the present study the phase diagram of the system acmite-hedenbergite is
determiAed at the teinperattire i'ange of lIOOOC - 12500C and at the oxygen
fugacity (fo, ) of 1O-9 - IC}-i i atm and the structural problem of CaFe2'Si2 06
is also discussed.
Experimental Methods
The ordinary quenching method was employed for the iiivestigation of the
phase diagram.
Homogeneous glasses were prepared by melting pure chemicals in aPtg o Rhi o crucible previously saturated with iron. Pure quartz, Fe2 03 , CaC03
and pure Na2 Si2 Os were used as sources. These homogeneous glasses were used
as starting materials for quenching experiments. Starting materials were held in
Pt6oRh4o envelopes in order to minimize the loss of iroii and suspended in a
vertical quenching furnace. A Pt-Pts 7 Rlii 3 thermocouple used to measure the
temperature was calibrated at the standard melting points of Au (I062.60C)
and diopside (1391.SOC).
The atmosphere in the furnace was controlled by running mjxtures of C02
and H2 gas at definite ratios. Calibration fof oxygen fugacity was made by
examining the stability field of hematite, magnetite, and wUstite.
X-ray diffraction pattems of the crystalline phases were obtained with
Ct}Ka radiation at 35 KV and 20 mA at room temperature. Reflections of
(210) and (I02) of 6-wollastonite, and (204) and (204) of bustamite were
obtained at a scaiming speed of 114 degree per minute, with silicon as an
external standard.
Experimental Results and DiscussioRs
e-ystalline phases
In the present experiment three different silicate phases were recognized.
THE SYSTEM NaFe3"Si2 06 -CaFe2'Si2 06 489
e A3.1OO
3.050
3.000
Lo
tog Po2=-11
Jp
ee
d2o4
CaFeSi206tj
FeBusss.WUs.L
I
fl1-i-l
/1-i---・
llll,fi-FeWos6d
i,EeHusssi'' WUs.L i I
fi-FeWOss.WUs.L
1100
l
1150 o1200 C
o A3.300
3.250
3.200
LogPo2=-11
li
dio4
Ca Fe S i206
ee
-d
FeBvsss.WUs.L
'
1!1t-I"
1-l.-../
lbln-FeWessli.FeBusss"
Hl1.WUs.L ,
ltpln-FeWoss.WOs.L
llOO 1150Teraperature
ol200 C
Fig. 1 Changes of d-spacings of B-Fe-wollastonitess and Fe-bustamitess crystailized fromthe composition of CaFe2"Si2 06 at 1OMi i atm fo2 . The open circles represent d2 i o
and dio2 of B-woilastonite and the soiid circles d2o4 and dio4 of bustamite. The
following abbrevations wil1 be used throughout all figures and tables. Fe-Bus =
Fe-bustamite, B-Fe-Wo = 6-Fe-wollastonite, or-Fe-Wo = or-Fe-wollastonite, WUs =
wUstite, Mt = magnetite.
From the X-ray dif{lraction patterns and optical data, it is suggested that these
three crystalline phases correspond to bustaminess, 6-woliastoRitess, and
a-wollastonitess. As all of these phases incorporate Fe2', henceforth these
phases will be described as Fe-bustamitess, 6-Fe-wollastonitess, and or--Fe-
wollastonitess, respectively. The 6-wollastonitess and the or-wollastonitess
represent wollastoRitess and pseudowollastonitess, respectively, as defined by
Bowen et aL (1933).
X-ray 'diffraction patterns of bustamite and 6-wollastonite are similar, but
490
o A3,1OO
3.050
3000
to
K. Ohta, K. Onuma and K. Yagi
Log Po2= --1 O
d 2o4
l-t----l-
"caFesi2o6" Irl---p /ee
i/ FeBusss.Fe-oxide .L l?FJe[Beuljssi .C}IF. se) LOss
"Wus.L l ll
11 00 11 50 e1200 C
t
e A3,300
3.250
3.200
Log Po2=-1 O
d io4
"CaFeSi206" l/ / l/l
FeSusss.Fe・・oxTtie.L
l t/----ldi
Trl---
ttil.,'eFi,Wu/tsil.:;-.F:Tl,oss
i/I1100 1150
Tery}perature
o1200 C
Fig. 2 Change of d-spacings of 6-Fe-wollastonitess and Fe-bustamitess crystallized fromthe composition of CaFe2"Si2 06 at 1OMi O atm fo2 . The open circles represent d2 i o
and die2 of 6-wollastonite and the solid circles d2o4 and d7o4 of bustamite.
Abbrevations are same as in Fig. 1.
the peaks of bustamite are located at 1-1.50 higher angle side in 2e compared
to 5-wollastonite. The diffi'action peaks, liowever, shift to the bustamite side
due to Fe2' substitution for Ca in the B-wollastonite structure and it may
become difficult to determine whether the structure of・the phases present
belongs to 6-woilastonite or to bustamite when 6-wollastonitess contains
considerable amounts of Fe2'.
The crystalline material of composition CaFe2"Si2 06 was prepared at fo,
of lcrii and IOmiO atm to examine whether these two phases are mutually
distinguishable or not. Figs. I and 2 show the changes of d-spacings of(204) as
a function of temperature. Only one peak corresponding to that of bustamite
THE SYSTEM NaFe3'Si2 06 -CaFe2'Si2 06 49l
Log Po2=-11 "CaFeSi2o6"
t7oo fXIxxllx
,,,,
el-XS-S-iXXGs'h`l"xx:l)iitti,,
1.600 FeBuigs-Was+L
b・Fel.vo,g
: Fe B.u S
l wws,Ll
l!
I-I-nvslxl-I-I
.nQF.e,w.e,ss i
l
Ixl-a-FeVtoss.n-FeWoss,WUs.L
;1 OO 11 50 1200 o1250 C
1.700
1.650
1.600
I Log Po2=-11 "Acio-Hdgolllllllllllllll'lllllXlvV-l
:
tt
IIxl
FeBusss.W"s+L
k・fewo,S
aFeelssst
lWU'5,Ll
ll
I I-xl?.":",W.2ss
I a-FeWessI :B.L,f,eW.,Oss
::
Fig. 3
o 1100 1150 1200 1250C Temperature
Change of refractive indices of 6-Fe-wollastonitess and Fe-bustamitess crystallized
from the compositions of CaFe2'Si206 and AcioHdge at IOMii atm fo2.Abbrevations are same as in Fig. 1.
was observed and the d-spacing increases with increasing temperature between
1lOOOC and 1l750C. The peak of (2e4) splits at 1i80 and l1850C, giving two
different d-spacings. One is similar to the d-spacing of 6-wollastonite and the
other to that of bustamite. However, at higher temperatures again only one
peak was observed, which gave a d-spacing similar to that of 6-wollastonite
(Figs. I and 2).
Optical methods are also useful to identify the si}icate phases encountered.
Two silicate phases A and B were observed in the ruR charges of the
492 I<. Ohta, K. Onuma and K. Yagi
I Log po2=-io . .i-7 00 1/ -ixi , Ca Fe Si2o6
t650
1.600
iXxx
FeBusss.Fe-ox[de.L
1100
×KI'xlvl-- a IXIvi-- ---l-HKI XI- ---I-I-I----Ns--Ih--Ns-I-
.?.'Fae.:"//s:ln-Fewassl .::FF.""bUe;.s
`WUs.L .yv"s-L i d r ,Wss.L LIl cli Ld1 ,・・L11 50 1200 nso a c
i7oo I
1,650
L600
Log Po2=-ulO
lXiIxlxXXxXII
FeBusss.Fe-oxide.L
"Acio-Hdgo"
r×}-I--
×-I-. al-I l-Ixl II I-Ixl i.fiEeFSV:s5sSi n-Fewoss l .:JFFeewWeess:
.W"s.t d.WUs.L, i ,WUs.L tl/ di/ didFig. 4
e llOO 1150 1200 1250C Ternperature
Change of refractive indices of 6-Fe-wollastonitess and Fe-bustamitess crystaliized
from the compositions of CaFe2'Si206 and AcioHdgo at' iO-iO atm fo2.Abbrevations are same as in Fig. 1.
composition of CaFe2'Si206 at ll800C and 11850C and also that ofAcioHdgo at 1l7SOC. These two phases sliow different refractive indices as
follows: A-phase or = 1.628 ± O.O03, 7= 1.642 ± O.O03; B-phase a = 1.647 ±
O.O03, 7 = 1.662 ± O.O03. The A-phase was not encountered below theseteinperatures and the B-phase disappears above these temperatures. Coinparing
with the X-ray data it is evident that the A-phase corresponds to the6-wollastonite structure and the B-phase to the bustamite structure.The changes
of refractive indices as a function of temperature are given in ITigs. 3, 4, and S.
If the 6-wollastonitess changes in cornpositioA while maintaing its structure, the
d-spacing and the refractive indices should change continuously. However, as
seen in Figs. I, 2, 3, 4, and 5, the changes of these values are discontinuous,
indicating that there should be some change in the structural state. The
obseivations mentioned above lead to the following conclusion: the phase with
THE SYSTEM NaFe3'Si2 06 -CaFe2'Si2 06 493
l
1.7oo e
1.650
1.600
Log Po2=-9
"CaFeSi206" INXI r IXIXXL-m ------ a I---- mm""I IXIx -'T-I I-NIx Add 4 n-FeWess , d fi-FeWoss i a-FeLYess FeBusss.Mt.L +Feeusss , i +Fe-oxide i +n-FeWoss .Mt+L , i ,L i .W"sd 4il bbi il tL.
1100 11 50 1200'-""rmt'-""'-
o 1250 C
i7oo I
1.650
1600
LogPo2=--9
lilllll5
a
d-
Acio " Ncigo
IL}}
i-
FeBtisss+Ml.L
{XI・------INIi? gBW2gt:sl B-Fewo,s
.Ut+LUMt.L l
IIII
I a-FeWess::"F.Jg-e.W,,O-ds.s
:,Ll
Fig. 5
o llOO 1150 1200 1250C Tefnperature
Change of refractive indlces of a-Fe-wollastonitess and Fe-bustamitess crystallized
from the compositions of CaFe2'Si206 and AcioHdgo at 10-9 atm fo2.Abbrevations are same as in Fig. 1.
low refractive indices and larger d-spacing has 6-wollastonite structure, whereas
the phase with high refractive indices and smaller d-spacing is presumed to have
bustamite structure.
Rutstein (1971) fotmd that bustamite with composition between(Cao.gFeo.i)Si03 and (Cao.sFeo.2)Si03 shows a split in the peaks of X-ray
diffraction patterns, indicating the presence of two phases. He also distingushed
these two phases by infrared spectral analyses and concluded that these two
phases correspond to the structures of 6-wollastonite and bustamite, althougli
their optical properties were not giveR. Matsueda (1973) found the natural
mineral to have different structure from 6-wollastonite and called the structure
of this mineral "iron wollastonite structure" which corresponds to the
bustamite investigated by Rutstein. Since in the present study the presence of
494 K. ohta, K. onuma and K. Yagi
B-wollastonite structure including Fe2' is recognized in addition to or-
wollastonite and bustamite structures, it is not proper to use the term "iroR
wollastonite" for the mineral which has a bustamite structure.
IR the present investigation, therefore, the three phases mentioned above
are called a-Fe-wollastonitess, 6-Fe-wollastonitess and Fe-bustamitess, because
X-ray diffraction patterns are shifted from the pure compounds, indicating that
Fe2" is incorporated iR the structures. Since there is some confusion concerning
the structural states of these phases according to different workers, the
Aomenclature is compared in Table l.
TabEel The structural states of or-Fe-wollastonite, B-Fe-wollastonite, and
Fe-bustamite by different workers.
Phasepresentinthisstudy Structuralstates
Rutstein(1971) Matsueda(1973)
cr-Fe-wollastonite - -B-Fe-wollastonite B-woNastonite 6-wollastonite
Fe-bustarnite bustamite ironwollastonite
Under the microscope the Fe-bustamitess forms nearly equant plates at
lower temperatures and slender plates or prisms at higher temperatures, both
being about O.04 - O.Ol mm in length. The 6-Fe-wollastonitess forms slender
piates or prisms, about O.04 - O.Ol mm in length. Both of them are pale green
and non-pleochroic. The or-Fe-wollastonitess forms equant plates or squares,
about O.02 - O.04 mm in size. Pleochorism is distiiict as follows: X' = colorless,
Z' =: pale green. The or-wollastonitess is distinguished from the other phases by
its high birefringence. In addition to the silicate phases very small amounts of
oxide minerals, magnetite and wUstite, are preseAt throughout all runs.
Phase diagrams
Results of quenching experiments for the oxygen fugacities IO-i i, IO-'O
10-9 atm are listed iR appendices 1, 2, and 3 with refractive indices of the
silicate minerals, and the phase diagrams for each of the isobaiic sections are
shown in Figs. 6, 7, and 8. The transition boundary of wUstite and magRetite is
calculated from the data of Darken and Gurry (1945) to locate # at 11430C at
10-'O atm and l2700C at 10-9 atm.
At 10-' ' atm fo, , the following assemblages were encountered with falling
temperature: or-Fe-wollastonitess + w"stite + Iiquid, or-Fe-wollastonitess +
6-Fe-wollastonitess + wUstite -t- liquid, B-I?e-wollastonite + wUstite + liquid,
6-Fe-wollastonitess + Fe-bustamitess + wUstite + liquid, and Fe-bustamitess +
THE SYSTEM NaFe3'Si2 06 -CaFe2"Si2 06 495
x
Log Po2= --11
x
o
L
x
o
o
xe
xe
xao
a-FeWess.WUs.L
s
o
a-f"Wess-fi-feVtoss.W"s,L
e
oo
oo on-FtWoss.W"s.t
o o
o"o
eae o
g
o
e
o
o
o
e
o
a
o
F"Eusss.W"s.L
v
n-kWess.FeBusss.W"s.L
n o
'ce 1250
e
? 1200
o
e :t:・ N x E fl
n t150
o
o llO・:i
NaFeSi206 30 40 so
Fig.6 Phase diagram of the system Abbrevations are given in Fig. 1.
6o 7o 80 90 CaFeSi206 mot el.
NaFe3'Si206-CaFe2'Si206 at 10-ii atm fo2.
wtlstite + liquid. In the sections with fo, of 10m'O and 10-9, the same
assemblages were confirmed, except that wthstite converts to magnetite at lower
temperatures.
In each section it is observed that the upper stability of each phase
assernblage increases with increasing CaFe2'Si2 06 and also that the stability
field of each assemblage increases with decreasing fo, . On the other hand, the
liquid field extends towards CaFe2'Si2 06 with increasing fo, ・
Since the present system is a join of a five-component system, Na2 O-CaO-
Fe-O-Si02 , the iso-fugacity T-X section is not binary, but pseudo-binaiTy. When
the composition is projected from the oxygen apex onto the Fe-Si02 line,
magnetite and wUstite are compositionally coincident, so that the system is
treated as a four-component system in the analysis of phase assemblages (see
Lindsley et al., 1968). Therefore, a five-phase assemblage is univariant and a
four-phase assemblage is divariant. In the 10mi' atm section two divariant
assemblages are present, B-Fe-wollastonitess + Fe-bustamitess + wtlstite + liquid
aiid or-Fe-wollastonitess + 6-Fe-wollastonitess + wUstite + liquid. In the 10miO
atm and IO-9 atm sections, the magnetite-wUstite inversion curve appears and
496 K. Ohta, K. Onuma and K. Yagi
Log Po2=-1O
L
x
xoo
x
xOoo
oo a-FeWOssWUs.L
G e
a-FeWoss.n-FeWess.Wdis,L
o
fi-FeWess.FeBusss.Wes.L
o
n-FeWoss.WUs.L
o
o
a
o
]
a
FeBusss.WUs,L
n
e co 1.250
e
o 1200
An.
a 1150
2aatLgEs
x
FeSusss.Mt.L
di eR el e s:t FiWeSS /B Fewoss FeBvsssMt L
e fi " m e za
M
e 1100
Fig. 7
NaFeSi206 40 50
Phase diagram of the systemAbbrevations are given in Fig. 1.
6o 7o 80 90 CaFeSi206 mo l elo
NaFe3'Si206-CaFe2'Si206 at IOrmiO atm fo2.
crosses the divariant assemblage fields mentioned above, resulting in the
presence of univariant assemblages: 6-Fe--wollastonitess + Fe-bustamitess +
wUstite + magnetite + liquid (10MiO) and or-Fe-wollastonitess + 6-Fe-
wollastonitess + wC}stite + magnetite + liquid. Therefore, the univariant curve
indicating these two assemblages lias a pesitive slope in the T-fo, prQjection
aiid must lie on the magnetite-wUstite inversion plaiie which is independent of
the composition in the T-X-fo, space. These two univariant curves meet
together at an invariant point where or-Fe-wollastonitess, 6-Fe-wollastonitess,
Fe-bustamitess magnetite, and wt'istite coexist with liquid.
When Fe3' is not present at low fo2 , say 10" i, sodium can not enter iiito
the crystalline phases in the form of NaFe3'Si2 e6 , but all of this molecule is
contained in the liquid. However, when magnetite is present, indicating the
existence of Fe3', it is possible that sorne of the Fe3', in the form of
NaFe3'Si2 06 , can be incorporated in the silicate phases and the remainder is
contained in the liquid. The amount of Fe3' in the silicate phases may increase
THE SYSTEM NaFe3'Si2 06-CaFe2'Si2 06 497
Log Po2=-9 x
x
・w:I.reLW
o a-feWess.n-FeWoss.W"s+L
I"c
l250
e
L
x
xe
x di m
XM ts N
e e el200a-FeYVoss.B-FeWoss.Mt.L
/Te
fi-FeWoss.Mt.L
e
m
m
as
FeBusss.Mt,L
m
S-FeWess.FeBusss.Mt.L
e ee
e
za 1150
ee
m "od
o..iEI
NxgN
NaFeSi206 40 50 6o
Fig.8 Phase diagram of the system Abbrevations are given in fig. 1.
7o so 90 CaFeSi206 mo l Olo
NaFe3'Si206-CaFe2'Si206 at IO-9 atm fo2.
with decreasing amount of liquid and finally a complete series of solid solutions
between NaFe3'Si2 06 and CaFe2'Si2 06 is formed at subsolidus ternperatures
as demonstrated by Ohashi (i976).
Application to natural pyroxene
The present experimental evidence supports the former conclusion ofYagi
(1966) that at low fo, the pyroxene trend proceeds from diopsidic towards
hedenbergitic and at high fo, from diopsidic through soda augite to aegirtne.
Recently Ewart et al. (1976) called attention to the fact that acmite-enrich-
ment occurs oRly after extreme Fe-enrichment and not only fo, but activity of
alumina in liquid plays an important role in detennining the courses mentioned
above. The presence of the acmite molecule in pyroxene also depends upon the
concentration of calcium in the liquid. From their experimental studies Onuma
and Yagi (1975) and Yoshikawa and Onuma (197S) suggested that at high fo,
498 K. Ohta K. Onuma and K Yagi
when enough calcium and aluminum are present Fe3" enters into pyroxene in
the form of CaFe3'AISi06 and sodium forms nepheline, also that pyroxene
proceeds towards acmite only when Na > Fe3' + Al, as pointed out by
Huckenholz (1973) in his study of natural pyroxene.
The above statement leads to the following conclusion: When fo2 is higher
than the magnetite-wtstite transition curve, pyroxene becomes acmitic in the
case of Na > Fe3' + Al, or fassaitic in the case of Na < Fe3' + Al; when fo, is
lower than the magnetite-wUstite curve, it becomes hedenbergitic in either case.
Acknowleclgements The authors' thanks are due to Mr. Haruo Ohashi ofthe National Institute
for Research in IRorganic Materials for his help in the experimental technique,
aRd Dr. N.C. Stevens of University of Queensland for his cr#ical reading of the
paper in manuscript. Part of the cost for the present study was defrayed by
Grant for Scientific Research from the Ministry of Education of Japan, and a
grant from the Mitsubishi Foundation.
References
Bowen, N.L., J.F. Schairer, and E. Posnj.ak, l933. The system CaO-FeO-SiO?. Am. J, Sei.,
26: l93-284.Darken, L.S. and R.W. Gurry, l945. The system iron-oxygen. I. The whstite field and related
equibria. J. Am. Chem. Soc., 67: l398-l412.Ewart, A., A. Mateen and J.A. Ross, l976. Review of mineralogy and chemistry of Tertiary
central volcanic complexes in southeast Queensland and northeast New South Wales.
Vblcanism in Australasia, Ed. by R.W. Johnson, 21-39.Huckenholz,1 .G. I973. The origin of fassaitic augite in the alkali basalt in suite of the
Hocheifel area, Western Germany. Contr. Min. Pet., 40: 3l5-326.
Lindsley, D.H., D.H. Speidel and R.H. Nafziger, 1968. P-T-fo relation for the system
Fe-O-Si02.Am. L Sci., 266: 342-360.Matsueda, H.,i973. Iron-wollastonite from the Sampo mine showing properties distinct from
those of wollastonite. Mineral. J., 7: l80-201.
Nolan, J., 1969. Physical properties of synthetic and natural pyroxenes in the system
diopside-hedenbergite-acmite. Mineral. Mag., 37: 2l6r229.
Ohashi, H., 1967. The systern acmite-hedenbergite. M. Sc. Thesis Hokkaido Univ. (in
Japanese).Onuma, K. and K. Yagi, 1975. Thejoin CaMgSi2 06-CaAl2 Si06-CaFe3"AISi06 in air and its
bearing on fassaitic pyroxene. J, Eac. Sci., HOkkaido Uhiv., Ser. 4, l6: 343-356.
Peacor, D.R. and C.T. Prewitt, 1963. Comparison of the crystal structures of bustamite and
wollastonite. Am. Mineral., 48: 588-596.Prewitt, C.T. and D.R. Peacor, 1964. Crystal chernistry of the pyroxenes and pyroxenoids.
Am. Mineral,, 49: 1527-1542.Rutstein, M.S., 1971. Re-examination of the wollastonite-hedenbergite (CaSi03-CaFeSi2 06)
499 THE SYSTEM NaFe3'Si2 06 -CaFe2'Si206
equilibira. Am. Mineral., 56: 204e-2052.Rustein, M.S. and W.B. White, l971. Vibrational spectra of high-calcium pyroxenes and
pyroxenoids. Am. Mineral. 56: 877-887.Yagi, K., l966. The system acmite-diopside and its bearing on the stability relations of
natural pyroxenes of the acmite-hedenbergite-diepside series Am. Mineral., 51:'
976-IOeO.Yoshikawa, K. and K. Onuma, 1975. The join NaFeSi206-CaAl2Si06 at 1 atmospheric and high pressure: Part I. Phase relations at 1 atm pressure in air. J. lapan. Assoc. Min.
Pet, Econ. Geol., 70: 335-346.
(Received on Oct. 21, 1976)
soe
Appendix 1
K. Ohta, K. Onuma and K. Yagi
Results of quenching experiments for the system
CaFel2Si206 at 10-'i atm fb, and refractivepyroxenoids.
NaFof3Si206 -indices of the
Compositioll (mol %)
Ac HdTemp. (oC) Phases
Reftractive indices
(±O.O03)
or7o
le
20
100
90
se
1100
1125
1150
1175
1180
1185
1195
l2eo
1225
1250
1100
1125
ll50
1165
1175
1185
ll95
12oe
1225
125e
lleo
1125
1150
1165
ll75
1195
noe
1225
1250
Fe-bus÷wtis+gl
Fe-bus+wtis+gl
Fe-bus+wifs+gl
Fe-bus+wtis+gl
6-Fe-wo+Fe-bus+wiis+gl
6-Fe-we+Fe-bus+wifs+gl
6-Fe-wo+whs÷gl
6-Fe-wo+wiis+gl
a-Fe-wo+B-Fe-wo+wUs+gl
a-Fe-wo+B-Fe-wo+wUs+gl
Fe-bus+wiis+gl
Fe-bus+whs+gl
Fe-bus+w"s+gl
Fe-bus+wtis+gl
B-Fe-wo+Fe-bus+wUs+gl
6-Fe-wo+wiis+gl
B-Fe-wo+wifs+gl
6-Fe-wo+wiis+gl
or-Fe-wo+B-Fe-wo+wUs+gl
a-Fe-wo+wiis+gl
Fe-bus+wtis+gl
Fe-bus+wtis+gl
Fe-bus+wtis+gl
6-Fe-wo+Fe-bus+wUs+gl
6-Fe-wo+wtis+gl
B-Fe-wo+wus+gl
or -Fe-wo+fi -Fe-wo+wtis+gl
a-Fe-wo+B-Fe-wo+wUs+gl
or-Fe-wo+wiis+gl
1.685
1.680
l.673
1.654
L6511.628
1.650
l.628
1.626
1.627
l.625
l.609
1.624
1.609
1.675
1.666
1.655
1.650
1.649
1.628
1.626
1.626
1.626
1.624
1.609
1.609
1.658
1.655
1.649
1.647
1.628
1.626
1.625
1.622
1.610
l.623
1.609
1.609
1.705
1.700
l.688
1.669
1.664
1.642
1.663
1.641
l.640
l.641
1.638
L6521.638
L653
1.691
1.683
1.669
1.664
1,662
1.642
1.640
1.64e
1.640
1.638
1.653
1.654
1.674
1.669
1.663
L6621.642
1.640
1.639
1.636
1.653
1.636
1.653
1.653
Fe-bus
Fe-bus
Fe-bus
Fe-bus
Fe-bus
6-Fe-wo
Fe-bus
6-Fe-wo
B-Fe-wo
6-Fe-wo
6-Fe-wo
or-Fe-wo
6-Fe-wo
or -Fe-wo
Fe-bus
Fe-bus
Fe-bus
Fe-bus
Fe-bus
B -Fe-wo
6-Fe-wo
6 -Fe-wo
6 -Fe-wo
B-Fe-wo
cr -Fe-wo
or-Fe-wo
Fe-bus
Fe-bus
Fe-bus
Fe-bus
6-Fe-wo
6-Fe-wo
5-Fe-wo
B-Fe-wo
a-Fe-wo
6 -Fe-wo
or-Fe-wo
cr -Fe-wo
T正{ESYST君M NaFe3+Si206・CaFe2+Si206
Appe薮db【1(continued)
Colnpbsitioll
(mol%)
Ac Hd
Temp.(OC)
PhasesRe負ractive indices (±0.003)
α 7
30
35
40
45
50
60
70
70
65
60
55
50
40
30
1100
1125
1150
1175
U95
1225
1250
1125
1185
1200
1225
1250
1100
1125
1150
1175
1185
1200
1225
1100
1175
1200
1100
1125
1150
1175
1100
1125
1100
Fe-bus+wOs+gl
Fe-bus+w丘s+gl
β一Fe-wo+w昼s+gl
β一Fe-wo+wUs+9董
α一Fe-wo+β一Fe-wo+w麺s+gl
α一Fe-wo÷wUs+gl
α一Fe-WO+wUS+gl
β一Fe-wo+Fe-bus+wUs+gl
β一Fe-wo+wUs+gl
α一Fe-wo+β・Fe-wo+w酋s+gl
α一Fe-WO+W麺S+gl
91
Fe-bus÷輔s÷gl
β+Fe-wo+w鷲s+91
β一Fe-wo+wUs+gi
β一Fe-WO+W昼S+gl
β一Fe-wo+wUs+9韮
α一Fe-wo÷β一Fe-wo+wOs+9蓋
gi
β一Fe-wo+Fe-bus+w通s+9董
β一Fe-wo+w種s+9正
gl
β一Fe-WO+W已S+gl
β一Fe-wo+w態s+gi
β一Fe-WO+W睦S+gl
9隻
β一Fe-wo+w礒s+gl
9藍
麟
互.655
1.652
1.626
1.622
1.622
1.609
1.609
1.609
L648
1.628
1.625
L623
1.609
L610
L652
1.626
L624
1.624
1.624
1.621
1.610
1.649
1.627
1。624
1.627
1.625
1.623
1.623
正.668
1.665
1.639
L634
互.636
1.654
L653
互.652
正.662
1.642
1.639
1.636
1.653
1.653
1.666
1.640
L638
1.637
1.638
1.635
1.653
1.663
1.641
1.636
1.640
1.638
1.634
1.636
Fe-bus
Fe-bus
β一Fe-w・
β一Fe-wo
β一Fe-wo
α一Fe-wo
α一Fe-WO
α一Fe-wo
Fe-bUS
β一Fe-WO
β一Fe-wo
β一Fe-wo
α一Fe-WO
α一Fe-wo
Fe-bus
β一Fe-wo
β一Fe-w・
β一Fe-wo
β一Fe-wo
β一Fe-WO
α一Fe-wo
Fe-bus
β一Fe-wo
β一Fe-w・
β一Fe-w・
β一Fe-WO
β一Fe-wo
β一Fe-wo
Abbrevations ale g{ven in Fig。1.
501
502
Appendix 2
K. Ohta, K. Onuma and K. Yagi
Results of quenching experiments for the system
CaFof2Si206 at 10-iO atm fo, and refhractiye
pyroxenoids.
NaFe'3Si206 -indices of the
Composition (mol %)
Ac HdTemp. (oC) Phases
Refhractive indices
(±o.eo3)
or7o
IO
20
30
100
90
80
70
1100
1125
1150
l165
1175
1185
1190
1200
1225
l250
1100
1l25
115e
1165
1175
l185
1200
1225
l250
neo1l25
1150
noe
1225
125e
11eo
l125
l150
1190
Fe-bus+mt+gl
Fe-bus+mt+gl
Fe-bus+w"s+gl
Fe-bus+wUs+gl
Fe-bus-w"s+gi
B-Fe-wo+Fe-bus+w"s+gl
B-Fe-wo+wus+gl
B-Fe-wo+wus+gl
or-Fe-wo+B-Fe-wo+wUs+gl
a-Fe-wo+B-Fe-wo÷wiis+gl
Fe-bus+mt+gl
Fe-bus+mt+gl
Fe-bus+wUs+gl
6-Fe-wo+Fe-bus+wiis+gl
5-Fe-wo+Fe-bus+wUs+gl
6-Fe-wo+wus+gl
6-Fe-wo+wiis+gl
or-Fe-wo-+z(3-Fe-wo+wiis+gl
or-Fe-wo+wtis+gl
Fe-bus+mt+gl
Fe-bus+mt+gl
6-Fe-wo+Fe-bus+wiis+gl
or-Fe-wo+B
-Fe-wo+wifs+gi
or-Fe-wo+B-Fe-wo+wlis+gl
or-Fe-wo+wiis+gl
Fe-bus+mt+gl
Fe-bus+mt+gl
6-Fe-wo÷wus+gl
P-Fe-wo+wUs+gi
1.683
1.674
1.667
1.653
1.650
1.648
l.629
1.628
1.628
l.627
1.6e9
1.623
1.609
1.670
l.663
L6551.649
1.628
1.649
1.628
1.626
1.626
1.625
1.609
l.609
1.655
1.651
1.648
1.629
1.621
1.609
1.623
L6091.609
1.654
1.650
1.626
l.622
1.7eo
1.691
L681
1.667
1.664
1.663
1,642
1.641
l.641
1.640
1.653
L636
1.652
L6831.678
1.669
l.663
1.641
1.662
l.641
l.640
1.639
L6381.653
1.652
1.669
l.665
1.662
1.642
l.638
1.654
1.636
1.653
1.653
1.658
l.664
1.640
1.636
Fe-bus
Fe-bus
Fe-bus
Fe-bus
Fe-bus
Fe-bus
B-Fe-wo
B-Fe-wo
6 -Fe-wo
B-Fe-wo
a-Fe-wo
6-Fe-wo
cr -Fe-wo
Fe-bus
Fe-bus
Fe-bus
Fe-bus
B-Fe-wo
Fe-bus
6-Fe-wo
6-Fe-wo
6-Fe-wo
6-Fe-wo
or -Fe-wo
a-Fe-wo
Fe-bus
Fe-bus
Fe-bus
6-Fe-wo
6-Fe-wo
a-Fe-wo
B-Fe-wo
or -Fe-wo
a-Fe-wo
Fe-bus
Fe-bus
6-Fe-wo
6-Fe-wo
THE SYSTEM NaFe3"Si2 06 -CaFe2"Si2 06
Appendix 2 (continued)
S03
Composition (mol %)
Ac HdTemp. (oC) Phases
Refractive indices
(±e,oo3)
a7
35
40
45
50
6e
65
60
55
50
40
1200
1225
1125
1175
119e
1200
1100
i125
1150
1175
11eo
1150
1100
1125
1150
1100
or-Fe-wo+6-Fe-wo+wiis+gl egl
gi
6-Fe-wo+Fe-bus+mt+gl
6-Fe-wo+wUs+gi
6-Fe-wo+wiis+gl
gi
Fe-bus+mt+gl
6-Fe-wo+mt+gl
6-Fe-wo÷wus+gl
gl
B-Fe-wo+Fe-bus+mt+gl
6-Fe-wo+wgs+gl
B-Fe-wo+mt+gl
5-Fe-wo+mt+gl
gl
gl
1.620
1.609
1.648
1.628
1.624
1.622
1.650
1.626
-1.623
1.648
1,627
1.622
1.623
1.622
1.634
1.653
1.662
1.642
1.637
1.636
1,664
L6401.636
1.662
1.642
1.635
1.635
1.635
6-Fe-wo
a-Fe-wo
Fe-bus
6-Fe-wo
6 -Fe-wo
B-Fe-wo
Fe-bus
6-Fe-wo
6-Fe-wo
Fe-bus
B-Fe-wo
6-Fe-wo
B -Fe-wo
6-Fe-we
Abbrevations afe given in Fig. 1.
504
Appendix 3
K. Ohta, K. Onuma and K. Yagi
Results of quenchlng experiments for the system
CaFe'2Si206 at 10r9 atm fo, and refra¢tivepyroxenoids.
NaFe'3Si206 -indices of tlie
Composition (mol %)
Ac HdTemp. (oC) Phases
Refractive indices
(±o.eo3)
a7o
10
20
3e
35
40
45
100
90
80
70
65
60
55
1100
l125
1150
1175
l185
1200
1225
ilOO
1125
1150
ll75
1200
1225
1250
llOO
1125
l150
1175
l200
l225
1100
1125
i150
1175
1100
1l25
l150
1100
1l25
1100
Fe-bus+mt+gl
Fe-bus+mt-gl
Fe-bus+mt-gl
Fe-bus+mt-gl
6-Fe-wo+mt+gl
6-Fe-wo+mt+gl
or-Fe-wo+6-Fe-wo+wUs+gl
Fe-bus+mt+gl
Fe-bus+mt+gl
Fe+bus+mit+gl
6-Fe-wo+Fe-bus+mt+gl
6-Fe-wo+mt+gl
a-Fe-wo+wtis+gl
gl
Fe-bus+mt+gl
Fe-bus+mt+gl
6-Fe-wo+Fe-bus+mt+gl
6-Fe-wo+mt÷gl
a-Fe-wo+6-Fe-wo+mt+gl
gl
Fe-bus+mt+gl
6-Fe-wo+Fe-bus+mt+gl
B-Fe-wo+mt+gl
gl
B-Fe-wo+Fe-bus+mt+gl
B-Fe-wo+mt+gl
gl
6-Fe-wo+mt+gl
gl
gl
1.671
1.666
l.650
l.626
1.624
1.623
1.608
1.666
1.659
1.651
1.647
1.627
1.625
1.609
l.655
1.653
1.647
1.627
l.627
1.625
1.6e9
l.650
1.648
1.627
`1.628
1.647
l.628
l.625
1.623
1.687
1.680
L6651.640
L6381.636
1.653
1.680
1.672
1.666
1.662
1.641
1.638
1.653
l.668
1.666
l.661
1.640
1.640
l.638
1.651
1.664
1.662
1.641
1.641
1.664
1.642
1.638
1.636
Fe-bus
Fe-bus
Fe-bus
B-Fe-wo
B -Fe-wo
B-Fe-wo
or-Fe-wo
Fe-bus
Fe-bus
Fe-bus
Fe-bus
6-Fe-wo
6-Fe-wo
or-Fe-wo
Fe-bus
Fe-bus
Fe-bus
B-Fe-wo
B-Fe-wo
B -Fe-wo
or -Fe-wo
Fe-bus
Fe-bus
B -Fe-wo
B-Fe-wo
Fe-bus
B-Fe-wo
B -Fe-wo
6-Fe-wo
Abbrevations are given in Fig. 1.