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Libby Montana Vermiculite MineLibby Montana Vermiculite Mine
W.R. GraceW.R. Grace
Maps and geologic information from: Boettcher, A.L., 1966, The Rainy Creek alkaline-ultramafic igneous complex near Libby Montana J Geology v 75 p 526-553Libby, Montana, J. Geology, v. 75, p. 526 553.
Definitions – rock names
• Fenite – narrow hydrothermally altered zone f N t ti h d l i dof Na-metasomatism, hydrolysis, and
oxidation, with increased sodium, hydrous ili t d h titsilicates and hematite
• Biotitite – rock composed almost entirely of biotite
• Syenite – plutonic rock w/y plow Quartz, 10<P/A+P<35
Minerals• Biotite – K(Mg,Fe2+)3(AlSi3O10)(OH)2
• Hydrobiotite – formula about halfway in between Bt• Hydrobiotite – formula about halfway in between Bt and Vermiculite, considered to be a high T alteration product of Biotite (Boettcher, 1966)p ( , )
• Vermiculite –(Mg,Ca)0 3(Mg,Fe3+,Al)3(Al,Si)4O10(OH)4 - 8H2O(Mg,Ca)0.3(Mg,Fe ,Al)3(Al,Si)4O10(OH)4 8H2Ooriginated by leaching of biotite by ground waters (removal of alkalis and oxidation of Fe2+ to Fe3+(Boettcher, 1966)
• Amphiboles – useless byproduct (from hydrothermal y ( yalteration of pyroxene), more later
W R Grace wanted the vermiculiteW.R. Grace wanted the vermiculite
• Mostly in BiotititeMostly in Biotitite• Amphibole asbestos is intimately
associated with vermiculite but is uselessassociated with vermiculite, but is useless
Expansion Processi lit hi d ll th- vermiculite was shipped all over the
US for processing
• Vermiculite is heated for a few seconds to 1100oC
• Water present in vermiculite structureWater present in vermiculite structure vaporizes to steam and forces layers of sheet silicate apartsheet silicate apart
• This creates the usable product
Uses of Expanded VermiculiteUses of Expanded Vermiculite
• InsulationInsulation• Fireproofing
B lki t• Bulking agents• Absorbents• Soil amendments• Industrial fillersIndustrial fillers• Packing material
Libby A hib lAmphibole analyses –
t F 3+note Fe3+
and Fe2+
From Gunter, et al., 2003, Composition … of amphiboles from Libby, MT, American y, ,Mineralogist, v. 88, p. 1970-1978.
Naming AmphibolesNaming Amphiboles
• Why should we care?Why should we care?• Only reibeckite, grunerite, anthophyllite,
actinolite and tremolite amphiboles areactinolite and tremolite amphiboles are regulated as asbestos by the US EPA
• Non-mineralogists call Libby amphibolesNon mineralogists call Libby amphiboles tremolite; are they, really?
• No, they are other amphiboles calledNo, they are other amphiboles called winchite or richterite
• Other amphibole asbestos minerals areOther amphibole asbestos minerals are just as bad, but are not regulated!
Naming AmphibolesNaming Amphiboles
• How is it done?How is it done?• Follow specific rules for assigning
elements in chemical analysis of anelements in chemical analysis of an amphibole to different sites in the formulaL k t l 1997 N l t f• Leake, et al., 1997, Nomenclature of amphiboles…, American Mineralogist, 82, 1019 10371019-1037.
Amphibole FormulaAmphibole FormulaAB2C5T8O22(OH)2
(Na K) (Ca Na Fe Mg) (Mg Fe Al) (Si Al) O (OH F)(Na,K)0-1(Ca,Na,Fe,Mg)2(Mg,Fe,Al)5(Si,Al)8O22(OH,F)2large medium small tetrahedral
Libby Amphiboles
• (Na.14K.13) (Ca1.25Na.73) (Mg4.24Fe3+.41Fe2+
.30)Si8.0O22(OH,F)
• (Na.32K.19) (Ca1.12Na.85) (Mg4.43Fe3+.34Fe2+
.18)Si8.0O22(OH1.63F.37)
Mineralogist’s Names for Libby A hib lAmphiboles
• They are sodic-calcic amphiboles• Some classify as richteriteSome classify as richterite• Some classify as winchite
• They are not even in the same group as tremolite (a calcic amphibole), which is the name used in the media
Selections from Libby, Montana idvideo
• Big Sky Pictures• Produced directed and edited by DruryProduced, directed and edited by Drury
Gunn Carr & Doug Hawes-Davis
Libby, Montana Asbestos Cleanup Reaches Major Milestone With Mountaintop ParkMajor Milestone With Mountaintop Park
In this April 28, 2011 photo, D.C. Orr, a city councilman in Libby, Mont., stands in th iddl f t h b k d d hi t i t d iththe middle of a storage area, where bark and wood chips contaminated with undetermined levels of lethal asbestos were stored. Test results from huge piles of woodchips that were being sold from a Montana Superfund site for use in landscaping show they contain minimal levels of asbestos, according to a report p g y , g pFriday Jan. 13, 2012.The findings appear to offer a rare bit of relief for this town of Libby, where wide