Libby Montana Vermiculite Mine

Libby Montana Vermiculite Mine
W.R. Grace
Maps and geologic information from: Boettcher, A.L., 1966,
The Rainy Creek alkaline-ultramafic igneous complex near
Libby Montana
Libby,
Montana, JJ. Geology
Geology, vv. 75
75, p
p. 526-553
526 553.
Location of
Facilities
Libby Vermiculite Mine
Rainy Creek
Pluton
Rainy Creek Pluton
Definitions – rock names
• Fenite – narrow hydrothermally altered zone
off Na-metasomatism,
N
t
ti
hydrolysis,
h d l i and
d
oxidation, with increased sodium, hydrous
silicates
ili t and
dh
hematite
tit
• Biotitite – rock composed
almost entirely of biotite
• Syenite
y
–p
plutonic rock w/
low Quartz, 10<P/A+P<35
Minerals
• Biotite – K(Mg,Fe2+)3(AlSi3O10)(OH)2
• Hydrobiotite – formula about halfway in between Bt
and Vermiculite, considered to be a high T alteration
product of Biotite ((Boettcher,, 1966))
p
• Vermiculite –
3+
(Mg,Ca)0.3
0 3(Mg,Fe ,Al)3(Al,Si)4O10(OH)4 - 8H2O
originated by leaching of biotite by ground waters
((removal of alkalis and oxidation of Fe2+ to Fe3+
Boettcher, 1966)
y
(from
(
hydrothermal
y
• Amphiboles – useless byproduct
alteration of pyroxene), more later
W R Grace wanted the vermiculite
W.R.
• Mostly in Biotitite
• Amphibole asbestos is intimately
associated with vermiculite
vermiculite, but is useless
Rainy Creek
Pluton
Sheet silicate structures
Vermiculite Structure
Expansion Process
- vermiculite
i lit was shipped
hi
d allll over th
the
US for processing
• Vermiculite is heated for a few seconds to
1100oC
• Water present in vermiculite structure
vaporizes to steam and forces layers of
sheet silicate apart
• This creates the usable product
Unexpanded
p
and Expanded
p
Vermiculite
Location of
Facilities
Uses of Expanded Vermiculite
•
•
•
•
•
•
•
Insulation
Fireproofing
B lki agents
Bulking
t
Absorbents
Soil amendments
Industrial fillers
Packing material
Libby
A hib l
Amphibole
analyses –
note
t Fe
F 3+
and Fe2+
From Gunter, et al., 2003,
Composition … of amphiboles
from Libby,
y, MT,, American
Mineralogist, v. 88, p. 19701978.
Naming Amphiboles
• Why should we care?
• Only reibeckite, grunerite, anthophyllite,
actinolite and tremolite amphiboles are
regulated as asbestos by the US EPA
• Non
Non-mineralogists
mineralogists call Libby amphiboles
tremolite; are they, really?
• No, they are other amphiboles called
winchite or richterite
• Other amphibole asbestos minerals are
just as bad, but are not regulated!
Naming Amphiboles
• How is it done?
• Follow specific rules for assigning
elements in chemical analysis of an
amphibole to different sites in the formula
• Leake,
L k ett al.,
l 1997
1997, N
Nomenclature
l t
off
amphiboles…, American Mineralogist, 82,
1019 1037
1019-1037.
Amphibole Formula
AB2C5T8O22(OH)2
(Na,K)
(Na
K)0-1(Ca,Na,Fe,Mg)
(Ca Na Fe Mg)2(Mg,Fe,Al)
(Mg Fe Al)5(Si,Al)
(Si Al)8O22(OH,F)
(OH F)2
large
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)
Naming sodicsodic
calcic amphiboles
per Leake,
L k ett al.,
l
1997
Mineralogist’s Names for Libby
A hib l
Amphiboles
• They are sodic-calcic amphiboles
• Some 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
video
id
• Big Sky Pictures
• Produced,
Produced directed and edited by Drury
Gunn Carr & Doug Hawes-Davis
Libby, Montana Asbestos Cleanup Reaches
Major Milestone With Mountaintop Park
In this April 28, 2011 photo, D.C. Orr, a city councilman in Libby, Mont., stands in
th middle
the
iddl off a storage
t
area, where
h
b
bark
k and
d wood
d chips
hi contaminated
t i t d with
ith
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
p g show they
y contain minimal levels of asbestos,, according
g to a report
p
Friday Jan. 13, 2012.The findings appear to offer a rare bit of relief for this town of
Libby, where wide