Preview
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
EXHIBIT 81
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
: i
I{
THE GEOLOGY OF MONTANA TALC DEPOSITS
~~
I!·'
by Richard H. Olson
1;:
ABSTRACT
\r ..r,
J! ;
Talc deposits in the Precambrian of southwestern Montana ;i..
(Beaverhead and Madison Counties) are unique within the U.S. A. in that
p:·
; IC
large bodies of tremolite-free talc can be open-pit mined. All known
/, :;
I>
deposits are in pre- Beltian dolomite units. The origin is suspected to be : ~~
metasomatic, with the siliceous component having been contributed by an
intrusive Precambrian granite gneiss. Precambrian deformation was
,,
•• ' t.
it..
; {
il.: t
extreme and is characterized by multiple periods of tight isoclinal folding ,,. 'i
'·I
and the flowage of less competent rocks, rather than by faulting. Post-
Precambrian folding has been relative!)' negligible; the characteristic
\; \ 1:)
.: .
Laramide structure is block-faulting developed along northwest- southeast
trend•.
The talc is thought to have been formed in Precambrian time; the
y:
-\It'
••••
high-angle block-faults probably have no significance with regard to the
formation of the talc, but do tend to cornpli cate mining operations.
Tremolite-free talc ore bodies with horizontal widths of mor\ than
ZOO feet, vertical depths of several hundreds of feet, and strike-lengths of.
as much as one-half mile are known in the Ruby Range and the Gravelly
Range. Where dolomite is interbedded with tremolite-free talc in the
Gravelly Range, the scale of this relationship permits the use of
conventional open-pit mining methods with subsequent upgrading by
hand-sorting techniques.
Underground mining has been used in the past, but all current
PFI_BOOK_00005545
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
75-H-320
75-H-320
3
z talc, which is notably tremolite-{ree. This chemical purity and the high
Montana talc-mining operations are on the surface. The hand-sorted ore,
dry-brightness of the ore, plus the homogeneous nature of large surface ore
some o{ which is shipped overseas, is finely ground or micronized in roller
bodies has stimulated much recent interest in locating new sources of Montana
mills and"Cluid-energy mills. The products are distributed both nationwide \
talc. 1
and abroad.
ACKNOWLEDGMENTS i
INTRODUCTION
The wholehearted cooperation, past and present, of the American
OC the aix talc-mining districts in the U.S. only the Allamoore
Talc Company, Cyprus Industrial Minerals Company, the M.P. M. Division
~
district in •estern Texas hae a younger history than that of the southwestern
o{ Pfizer, Inc., and numerous land-owners, particularly Messrs. Fred W.
Montan& t•lc-mi.ning di.etri('L Talc has been mined in southwestern Montana
"Buster" Brown and Art Christensen of Dillon, Montana, is most gratefully ,.
lor some three decadee. aa con1pared with the Gouverneur talc-mining
appreciated and acknowledged. ··'1:·,,.
II
district In northern New York, {or in•tance, where the mining and milling o{
Much of the basic information upon which this paper is constructed ,,..
talc has continued uninterrupted over the past century. 1 ~I
is contained in unpublished graduate dissertations of Dr. Angelo F. Okurna
Montana talc ore:s Oilier fn.nu all uf the other t:.S. '"'"es. cx.:oept for
and Dr. John M. Garihan
2
and the writer baa benefitted greatly from several
\' \ 1:"
local areas In the southern Appalachian Mountains, by having no detectable
field visits made with them Into their areas. Dr. Russell G. Tysdal
3
has been
,,,.
;.,··I:::
.
tremolite (using X-ray di!fraction) and by containing only "trace"' amounts ~; 1: I
so kind as to supply the results of hie investigations in the northernmost ,.
of CaO as ahown in complete chernical analyses. Southwestern Montana is
portion of the Ruby Range.
I 1:
1:
the only locality currently known in North America where such pure, bright-
Messrs. Harold L. James and Kenneth L. Wier and Ms. Karen W. II,,
colored tremolite-free ores may be n11ned in open-pits using today s large
1
Shaw of the U.S. Geological Survey have freely shared much detailed geolog-
II
h
mining machinery. ••
Ical information derived over the years, still largely unpub\ished, within the n
Present ~iontana production iti from six open-pit n1ines: four in the ~,
Christensen Ranch 7. 5' and adjacent quadrangles. They placed much of their
Ruby Ro.nge, one in the Greenhorn Range, and one in the Gravelly Range.
mapping on open-file -- James, Wier, and Shaw
4 in order to aid the work ]·
All of the present production comes out of Madison County, but Beaverhead
I'
,I
of Drs. Okuma and Garihan and of Pfiz;er, Inc. in the course o{ their recent
(I
County has •upplied significant quantities o{ talc ore in the past. Total 11
production in 1974 is estimated at slightly more than ZOO, 000 tons, a figure
investigations into the talc-bearing portions o{ the Ruby Range.
:,,,
Messrs. Tom McGovern and Bennett Owen of Dillon,. Montana, have •
whjch is approximately double that of 1969 - only five years earlier. ,\,, unselfishly shared their knowledge o{ Montana talc and its history, gained over
The recent controversy concerning the purported health- and safety-
the last couple of decades or ao. Both o{ these Cine gentlemen have also proven
hazarde o( trernohte has resulted in aharply increased produ4.:lion o( Montana.
--- ------- ·~····· ------···--~~·------...----·----~-------_.,._..;.;.
PFI_BOOK_00005546
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
75-H-320 75-H-320
5
that arduous and intelligent prospecting, using basic geological principles Ruby Range
and plain common sense, can result in significant new discoveries of talc. The geology of the Ruby Range has been thoroughly studied by
1 2
Mr. Raymond Olson served as a most capable Cield assistant in 1974 Heinrich 5 , Tysdal 3 , Okuma , and Garihan • The work of the last three, all
and made many significant and meaningful contributions to the study. compiled within the past five years, is particularly significant in that between
GEOLOGY them they have mapped the entire range, in addition to conducting detailed
Cons1derably more is known about the geology of the Ruby Range than stratigraphic, structural, and petrolologic investigations. This paper could
about that of the Greenhorn and Cravelly Ranges, but the nature of talc have little significance without having had the previous work of all four of
o..:currencea ia eaoentially the same in all of these and other nearby ranges in
,...
these men to build upon.
aouth ....·eetern Montana. Thrre{ore, even though most of this paper concerns Pre-Bellian marbles in the Ruby Range vary in thickness from less
the Ruby Range, the bulk of ita inforrnation will have pertinence throughout the than 100 feet to more than I, 500 feet. lndividual measured thicknesses, I•
I
••I
remainder of the south\Western Montana talc-mining district. however, are not reliable due to their pronounced tendency toward flowage I,
All of the known cornn1ercial talc in southwestern lviontana occurs in during the intense isoclinal folding of the Precambrian deformational
pre-Beltian dolomitic marLles. Age-dating of other associated geologic units episodes. It is likely that the "normal" thickness of major marble units :\,
-\I
9 . ·'·
ro I 1·
Indicates thai these marble• are on the order of 1.6-3.1 x 10 years old. originally ranged 200-500 feel or so. Amphibolite has commonly been intruded
Amphibolite, calc-sillcate rock, hornblende gneiss, magnetite schist, n1eta- in generally concordant fashion. The major intrusive event, however, was
)L
quartzite, and mica schi6t are all closely associated with the dolomitic n1arbles. the emplacement of the Dillon Granite Gneiss -- a large tabular intrusive
/ 1:
I'
All pre- Belli an rods are intensely isoclinally folded with steep to body of batholithic proportion which is in regional concordance with t.he 1:
,.
I
vertical lin1bs. All those who have worked in the area recognize multiple enclosing rocks. The youngest Precambrian event is thought to have been the
stages of folding, but disagree upon the number of separate deformational Intrusion of vertical to aubvertical diabase dikes emplacedlalong major ~ones
episodes. This folding predated the Paleozoic, as evidenced by the complete of structural weakness, i.e. linear faults in the N-NW octant. The Ruby
absence of such deformation in Can1brian and younger rocks in the northern Range has undergone at least one stage of high-grade (upper amphibolite)
third of the Ruby Range and in other areas. Laramide deformation was regional metamorphism, which must have been initiated at least as early as
mainly block-faulting and the local rotation of fault blocks; the major structures the early otages of intrusion of the Dillon Granite Gneiss (i, e. on the order of
are a set of NW· NNW master faults, along which lateral displacements on the I. 5-2. 0 x 10 9 years or eo ago). This event was followed by the widespread
order of miles are common. development of a retrograde metamorphic event (greenschist grade) of
unknown absolute, but certainly Precambrian age.
c 4
- 4 0 i#US U W
•• - 4 aep 4
• -4 C&£4 Mli =4 IPS a; a:; a e. , ; ;. ¥4 41 ace _pq;u:,;;paaq;s_.pc;;e
PFI_BOOK_0000554 7
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
' {
j
75-H-320 75-H-320
6
7
No Beltian rocks have ever been recognized and it is extremely chloritized. Numerous high- angle N Z0° W faults have displaced the talc vein
doubtful that they were ever deposited anywhere in the Ruby Range. and its enclosing rocks, always in the right-lateral direction. The character
The northern third of the Ruby Range is predominantly composed of and grade of the talc within individual fault blocks varies greatly from that of
Paleozoic sedimentary units whose aggregate thickness is more than 5, 000 the adjacent fault blocks, suggesting that there has been considerable
feet. ~retaceous and Tertiary rocks are present along the flanks of the range, "jostling" of these blocks along the master NNW fault system. The. talc and
but are relatively minor in volume and importance. hanging-wall waste are blasted and/or ripped, then loaded into trucks by
shovels and front-end loaders. The hanging-wall waste, which formerly was
Talc M1nes - Ruby Range
oimply pushed over the hillslope to the north, is now hauled easterly out of
Allhough there are n1any dozena; of inactive mines, potential future
the mine area to large dump•. The waste:ore ratio has increased from about
min~•. and undev~ioped proopects in the Ruby Range, only lls four presently
3:1 or so to more than 10:1 over only the past eight years, as the open-pit
producing mines will be des.-ribed here. The largest talc mines in the Ruby
mine has been extended rapidly downward. The talc ore is trucked some 30
Ranl)e, aecond in importan,~e in l\.1ontana only to the Yellowstone f\.hne in the
Pfi~er's
\..
miles to Barratts mill, "'here it is washed, picked, crushed, and
Gravelly Range, are all Bituated within a relatively small area in the north-
-I'
finely ground in roller mills and fluid-energy mills. In recent years, Pfizer
central portion of the range between the Left and Middle Forks of Stone Creek_ .
, I
has procured the bulk of their ore lor their Barratts mill !probably more than
;:
Treasure t..tinea: --· The Treasure Chest Mine in NWl se(.·, 14,
90';o) from this single mine,
T. 7 S., R. b W., Madison County, l\.1ontana is Pfizer's prin1ary source of
The Treasure State !\.line, also in );W~ oec. 1-l, hao been totally I
ore for their talc -granding plant at Uarratts Siding on the Union Pacific some
I
inactive for more than a decade- It was mined when the existence of .the I
eight mile• 60uth of Dillon, l\.1ontana, This large tabular body of locally pure I
Treasure Chest deposit was not kno" nand was phased out oi operation when
talc has a strike-length of ;.buut 1,100 feet, a honzontal width of up to 125
the potential of the latter became obdous. '
The Treasure State and the
•teet, and haa been mined for several hundreds of feet duwn·dip in a large
Treasure Chest talc veins are the same geological unit; they are separated
open-pit ..>peration. The tah· and 1ts en<.:J06ing rocks strike essential!;· east-
by a high-angle, right-lateral N Z0° W fault, which the writer has named the
west and dip on the average 55° northerly. All of the talc occurs in dolomitic
Treasure Fault. The southwestern block (i.e. the Treasure State Mine) has
marbles and locally the entire thickness of the marble has been converted to
been relatively upthrown, therefore resulting in its topographic displacement
talc, but more commonly large dolon1itic and siliceous ''horses'' occur
II
ln the downhill direction. Talc, ao exposed in the Treasure State Mine, haa
sporadically within the "talc-zone". The footwall is a dark-colored biotite
a atrlke-length of at least 300-400 feet, a horizontal width of 75-100 feet,
schist and the hanging wall, D1llon Granite Gneiss, has been noticeably
I ! and haa been mined to a down-dip depth of more than 100 feet. The dip o!
I
. ·-·· ---·-·------·- -- --- ------·------· --- ·--------·· ·-- - . ···-·· --- -·- -- --- ··-· -·-- ----- ----- --------~---~
PFI_BOOK_00005548
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
I
"!
!
;
;-:.~-- r ·.·
75-H-320 i·_.,.l·
(.· 75-H-320
~. ;
8 9
"1
. the talc and its enclosing rocks is the same as at the Treasure Chest Mine. talc at the Beaverhead Mine has nowhere been observed to form a large
As is also the case at the Treasure Chest Mine the footwall is a dark- colored homogeneous body without inclusions of foreign rock types. Most of these
biotite schist and the hanging wall is Dillon Granite Gneiss. Large quantities undesirable inclusions are dolomite. Mining operations are complicated by
of high-grade talc ore remain here, but there was a considerable amount of the presence of several NNW faults which have invariably reeul~ed in the
"high-grading" in the last stages of mining; therefore, a new start-up of this right-lateral displacement of the talc and its enclosing rocks, as is the case
open-pit mine would be initially extremely expensivl" due to the large amounts also at the Treasure mines. The Treasure Fault has not been recognized
of hanging-wall waate whlth "'ould have to be removed prior to the mining of here, but It is highly likely that even if it does exte!ld this far south that all
I
the ore. Thio io aho a Pfi1er property. of the Beaverhead Mine lies to the east of it. In the Beaverhead and Tr·~asure
Beaverhead Mine: --- The lleaverhead Mine in NW !SE! sec. 14, mines the best talc Ia generally located adjacent or quite close to the biotite
T. 7 5., R. b W., Madison County, Montana is one of Cyprus Industrial schist (footwall in the Treasure mines and hanging wall in the Beaverhead
Mineral Company's two present sources of Montana talc ore. The geology is Mine), suggesting that the schist may have constituted a permeability barrier
eoaentially the same as that of the Treasure Chest and Treasure State Mines, which locallized or channelized the mineralizing solutions. Cyprus has
except that the hanging-wall rock types are schist and gneiss and the footwall recently installed a pit-sorting facility in the Beaverhead Mine. Such a
measure may soon become necessary for Pfizer at the Treasure Chest Mine.
,..,
rock h dolomitic. These relationships strongly suggest that the Beaverhead
Mine Ia situated on the opposite limb of an i&oclinal !old from that of the Indeed, such pit-sorting facilities should probably have been initiated years
Treoure minco. In the horizontal plane the Beaverhead Mine is only 2, 000 ago, from the standpoint of strict conservation, for huge quantities of talc
./
feet or so southeasterly of the Treasure Chest Mine. The strike of the talc ore are contained in the spoils piles of both Treasure mines -- but this talc
and it& enclooing rocks is essentially east-west and dips range 35°-70°
'' is now so hopelessly intermixed with footwall and hanging-wall waste that it
northerly, probably averaging 45°. Tak has been developed over some 800 is probably completely unrecoverable. Talc ore from the f\eaverhead Mine ie
feet of strike-length and has horizontal widths ranging from Z5 feet to 100 trucked some 25 miles down the Cottonwood Creek drainage on the eastern
feet, probably averaging close to 75 feet. At the time of the writer's last flank of the range to a washing and loading facility at Alder, Montana, which
visit, mining had been pursued to a down-dip depth of considerably more than is the terminus of a Burlington Northern spur. From Alder the crude is
100 feet. Mining is done by open-pit methods, which is more difficult and shipped to Cyprus' mills in Three Forks, Montana, Grand Island, Nebraska,
costly here, where the vein dips into a steep hillslope, than at the Treasllre or Ghent, Belgium.
mines, where the vein dips slightly more &teeply than, but in the same .~ Regal (Keystone) Mine: --- The Regal (Keystone) Mine in Ni sec. Z,
direction as the hillalope. Unlike the local oituation at the Treasure mines, T. 8 S., R. 7 W., Madison County, Montana may well be the largest single
'
I
J
........., sw ........ $US u IS PC QQZ$
. ;
•
PFI_BOOK_00005552
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020
NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023
.,
.I
75-H-320
16
z. Garihan, J. M., "Geology and Talc Deposits of the Central Ruby Range,
Madison County, Montana," unpubl. PhD dissertation, The Pennsylvania
State University, 1973, pp. Z09.
3. 1'y•dal, R. G., "Geology of the NorthEnd of the RuLy Range,
Southwestern Montana, •• unpubl. PhD dissertation, University of Montana,
1970, pp. 187.
4. James, H. L., Wier, K. L., and Shaw, K. W., "Map showing lithology
of Precambrian rocks in the Christensen Ran'ch and adjacent quadrangles,
Madia on and Beaverhead Countieo, Montana," U.S. Geol. Survey Open
File Report !unedited field mapl, 191.9.
s. Heinrich, E. W,, "Geology ol the Ruby Mountains and nearby area• in
South-.·estern l\.1ontana, '' Part Z in "Pre-Beltian Geology o( the Cherry
11
Creek and Ruby "-tuu.ncaina
Preview
FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 EXHIBIT 81 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 : i I{ THE GEOLOGY OF MONTANA TALC DEPOSITS ~~ I!·' by Richard H. Olson 1;: ABSTRACT \r ..r, J! ; Talc deposits in the Precambrian of southwestern Montana ;i.. (Beaverhead and Madison Counties) are unique within the U.S. A. in that p:· ; IC large bodies of tremolite-free talc can be open-pit mined. All known /, :; I> deposits are in pre- Beltian dolomite units. The origin is suspected to be : ~~ metasomatic, with the siliceous component having been contributed by an intrusive Precambrian granite gneiss. Precambrian deformation was ,, •• ' t. it.. ; { il.: t extreme and is characterized by multiple periods of tight isoclinal folding ,,. 'i '·I and the flowage of less competent rocks, rather than by faulting. Post- Precambrian folding has been relative!)' negligible; the characteristic \; \ 1:) .: . Laramide structure is block-faulting developed along northwest- southeast trend•. The talc is thought to have been formed in Precambrian time; the y: -\It' •••• high-angle block-faults probably have no significance with regard to the formation of the talc, but do tend to cornpli cate mining operations. Tremolite-free talc ore bodies with horizontal widths of mor\ than ZOO feet, vertical depths of several hundreds of feet, and strike-lengths of. as much as one-half mile are known in the Ruby Range and the Gravelly Range. Where dolomite is interbedded with tremolite-free talc in the Gravelly Range, the scale of this relationship permits the use of conventional open-pit mining methods with subsequent upgrading by hand-sorting techniques. Underground mining has been used in the past, but all current PFI_BOOK_00005545 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 75-H-320 75-H-320 3 z talc, which is notably tremolite-{ree. This chemical purity and the high Montana talc-mining operations are on the surface. The hand-sorted ore, dry-brightness of the ore, plus the homogeneous nature of large surface ore some o{ which is shipped overseas, is finely ground or micronized in roller bodies has stimulated much recent interest in locating new sources of Montana mills and"Cluid-energy mills. The products are distributed both nationwide \ talc. 1 and abroad. ACKNOWLEDGMENTS i INTRODUCTION The wholehearted cooperation, past and present, of the American OC the aix talc-mining districts in the U.S. only the Allamoore Talc Company, Cyprus Industrial Minerals Company, the M.P. M. Division ~ district in •estern Texas hae a younger history than that of the southwestern o{ Pfizer, Inc., and numerous land-owners, particularly Messrs. Fred W. Montan& t•lc-mi.ning di.etri('L Talc has been mined in southwestern Montana "Buster" Brown and Art Christensen of Dillon, Montana, is most gratefully ,. lor some three decadee. aa con1pared with the Gouverneur talc-mining appreciated and acknowledged. ··'1:·,,. II district In northern New York, {or in•tance, where the mining and milling o{ Much of the basic information upon which this paper is constructed ,,.. talc has continued uninterrupted over the past century. 1 ~I is contained in unpublished graduate dissertations of Dr. Angelo F. Okurna Montana talc ore:s Oilier fn.nu all uf the other t:.S. '"'"es. cx.:oept for and Dr. John M. Garihan 2 and the writer baa benefitted greatly from several \' \ 1:" local areas In the southern Appalachian Mountains, by having no detectable field visits made with them Into their areas. Dr. Russell G. Tysdal 3 has been ,,,. ;.,··I::: . tremolite (using X-ray di!fraction) and by containing only "trace"' amounts ~; 1: I so kind as to supply the results of hie investigations in the northernmost ,. of CaO as ahown in complete chernical analyses. Southwestern Montana is portion of the Ruby Range. I 1: 1: the only locality currently known in North America where such pure, bright- Messrs. Harold L. James and Kenneth L. Wier and Ms. Karen W. II,, colored tremolite-free ores may be n11ned in open-pits using today s large 1 Shaw of the U.S. Geological Survey have freely shared much detailed geolog- II h mining machinery. •• Ical information derived over the years, still largely unpub\ished, within the n Present ~iontana production iti from six open-pit n1ines: four in the ~, Christensen Ranch 7. 5' and adjacent quadrangles. They placed much of their Ruby Ro.nge, one in the Greenhorn Range, and one in the Gravelly Range. mapping on open-file -- James, Wier, and Shaw 4 in order to aid the work ]· All of the present production comes out of Madison County, but Beaverhead I' ,I of Drs. Okuma and Garihan and of Pfiz;er, Inc. in the course o{ their recent (I County has •upplied significant quantities o{ talc ore in the past. Total 11 production in 1974 is estimated at slightly more than ZOO, 000 tons, a figure investigations into the talc-bearing portions o{ the Ruby Range. :,,, Messrs. Tom McGovern and Bennett Owen of Dillon,. Montana, have • whjch is approximately double that of 1969 - only five years earlier. ,\,, unselfishly shared their knowledge o{ Montana talc and its history, gained over The recent controversy concerning the purported health- and safety- the last couple of decades or ao. Both o{ these Cine gentlemen have also proven hazarde o( trernohte has resulted in aharply increased produ4.:lion o( Montana. --- ------- ·~····· ------···--~~·------...----·----~-------_.,._..;.;. PFI_BOOK_00005546 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 75-H-320 75-H-320 5 that arduous and intelligent prospecting, using basic geological principles Ruby Range and plain common sense, can result in significant new discoveries of talc. The geology of the Ruby Range has been thoroughly studied by 1 2 Mr. Raymond Olson served as a most capable Cield assistant in 1974 Heinrich 5 , Tysdal 3 , Okuma , and Garihan • The work of the last three, all and made many significant and meaningful contributions to the study. compiled within the past five years, is particularly significant in that between GEOLOGY them they have mapped the entire range, in addition to conducting detailed Cons1derably more is known about the geology of the Ruby Range than stratigraphic, structural, and petrolologic investigations. This paper could about that of the Greenhorn and Cravelly Ranges, but the nature of talc have little significance without having had the previous work of all four of o..:currencea ia eaoentially the same in all of these and other nearby ranges in ,... these men to build upon. aouth ....·eetern Montana. Thrre{ore, even though most of this paper concerns Pre-Bellian marbles in the Ruby Range vary in thickness from less the Ruby Range, the bulk of ita inforrnation will have pertinence throughout the than 100 feet to more than I, 500 feet. lndividual measured thicknesses, I• I ••I remainder of the south\Western Montana talc-mining district. however, are not reliable due to their pronounced tendency toward flowage I, All of the known cornn1ercial talc in southwestern lviontana occurs in during the intense isoclinal folding of the Precambrian deformational pre-Beltian dolomitic marLles. Age-dating of other associated geologic units episodes. It is likely that the "normal" thickness of major marble units :\, -\I 9 . ·'· ro I 1· Indicates thai these marble• are on the order of 1.6-3.1 x 10 years old. originally ranged 200-500 feel or so. Amphibolite has commonly been intruded Amphibolite, calc-sillcate rock, hornblende gneiss, magnetite schist, n1eta- in generally concordant fashion. The major intrusive event, however, was )L quartzite, and mica schi6t are all closely associated with the dolomitic n1arbles. the emplacement of the Dillon Granite Gneiss -- a large tabular intrusive / 1: I' All pre- Belli an rods are intensely isoclinally folded with steep to body of batholithic proportion which is in regional concordance with t.he 1: ,. I vertical lin1bs. All those who have worked in the area recognize multiple enclosing rocks. The youngest Precambrian event is thought to have been the stages of folding, but disagree upon the number of separate deformational Intrusion of vertical to aubvertical diabase dikes emplacedlalong major ~ones episodes. This folding predated the Paleozoic, as evidenced by the complete of structural weakness, i.e. linear faults in the N-NW octant. The Ruby absence of such deformation in Can1brian and younger rocks in the northern Range has undergone at least one stage of high-grade (upper amphibolite) third of the Ruby Range and in other areas. Laramide deformation was regional metamorphism, which must have been initiated at least as early as mainly block-faulting and the local rotation of fault blocks; the major structures the early otages of intrusion of the Dillon Granite Gneiss (i, e. on the order of are a set of NW· NNW master faults, along which lateral displacements on the I. 5-2. 0 x 10 9 years or eo ago). This event was followed by the widespread order of miles are common. development of a retrograde metamorphic event (greenschist grade) of unknown absolute, but certainly Precambrian age. c 4 - 4 0 i#US U W •• - 4 aep 4 • -4 C&£4 Mli =4 IPS a; a:; a e. , ; ;. ¥4 41 ace _pq;u:,;;paaq;s_.pc;;e PFI_BOOK_0000554 7 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 ' { j 75-H-320 75-H-320 6 7 No Beltian rocks have ever been recognized and it is extremely chloritized. Numerous high- angle N Z0° W faults have displaced the talc vein doubtful that they were ever deposited anywhere in the Ruby Range. and its enclosing rocks, always in the right-lateral direction. The character The northern third of the Ruby Range is predominantly composed of and grade of the talc within individual fault blocks varies greatly from that of Paleozoic sedimentary units whose aggregate thickness is more than 5, 000 the adjacent fault blocks, suggesting that there has been considerable feet. ~retaceous and Tertiary rocks are present along the flanks of the range, "jostling" of these blocks along the master NNW fault system. The. talc and but are relatively minor in volume and importance. hanging-wall waste are blasted and/or ripped, then loaded into trucks by shovels and front-end loaders. The hanging-wall waste, which formerly was Talc M1nes - Ruby Range oimply pushed over the hillslope to the north, is now hauled easterly out of Allhough there are n1any dozena; of inactive mines, potential future the mine area to large dump•. The waste:ore ratio has increased from about min~•. and undev~ioped proopects in the Ruby Range, only lls four presently 3:1 or so to more than 10:1 over only the past eight years, as the open-pit producing mines will be des.-ribed here. The largest talc mines in the Ruby mine has been extended rapidly downward. The talc ore is trucked some 30 Ranl)e, aecond in importan,~e in l\.1ontana only to the Yellowstone f\.hne in the Pfi~er's \.. miles to Barratts mill, "'here it is washed, picked, crushed, and Gravelly Range, are all Bituated within a relatively small area in the north- -I' finely ground in roller mills and fluid-energy mills. In recent years, Pfizer central portion of the range between the Left and Middle Forks of Stone Creek_ . , I has procured the bulk of their ore lor their Barratts mill !probably more than ;: Treasure t..tinea: --· The Treasure Chest Mine in NWl se(.·, 14, 90';o) from this single mine, T. 7 S., R. b W., Madison County, l\.1ontana is Pfizer's prin1ary source of The Treasure State !\.line, also in );W~ oec. 1-l, hao been totally I ore for their talc -granding plant at Uarratts Siding on the Union Pacific some I inactive for more than a decade- It was mined when the existence of .the I eight mile• 60uth of Dillon, l\.1ontana, This large tabular body of locally pure I Treasure Chest deposit was not kno" nand was phased out oi operation when talc has a strike-length of ;.buut 1,100 feet, a honzontal width of up to 125 the potential of the latter became obdous. ' The Treasure State and the •teet, and haa been mined for several hundreds of feet duwn·dip in a large Treasure Chest talc veins are the same geological unit; they are separated open-pit ..>peration. The tah· and 1ts en<.:J06ing rocks strike essential!;· east- by a high-angle, right-lateral N Z0° W fault, which the writer has named the west and dip on the average 55° northerly. All of the talc occurs in dolomitic Treasure Fault. The southwestern block (i.e. the Treasure State Mine) has marbles and locally the entire thickness of the marble has been converted to been relatively upthrown, therefore resulting in its topographic displacement talc, but more commonly large dolon1itic and siliceous ''horses'' occur II ln the downhill direction. Talc, ao exposed in the Treasure State Mine, haa sporadically within the "talc-zone". The footwall is a dark-colored biotite a atrlke-length of at least 300-400 feet, a horizontal width of 75-100 feet, schist and the hanging wall, D1llon Granite Gneiss, has been noticeably I ! and haa been mined to a down-dip depth of more than 100 feet. The dip o! I . ·-·· ---·-·------·- -- --- ------·------· --- ·--------·· ·-- - . ···-·· --- -·- -- --- ··-· -·-- ----- ----- --------~---~ PFI_BOOK_00005548 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 I "! ! ; ;-:.~-- r ·.· 75-H-320 i·_.,.l· (.· 75-H-320 ~. ; 8 9 "1 . the talc and its enclosing rocks is the same as at the Treasure Chest Mine. talc at the Beaverhead Mine has nowhere been observed to form a large As is also the case at the Treasure Chest Mine the footwall is a dark- colored homogeneous body without inclusions of foreign rock types. Most of these biotite schist and the hanging wall is Dillon Granite Gneiss. Large quantities undesirable inclusions are dolomite. Mining operations are complicated by of high-grade talc ore remain here, but there was a considerable amount of the presence of several NNW faults which have invariably reeul~ed in the "high-grading" in the last stages of mining; therefore, a new start-up of this right-lateral displacement of the talc and its enclosing rocks, as is the case open-pit mine would be initially extremely expensivl" due to the large amounts also at the Treasure mines. The Treasure Fault has not been recognized of hanging-wall waate whlth "'ould have to be removed prior to the mining of here, but It is highly likely that even if it does exte!ld this far south that all I the ore. Thio io aho a Pfi1er property. of the Beaverhead Mine lies to the east of it. In the Beaverhead and Tr·~asure Beaverhead Mine: --- The lleaverhead Mine in NW !SE! sec. 14, mines the best talc Ia generally located adjacent or quite close to the biotite T. 7 5., R. b W., Madison County, Montana is one of Cyprus Industrial schist (footwall in the Treasure mines and hanging wall in the Beaverhead Mineral Company's two present sources of Montana talc ore. The geology is Mine), suggesting that the schist may have constituted a permeability barrier eoaentially the same as that of the Treasure Chest and Treasure State Mines, which locallized or channelized the mineralizing solutions. Cyprus has except that the hanging-wall rock types are schist and gneiss and the footwall recently installed a pit-sorting facility in the Beaverhead Mine. Such a measure may soon become necessary for Pfizer at the Treasure Chest Mine. ,.., rock h dolomitic. These relationships strongly suggest that the Beaverhead Mine Ia situated on the opposite limb of an i&oclinal !old from that of the Indeed, such pit-sorting facilities should probably have been initiated years Treoure minco. In the horizontal plane the Beaverhead Mine is only 2, 000 ago, from the standpoint of strict conservation, for huge quantities of talc ./ feet or so southeasterly of the Treasure Chest Mine. The strike of the talc ore are contained in the spoils piles of both Treasure mines -- but this talc and it& enclooing rocks is essentially east-west and dips range 35°-70° '' is now so hopelessly intermixed with footwall and hanging-wall waste that it northerly, probably averaging 45°. Tak has been developed over some 800 is probably completely unrecoverable. Talc ore from the f\eaverhead Mine ie feet of strike-length and has horizontal widths ranging from Z5 feet to 100 trucked some 25 miles down the Cottonwood Creek drainage on the eastern feet, probably averaging close to 75 feet. At the time of the writer's last flank of the range to a washing and loading facility at Alder, Montana, which visit, mining had been pursued to a down-dip depth of considerably more than is the terminus of a Burlington Northern spur. From Alder the crude is 100 feet. Mining is done by open-pit methods, which is more difficult and shipped to Cyprus' mills in Three Forks, Montana, Grand Island, Nebraska, costly here, where the vein dips into a steep hillslope, than at the Treasllre or Ghent, Belgium. mines, where the vein dips slightly more &teeply than, but in the same .~ Regal (Keystone) Mine: --- The Regal (Keystone) Mine in Ni sec. Z, direction as the hillalope. Unlike the local oituation at the Treasure mines, T. 8 S., R. 7 W., Madison County, Montana may well be the largest single ' I J ........., sw ........ $US u IS PC QQZ$ . ; • PFI_BOOK_00005552 FILED: ERIE COUNTY CLERK 03/17/2023 08:48 PM INDEX NO. 815818/2020 NYSCEF DOC. NO. 290 RECEIVED NYSCEF: 03/17/2023 ., .I 75-H-320 16 z. Garihan, J. M., "Geology and Talc Deposits of the Central Ruby Range, Madison County, Montana," unpubl. PhD dissertation, The Pennsylvania State University, 1973, pp. Z09. 3. 1'y•dal, R. G., "Geology of the NorthEnd of the RuLy Range, Southwestern Montana, •• unpubl. PhD dissertation, University of Montana, 1970, pp. 187. 4. James, H. L., Wier, K. L., and Shaw, K. W., "Map showing lithology of Precambrian rocks in the Christensen Ran'ch and adjacent quadrangles, Madia on and Beaverhead Countieo, Montana," U.S. Geol. Survey Open File Report !unedited field mapl, 191.9. s. Heinrich, E. W,, "Geology ol the Ruby Mountains and nearby area• in South-.·estern l\.1ontana, '' Part Z in "Pre-Beltian Geology o( the Cherry 11 Creek and Ruby "-tuu.ncaina