Stillwater Mining Co. Minn.Adit Prj

Site Name

Primary: Stillwater Mining Co. Minn.Adit Prj
Secondary: J-M Reef Deposit
Secondary: Minneapolis Adit Project
Secondary: Stillwater Mine
Secondary: Johns-Manville Stillwater Platinum
Secondary: Stillwater Platinum Project
Secondary: Stillwater Pgm Resources
Secondary: M Prospect

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Commodity

Primary: PGE
Primary: Platinum
Primary: Palladium
Secondary: Gold
Secondary: Rhodium
Tertiary: Osmium
Tertiary: Iridium
Tertiary: Nickel
Tertiary: Copper
Tertiary: Ruthenium

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Location

State: Montana
County: Stillwater
District: Stillwater

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Land Status

Land ownership: National Forest
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

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Holdings

Type: Patented
Type: Located Claim

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Workings

Not available

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Ownership

Owner Name: Johns-Manville Products Corp.
Company ID: 2401490
Percent: 50.00
Info Year: 1990
Years: 1979 - 1994

Owner Name: Stillwater PGM Resources
Info Year: 1998
Years: 1979 - 1994

Owner Name: Chevron Resources, Inc.
Company ID: 2401490
Percent: 50.00
Info Year: 1990
Years: 1979 - 1994

Owner Name: Stillwater Mining Co.
Company ID: 2401490
Percent: 100.0
Home Office: Montana
Info Year: 1996
Years: 1994 -

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Production

Year: 1995
Description: Palladium Production 169000 Troy Ounces
Year: 1995
Description: Platinum Production 51000 Troy Ounces

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Deposit

Record Type: Site
Operation Category: Producer
Deposit Type: PGE Reef
Plant Type: Beneficiation (Mill)
Plant Subtype: Flotation
Operation Type: Underground
Mining Method: Filled Stopes - Horiz Cut and Fill W/Waste Rock
Milling Method: Flotation
Year First Production: 1986
Discovery Year: 1971
Years of Production:
Organization:
Significant: Y

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Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Middle Rocky Mountains

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Mineral Deposit Model

Model Name: Merensky Reef PGE

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Orebody

Name: J-M Reef
Form: Tabular, stratiform, disseminated

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Structure

Type: L
Structure: Faults

Type: L
Structure: Folds

Type: L
Structure: High-Angle Reverse Faults

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Analytical Data: HOST ROCKS CONTAIN 0.5-1.0% CHALCOPYRITE+PYRRHOTITE+PENTLANDITE WHICH CONTAIN SMALL AMOUNTS OF PLATINUM BEARING SULFIDES. ONE 5.5 KM SEGMENT OF REEF AVERAGES 22.3PPM PT+PD OVER 2.1 M WIDTH. PT:PD=1:3.

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Materials

Ore: Pyrite
Ore: Gold
Ore: Chalcopyrite
Ore: Pentlandite
Ore: Pyrrhotite
Ore: Mackinawite
Ore: Platinum
Ore: Palladium
Gangue: Plagioclase
Gangue: Tremolite
Gangue: Hornblende
Gangue: Magnetite
Gangue: Serpentine
Gangue: Chlorite
Gangue: Sphalerite
Gangue: Apatite
Gangue: Galena
Gangue: Olivine
Gangue: Talc
Unknown: Cubanite
Unknown: Marcasite
Unknown: Silver

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Comments

Comment (Reserve-Resource): PALLADIUM TO PLATINUM GRADE RATIO IS 3.5 TO 1.0 BEFORE PROCESSING AND LOSS OF 10%. PROVEN + PROBABLE ORE RESERVES, EAST BOULDER AREA, 12/31/95.

Comment (Geology): Tectonic Setting At Time Of Emplacement Of The Stillwater Complex Is Unknown. The Complex Was Emplaced Shortly After A Major Regional, Subduction-Related Magmatic Event That Culminated In Emplacement Of The 2.73-2.79 Ga Granitoid Suite In The Batholith Exposed In The Beartooth Uplift (Wooden And Others, 1991). However, There Is No Evidence That The Magmatism That Formed The Stillwater Complex Is Related To Convergent Margin Tectonics And Magmatism

Comment (Geology): Metals May Have Been Derived From Ultramafic Magma And Sulfur From Anorthositic Magma. If So, Sulfides Formed As Magmas Mixed

Comment (Exploration): THE J-M REEF DEPOSITS WERE DISCOVERED BY GEOCHEMICAL SURVEYS IN 1967, BUT THE PRESENCE OF SULFIDES WAS KNOWN IN THE 1930'S

Comment (Geology): THE J-M REEF IS 1-3 M THICK AND HAS BEEN TRACED FOR 40 KM. AGE OF STILLWATER COMPLEX IS 2,705 +/- 4 MA BASED ON U-PB SYSTEMATICS ON ZIRCON-BADDELEYITE (PREMO AND OTHERS, 1990)

Comment (Production): ONLY PRODUCER OF PGE AS PRIMARY COMMODITY IN THE CONTERMINOUS U.S. MINE REACHED MINING CAPACITY OF 1,000 TONS PER DAY IN 1990 FOR AN ANNUAL PRODUCTION RATE OF 50,000 OZ PT AND ABOUT 170,000 OZ PD (update- Boulder Creek on same unit is presently also mining PGE's)

Comment (Reserve-Resource): PALLADIUM TO PLATINUM GRADE RATIO IS 3.5 TO 1.0 BEFORE PROCESSING AND LOSS OF 10%. THESE ARE EAST BOULDER AREA RESERVES.

Comment (Economic Factors): BENEFICIATION STUDIES ARE CURRENTLY (4/81) IN PROGRESS BY RENO METALLURGY RECOVERY OF AU, NI, CU IS VERY LOW WHEN STUDIES ARE COMPLETED, RECOVERIES ARE EXPECTED TO IMPROVE.

Comment (Production): CONCENTRATE WOULD BE SHIPPED TO SUDBURY, ONTARIO, CANADA.

Comment (Reserve-Resource): ALL PLATINUM GROUP ELEMENTS ARE PRESENT AND RECOVERABLE ASSAYS ARE NOT AVAILABLE FOR IR, OS, RU.

Comment (Economic Factors): ESTIMATED DILUTION IS 20%

Comment (Geology): The Stillwater Complex Is Exposed Along The Northern Margin Of The Beartooth Uplift, One Of Several Laramide Basement-Cored Ranges That Make Up The Rocky Mountain Foreland Of South-Central Montana (Foose And Others, 1961: Kulik And Schmidt, 1988)

Comment (Identification): LISTED AS GSC ID # ISM0330 ON THE USGS JUNE 95 LIST UNDER THE NAME OF J-M REEF DEPOSIT. ALSO LISTED AS ISMI-PGE35. OTHER MAS SEQ# 0300970003. RELATED MAS SEQ# 0300970066: POSSIBLY TO 0300970031. THE STILLWATER PGM SMELTER IT MAY HAVE SOME RELATIONSHIP TO THIS PROPERTY. PREPRODUCTION YEARS BEGINNING IN 1982.

Comment (Workings): Approximately early 1990;s 2 ADITS WITH CROSSCUTS, DRIFTS, RAISES. 4,570+ FT DIAMOND DRILL CORE.

Comment (Geology): J-M REEF IS 400-450 M ABOVE BASE OF BANDED SERIES IN BASAL PART OF ANORTHOSITE I SUBZONE OF TROCTOLITE-ANORTHOSITE ZONE I. THIS COINCIDES WITH REAPPEARANCE OF OLIVINE IN CRYSTALLIZATION SEQUENCE. SULFIDES FORMED AS IMMISCIBLE LIQUID DROPS DURING EARLY STAGES OF REEF FORMATION ALONG WITH OLIVINE. STRUCTURES SIMILAR TO THE POTHOLE STRUCTURES IN THE MERENSKY REEF HAVE BEEN FOUND

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References

Reference (Deposit): MANN, E.L., 1981, EXPLORATION MANAGER-MINING GROUP, JOHNS-MANVILLE CORPORATION: PERSONAL COMMUNICATION.

Reference (Deposit): PASCHALL, TARI. CITIZENS VOICE CONCERN ABOUT SMC EXPANSION. STILLWATER COUNTY NEWS. JUNE 24, 1992.

Reference (Deposit): STILLWATER COUNTY NEWS. SMC MINE EXPANSION NEARING SCHEDULE. JUNE 10, 1992.

Reference (Deposit): GREAT FALLS TRIBUNE. MINE EXPANSION DESCRIBED AS BOTH BOON, THREAT. JAN. 1, 1992.

Reference (Deposit): SEG NEWSLETTER. JAN. 1992, NO. 8, P. 23.

Reference (Deposit): SEG NEWSLETTER. NORTHERN ROCKIES: MONTANA. OCT. 1991, NO. 7. P. 17.

Reference (Deposit): U.S. BUREAU OF MINES, 1981, MINERAL COMMODITY SUMMARIES, PP 114-115.

Reference (Deposit): KILPATRICK, JAMES. MINE IN MONTANA BRINGS UP QUESTION OF ROYALTIES. LIVINGSTON ENTERPRISE. JUNE 29, 1992.

Reference (Deposit): MINING JOURNAL, LONDON, AUG. 8, 1997, VOL. 329, #8441, P128.

Reference (Deposit): THE MINING RECORD, VOL. 108, #9, FEB. 26, 1997, PP. 18,19.

Reference (Deposit): SEGERSTROM, K., AND CARLSON, R.R., U.S.G.S. OPEN FILE REPORTS 77-370, 78-704, 79-656, 80-364.

Reference (Deposit): THE MINING RECORD, VOL., 107, #49, DEC., 4, 1996, P18.

Reference (Deposit): READ, R.F., 1977, MINERAL DEVELOPMENT POTENTIAL OF THE STILLWATER COMPLEX, MONTANA, U.S.B.M. UNPUBLISHED MAS REPORT, 16P.

Reference (Deposit): MILLER, R.W., 1981, PROJECT COORDINATOR, STILLWATER PROJECT, ANACONDA COPPER COMPANY, PERSONAL COMMUNICATION

Reference (Deposit): PAGE, N.J. AND JACKSON,E.D., 1967, PRELIMINARY REPORT ON SULFIDE AND PLATINUM GROUP MINERALS IN THE CHROMITES OF THE STILLWATER COMPLEX, U.S.G.S. PROFRESSIONAL PAPER 575-D, PP D-123 - D-126.

Reference (Deposit): CHADWICK, J.R., 1980, IMPALA PLATINUM PREPARING TO PASS 1,000,000 OUNCES YEARLY, MINING WORLD, VOL 33, NO. 12, 5P.

Reference (Deposit): BENNETTS, J., MORRICE, E., AND WONG, M.M., 1981, PREPARATION OF PLATINUM-PALLADIUM FLOTATION CONCENTRATE FROM STILLWATER COMPLEX ORE, U.S.B.M. RI 8500.

Reference (Reserve-Resource): THE MINING RECORD, VOL. 108, #9, FEB. 26, 1997, PP. 18, 19.

Reference (Reserve-Resource): MONT. BUREAU OF MINES AND GEOL. BULLETIN 129, 1991, 1:500,000 SCALE.

Reference (Reserve-Resource): STILLWATER MINING COMPANY 1995 ANNUAL REPORT, PP. 13, 30.

Reference (Geology): Czamanske, G.K., and Zientek, M.L., technical editors, 1985, The Stillwater Complex, Montana: Geology and guide: Montana Bureau of Mines and Geology Special Publication 92, 396 p.

Reference (Production): COOMBES, J.S., 1990, PLATINUM 1990: JOHNSON MATTHEY, P. 18.

Reference (Geology): BOW, C., WOLFGRAM, D., TURNER, A., BARNES, S., EVANS, J., ZDEPSKI, M., AND BOUDREAU, A., 1982, INVESTIGATIONS OF THE HOWLAND REEF OF THE STILLWATER COMPLEX, MINNEAPOLIS ADIT AREA: STRATIGRAPHY, STRUCTURE, AND MINERALIZATION: ECONOMIC GEOLOGY, V. 77, P. 1481-1492.

Reference (Geology): TODD, S.G., KEITH, D.W., LE ROY, L.W., SCHISSEL, D.J., MANN, E.L., AND IRVINE, T.N., 1982, THE J-M PLATINUM-PALLADIUM REEF OF THE STILLWATER COMPLEX, MONTANA: I. STRATIGRAPHY AND PETROLOGY: ECONOMIC GEOLOGY, V. 77, P. 1454-1480.

Reference (General): ZIENTEK, M.L., 1993, MINERAL RESOURCE APPRAISAL FOR LOCATABLE MINERALS: THE STILLWATER COMPLEX, IN HAMMARSTROM, J.M., ZIENTEK, M.L., AND ELLIOTT, J.E., EDS., MINERAL RESOURCE ASSESSMENT OF THE ABSAROKA-BEARTOOTH STUDY AREA, CUSTER AND GALLATIN NATIONAL FORESTS, MONTANA: U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 93-207, P. F1-F83.

Reference (Reserve-Resource): STILLWATER MINING COMPANY 1994 ANNUAL REPORT, P10.

Reference (Deposit): STILLWATER PGM RESOURCES, 1980, INITIAL PLAN OF OPERATIONS FOR POSSIBLE FUTURE MINING ACTIVITY BY STILLWATER PGM RESOURCES IN SWEET GRASS COUNTY, STILLWATER COMPLEX, MONTANA, 18P, 2 ILLUSTRATIONS.

Reference (Deposit): SJOBERG, J., 1981, GEOLOGIST, U.S.B.M. RENO RESEARCH CENTER: PERSONAL COMMUNICATION.

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Principal Gold Districts of Montana

In Montana, 54 mining districts have each have produced more than 10,000 ounces of gold. The largest producers are Butte, Helena, Marysville, and Virginia City, each having produced more than one million ounces. Twenty seven other districts are each credited with between 100,000 and one million ounces of gold production. Read more: Principal Gold Districts of Montana.