Mouat Ni-Cu South

Site Name

Primary: Mouat Ni-Cu South
Secondary: South Mouat Area

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Commodity

Primary: Nickel
Primary: Copper
Secondary: Cobalt
Tertiary: Silver
Tertiary: Gold
Tertiary: PGE

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Location

State: Montana
County: Stillwater
District: In Stillwater Complex

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Land Status

Land ownership: Private
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

Not available

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Workings

Not available

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Ownership

Owner Name: Anaconda Co.
Years: 1970 -

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Discovery Year: 1967
Years of Production:
Organization:
Significant: N
Deposit Size: S

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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: Stillwater Ni-Cu

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Orebody

Form: LENTICULAR TO TABULAR CONCENTRATIONS OF SUFLIDE MINERALS

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Structure

Type: R
Description: 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)

Type: L
Description: See Deposit Description

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Alterations

Alteration Type: L
Alteration Text: None Related To The Ore-Forming Process

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Rocks

Not available

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Analytical Data

Analytical Data: NET-TEXTURED ORE PT=4.2 (49), PD=14.5 (130), RH=1 (9)
Analytical Data: NET-TEXTURED ORE PT=3.3 (62), PD=13 (83), RH=8.1 (18). STILLWATER-ASSOCIATED SILLS AND DIKES (MAFIC NORITE): DISSEMINATED ORE PT=7.55 (24), PD=7.5 (18), RH=0.6 (7)
Analytical Data: UNPUB DATA): BASAL SERIES: DISSEMINATED ORE PT=7.15 (140), PD=15 (78), RH=1 (2)
Analytical Data: ZIENTEK, 1993
Analytical Data: SEE RESERVE/RESOURCE DATA. MEDIAN (AND MAXIMUM) PT, PD, AND RH CONTENTS IN PPB OF DIFFERENT ORE TYPES WITHIN THE MOUAT DEPOSIT (ZIENTEK AND OTHERS, 1986
Analytical Data: MASSIVE ORE PT=3.05 (150), PD=22 (410), RH=1.3 (9). STILLWATER-ASSOCIATED SILLS AND DIKES (GABBRONORITE): DISSEMINATED ORE PT=5.0 (960), PD=9.2 (340), RH=0.8 (5).

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Materials

Ore: Pentlandite
Ore: Pyrrhotite
Ore: Chalcopyrite
Gangue: Magnetite
Gangue: Olivine
Gangue: Plagioclase

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Comments

Comment (Deposit): METALLURGICAL STUDIES BY ANACONDA INDICATED THAT BULK SULFIDE FLOTATION PRODUCED A LOW-GRADE CONCENTRATE WITH GOOD RECOVERY; HOWEVER, THIS CONCENTRATE WAS UNSUITABLE FOR SMELTER FEED AND WAS THEREFORE UNSALABLE. A LARGE PROPORTION OF THE NI IS ASSOCIATED WITH PYRRHOTITE, EITHER IN SOLID SOLUTION OR AS FLAME EXSOLUTION OF PENTLANDITE IN PYRRHOTITE. ; INFO.SRC : 1 PUB LIT; 2 UNPUB REPT

Comment (Workings): THERE ARE NO WORKINGS IN THE PART OF THE MOUAT DEPOSIT SOUTH OF VERDIGRIS CREEK

Comment (Geology): AGE OF STILLWATER COMPLEX IS 2,705 =/- 4 MA BASED ON U-PB SYSTEMATICS ON ZIRCON-BADDELEYITE (PREMO AND OTHERS, 1991)

Comment (Production): NO PRODUCTION

Comment (Deposit): ORE CONSISTS OF DISSEMINATED, MATRIX, AND MASSIVE CONCENTRATIONS OF MAGMATIC SULFIDES IN LENSES AND TABULAR BODIES IN MAFIC AND ULTRAMAFIC INTRUSIONS NEAR THE MARGIN OF THE STILLWATER COMPLEX. SULFIDE MINERALIZATION THAT CONSTITUTES THE MOUAT DEPOSIT LIES NEAR THE BASE OF THE STILLWATER COMPLEX WEST OF THE STILLWATER RIVER. THE HOST ROCKS LIE BETWEEN TWO SOUTH-DIPPING, HIGH-ANGLE REVERSE FAULTS, THE LAKE FAULT ON THE NORTH AND THE BLUEBIRD THRUST ON THE SOUTH. LAYERED ROCKS OF THE STILLWATER COMPLEX ARE FOLDED INTO A BROAD SYNCLINE BETWEEN THESE TWO FAULTA AND, IN THE AREA OF THE CU-NI SULFIDE DEPOSITS, GENERALLY DIP 60 DEGREES NORTHWEST. BETWEEN THE TWO HIGH-ANGLE REVERSE FAULTS, THE DEPOSIT IS CUT BY AN OLDER SET OF FAULTS THAT STRIKE NORTHEAST AND HAVE NEAR VERTICAL DIPS AND A YOUNDER SET OF NORTHWEST-STRIKING, NEAR VERTICAL FAULTS THAT SHOW LEFT-LATERAL DISPLACEMENT. THE MOUAT DEPOSIT CAN BE SUBDIVIDED INTO TWO PARTS, A NORTHERN BLOCK THAT LIES NORTH OF VERDIGRIS CREEK (SEE

Comment (Deposit): RECORD M060102) AND A SOUTHERN PART THAT LIES SOUTH OF VERDIGRIS CREEK (THIS RECORD). MINERALIZED ROCKS SOUTH OF VERDIGRIS CREEK ARE ALMOST COMPLETELY COVERED BY GLACIAL DEPOSITS; DRILLING HAS SHOWN THAT SULFIDE MINERALIZATION OCCURS BOTH IN THE BASAL SERIES (AND TO A LESSER EXTENT THE PERIDOTITE ZONE) OF THE STILLWATER COMPLEX AND IN STILLWATER-ASSOCIATED SILLS AND DIKES THAT INTRUDE THE METAMORPHOSED SEDIMENTARY ROCKS BELOW THE BASE OF THE STILLWATER COMPLEX. THE MINERALIZED SILLS AND DIKES ARE LESS COMMON AND ARE SMALLER THAN THOSE IN THE AREA NORTH OF VERDIGRIS CREEK. SEE PAGE AND OTHERS (1985A), PAGE AND NOKLEBERG (1974), ZIENTEK AND OTHERS (1989).

Comment (Development): THIS PART OF ORE EXTENSION OF THE MOUAT DEPOSIT WAS NOT DISCOVERED UNTIL 1967. EXPLORATION HISTORY IS SUMMARIZED IN PAGE AND OTHERS (1985B) AND OTHER SOURCES CITED BELOW. MINERALIZATION IN THE MOUAT DEPOSIT NORTH OF VERDIGRIS CRFEEK WAS DISCOVERED IN 1883 AND ALL EXPLORATION AND DEVELOPMENT WORK FOCUSSED ON THAT PART OF THE DEPOSIT. IT WAS NOT UNTIL THE 1960'S WHEN ANACONDA DECIDED TO RE-EVALUATE THE MOUAT AND ADJACENT AREAS FOR LARGE-TONNAGE LOW-GRADE DEPOSITS OF NI-CU ORE, THAT WORK BEGAN IN THE SOUTH MOUAT AREA. INITIAL STUDIES BEGAN IN 1966; FULL-SCALE PROJECT WORK CONCENTRATING ON THE MOUAT AREA BEGAN IN MAY, 1967. THIS WORK EXTENDED THE AREA OF KNOWN MINERALIZATION TO THE SOUTH MOUAT AREA AND IDENTIFIED SEVERAL LARGE ANOMALOUS ZONES IN ADJACENT AREAS (GEOCHEMISTRY AND GEOPHYSICS). DRILLING IN THE MOUAT AREA BEGAN IN SEPT. 1967. BY OCT. 1970, WHEN EXPLORATORY AND DEVELOPMENT DRILLING WAS CURTAILED, APPROX. 92,0401 FT OF CORE FROM 95 HOLES HAD BEEN DRILLED IN THE MOUAT AREA

Comment (Development): (BOTH THE VERDIGRIS CREEK AND SOUTH MOUAT AREAS). ALTHOUGH WORK CONTINUED SPORADICALLY IN THE VERDIGRIS CREEK AREA, NO WORK HAS BEEN DONE ON THE SOUTH MOUAT AREA SINCE 1970.

Comment (Commodity): ANACONDA DID NOT ROUTINELY ANALYZE FOR METALS OTHER THAN CU AND NI

Comment (Reserve-Resource): RESOURCES BASED UPON EXPLORATION AND DEVELOPMENT DRILLING BY ANACONDA UP TO 1978 FOR THE ENTIRE MOUAT DEPOSIT (INCLUDES THE AREAS NORTH AND SOUTH OF VERDIGRIS CREEK. SEE ZINETEK (1993) FOR SUMMARY OF ADDITIONAL RESOURCE INFORMATION GENERATED BY ANACONDA (DIFFERENT CUT-OFF). NOTE ON RESOURCE CALCULATION: FROM 1967-1970, ANACONDA DRILLED THE MOUAT DEPOSIT ON 200 FT CENTERS AND USED A CORSS-SECTION METHOD TO CALCULATE RESOURCES. IN THE MID-1980'S, THE USGS UNSUCCESSFULLY ATTEMPTED TO STATISTICALLY ESTIMATE IN-SITU ORE RESERVES BY THE KRIGING TECHNIQUE; THE DRILL SPACING WAS NOT APPROPRIATE GIVEN THE COMPLEX DISTRIBUTION OF THE ORE.

Comment (Location): UNSURVEYED

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References

Reference (Deposit): PAGE, N.J, ZIENTEK, M.L., LIPIN, B.R., MANN, E.L. (BOB), SCHMIDT, E.A., TURNER, A.R., CZAMANSKE, G.K., AND RAEDEKE, L.D., 1985B, EXPLORATION AND MINING HISTORY OF THE STILLWATER COMPLEX AND ADJACENT ROCKS, IN CZAMANSKE, G.K., AND ZIENTEK, M.L., EDS., THE STILLWATER COMPLEX, MONTANA: GEOLOGY AND GUIDE: MONTANA BUREAU OF MINES AND GEOLOGY SPECIAL PUBLICATIONS 92, P. 77-92.

Reference (Deposit): PAGE, N.J, ZIENTEK, M.L., LIPIN, B.R., RAEDEKE, L.D., WOODEN, J.L., TURNER, A.R., LOFERSKI, P.J., FOOSE, M.P., MORING, B.C., AND RYAN, M.P., 1985A, GEOLOGY OF THE STILLWATER COMPLEX EXPOSED IN THE MOUNTAIN VIEW AREA AND ON THE WEST SIDE OF THE STILLWATER CANYON, IN CZAMANSKE, G.K., AND ZIENTEK, M.L., EDS., THE STILLWATER COMPLEX, MONTANA: GEOLOGY AND GUIDE: MONTANA BUREAU OF MINES AND GEOLOGY SPECIAL PUBLICATION 92, P. 147-209.

Reference (Deposit): WOODEN, J.L., CZAMANSKE, G.K., AND ZIENTEK, M.L., 1991, A LEAD ISOTOPIC STUDY OF THE STILLWATER COMPLEX, MONTANA: CONSTRAINTS ON CRUSTAL CONTAMINATION AND SOURCE REGIONS: CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, V. 107, P. 80-93.

Reference (Deposit): ZIENTEK, M.L., AND RIPLEY, E.M., 1990, SULFUR ISOTOPIC STUDIES OF THE STILLWATER COMPLEX AND ASSOCIATED ROCKS, MONTANA: ECONOMIC GEOLOGY, V. 85, P. 376-391.

Reference (Reserve-Resource): SOUTH MOUAT AREA RESOURCE ESTIMATES ARE FROM ATTANASI AND BAWIEC (1987) AND WERE MADE ON TWO DOMAINS; THE FIRST FOUR ESTIMATES ABOVE FROM ONE DOMAIN AND THE LAST OUR FROM THE OTHER DOMAIN

Reference (Deposit): ATTANASI, E.D., AND BAWIEC, W.J., 1987, A RESOURCE ASSESSMENT OF COPPER AND NICKEL SULFIDES WITHIN THE MOUNTAIN VIEW AREA, STILLWATER COMPLEX, MONTANA: U.S. GEOLOGICAL SURVEY BULLETIN 1674B, 29 P.

Reference (Deposit): PAGE, N.J, 1979, STILLWATR COMPLEX, MONTANA - STRUCTURE, MINERALOGY, AND PETROLOGY OF THE BASAL ZONE WITH EMPHASIS ON THE OCCURRENCE OF SULFIDES: U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1938, 69 P.

Reference (Deposit): PREMO, W.R., HELZ, R.T., ZIENTEK, M.L., AND LANGSTON, R.B., 1990, U-PB AND SM-ND AGES FOR THE STILLWATER COMPLEX AND ITS ASSOCIATED SILLS AND DIKES, BEARTOOTH MOUNTAINS, MONTANA: IDENTIFICATION OF A PARENT MAGMA?: GEOLOGY, V. 18, P. 1065-1068.

Reference (Deposit): PAGE, N.J, AND NOKLEBERG, W.J., 1974, GEOLOGIC MAP OF THE STILLWATER COMPLEX, MONTANA: U.S. GEOLOGICAL SURVEY MISCELLANEOUS GEOLOGIC INVESTIGATIONS SERIES MAP I-797, 5 SHEETS, SCALE 1:12,000.

Reference (Deposit): ZIENTEK, M.L., BAWIEC, W.J., PAGE, N.J, AND COOPER, R.W., 1989, MAPS, SECTIONS, AND STRUCTURE-CONTOUR PERSPECTIVE DIAGRAMS SHOWING THE GEOLOGY AND GEOCHEMISTRY OF THE MOUAT NICKEL-COPPER PROSPECT, STILLWATER COMPLEX, STILLWATER COUNTY, MONTANA: U.S. GEOLOGICAL SURVEY MISCELLANEOUS FIELD STUDIES MAP MF-2038, 2 SHEETS, SCALE 1:24,000.

Reference (Deposit): ZINETEK, 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 ABASROKA-BEARTOOTH STUDY AREA, CUSTER AND GALLATIN NATIONAL FORESTS, MONTANA: U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 93-207, P. F1-F83.

Reference (Deposit): ZIENTEK, M.L., FOOSE, M.P., AND MEI, LEUNG, 1986, PALLADIUM, PLATINUM, AND RHODIUM CONTENTS OF ROCKS NEAR THE LOWER MARGIN OF THE STILLWATER COMPLEX, MONTANA: ECONOMIC GEOLOGY, V. 81, P. 1169-1178.

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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.