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Mouat Ni-Cu South

Occurrence in Stillwater county in Montana, United States with commodities Nickel, Copper, Cobalt, PGE, Silver, Gold
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Land status
  17. Ownership information
  18. Reserves and resources
  19. Links to other databases
  20. Bibliographic references
  21. General comments
  22. Reporter information

Geologic information

Identification information

Deposit ID 10048658
MRDS ID MP00270
Record type Site
Current site name Mouat Ni-Cu South
Alternate or previous names South Mouat Area

Geographic coordinates

Geographic coordinates: -109.89996, 45.37686 (WGS84)
Elevation 2042
Relative position ABOUT 0.6 MI SOUTH OF MOUNTAIN VIEW LAKE

Site location context

Political divisions (FIPS codes)

Stillwater(county)

Montana(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Meyer Mountain(quadrangle 1:24,000 scale)

Red Lodge(quadrangle 1:100,000 scale)

Billings(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Stillwater(hydrologic unit)

Upper Yellowstone(hydrologic accounting unit)

Upper Yellowstone(hydrologic subregion)

Missouri(hydrologic region)

Federal lands

Custer Gallatin National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Montana Stillwater

Comments on the location information

  • UNSURVEYED

Commodities

Commodity Importance
Nickel Critical Primary
Copper Primary
Cobalt Critical Secondary
PGE Critical Tertiary
Silver Tertiary
Gold Tertiary

Comments on the commodity information

  • ANACONDA DID NOT ROUTINELY ANALYZE FOR METALS OTHER THAN CU AND NI

Materials information

Materials Type of material
Chalcopyrite Ore
Pentlandite Ore
Pyrrhotite Ore
Magnetite Gangue
Olivine Gangue
Plagioclase Gangue

Alteration

  • (Local) None Related To The Ore-Forming Process

Analytical data

Result 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
Result ZIENTEK, 1993
Result UNPUB DATA): BASAL SERIES: DISSEMINATED ORE PT=7.15 (140), PD=15 (78), RH=1 (2)
Result 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)
Result NET-TEXTURED ORE PT=4.2 (49), PD=14.5 (130), RH=1 (9)
Result 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).

Mineral occurrence model information

Model code 1
USGS model code 1
Deposit model name Stillwater Ni-Cu

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Ultramafic Intrusive Rock > Peridotite
    Rock unit name Stillwater Complex, Ultramafic Series, Peridotite Zone;Stillwater Complex, Basal Series;Stillwater Complex;
    Rock description Stillwater Complex, Ultramafic Series, Peridotite Zone;Stillwater Complex, Basal Series;Stillwater Complex;

Nearby scientific data

(1) -109.89996, 45.37686
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure 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 of structure Local
Structure description See Deposit Description

Ore body information

  • General form LENTICULAR TO TABULAR CONCENTRATIONS OF SUFLIDE MINERALS

Controls for ore emplacement

  • Imnmiscible Sulfide Liquid Enriched In Ni And Cu Exsolved From Mafic Silicate Magma And Accumulated Near The Lower Contact Of The Stillwater Complex. Assimilation Of Sulfur From Rocks Adjacent To The Stillwatr Complex May Have Led To The Exsolution Of The Sulfide Liquid (Zientek And Ripley, 1990)

Comments on the geologic information

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

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic
Deposit size Small
Significant No
Discovery year 1967

Mining district

District name In Stillwater Complex

Land status

Ownership category Private

Ownership information

  • Type Operator
    Owner Anaconda Co.
    First year 1970

Comments on the production information

  • NO PRODUCTION

Reserves and resources

  • Type In-situ
    Estimate year 1978
    Total resources 65000mt ore
    Commodity Subtype Grade units Group Importance Year
    Nickel Ni 0.31 wt-pct Nickel Major 1978
    Copper Cu 0.29 wt-pct Copper Major 1978
  • Type In-situ
    Estimate year 1987
    Total resources 11000mt ore
    Commodity Subtype Grade units Group Importance Year
    Nickel Ni 0.24 wt-pct Nickel Major 1987
    Copper Cu 0.22 wt-pct Copper Major 1987

Comments on the reserve resource information

  • 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.

Comments on the workings information

  • THERE ARE NO WORKINGS IN THE PART OF THE MOUAT DEPOSIT SOUTH OF VERDIGRIS CREEK

Comments on 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
  • (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.

Reference information

Bibliographic references

General comments

Subject category Comment text
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
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).
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

Reporter information

Type Date Name Affiliation Comment
Reporter 01-SEP-1993 Peterson, Jocelyn A. U.S. Geological Survey
Updater 01-OCT-1993 Zientek, Michael L. U.S. Geological Survey

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Operator history (post-MRDS)

MRDS records operators as of each record's last update (≤ 2019). Some of the operators listed here have since changed hands or dissolved:

  • Anaconda Co. — dissolved ~1977
    Acquired by Atlantic Richfield (ARCO) in 1977 and shut down most operations in the 1980s. Mineral assets were sold off piecemeal; some are now in Glencore via intermediate owners.

Curated by qvyshift.com from publicly-reported M&A activity (SEC filings, press releases, USGS Mineral Yearbooks). Not authoritative — verify against primary sources before relying on it. The MSHA panel above is the current authoritative source for actively-permitted mines.

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