Benbow Mine

Site Name

Primary: Benbow Mine
Secondary: Benbow Chromite Deposit

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Commodity

Primary: Chromium
Tertiary: Iron

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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

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Workings

Not available

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Ownership

Owner Name: Boulder Gold, N. L.
Home Office: Colorado
Info Year: 1988

Owner Name: Bill Mouat Estate
Percent: 100.0
Home Office: Montana
Info Year: 1988

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Underground
Mining Method: Unknown
Year First Production: 1941
Discovery Year: 1918
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

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Unknown: Enstatite
Unknown: Olivine
Unknown: Forsterite
Unknown: Chromite
Unknown: Bronzite

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Comments

Comment (Geology): CR:FE RATIO AVERAGES 1.72:1 CHEMICAL ANALYSIS OF REPRESENTATIVE SAMPLE (USBM RI 6448, 1964).: HEAD MINERAL CR2O3 7.75 42.6 FE 9.72 19.2 SI02 33.4 1.24 CAO .50 .10 MGO 29.5 11.8 AL203 4.88 17.0

Comment (Economic Factors): TRANSPORTATION COSTS- TRUCK HAUL= $2.71/ TONNE RAIL HAUL= $22.428/ TONNE

Comment (Production): FROM 1941 TO 1943, THE ANACONDA CO. HAD MINED FROM BENBOW 203800 MT OF ORE AND MILLED 169170 MT TO PRODUCE 65831 MT OF CONCENTRATE AVERAGING 41.5 PERCENT CR2O3. PRODUCTION WAS HALTED BY GOVERNMENT ORDER AS HIGHER-GRADE, FOREIGN CHROMITE ORES BECAME AVAILABLE.

Comment (Names): PART OF STILLWATER COMPLEX.

Comment (Reserve-Resource): THE MAS RESOURCE MATRIX ONE IS PREDICATED ON BUREAU OF MINES MEASUREMENTS OF ORE BLOCKS DEVELOPED BY THE ANACONDA MINING CO. IN 1941-1943. THE MEASURED AND INDICATED(DEMON- STRATED) ORE CATEGORIES WERE INCREASED TO INCLUDE ALL ORE ABOVE THE PROPOSED NO. 6 LEVEL AT WEST BENBOW AND ABOVE 8,100 FEET (2,469 M) ELEVATION AT EAST BENBOW. ADDITIONAL IDENTIFIED ORE WAS INFERRED TO 7,100 FEET (2,164 M) ELE- VATION, THE LOWEST CHROMITE SURFACE EXPOSURE ON THE MOUAT PROPERTY. A POTENTIAL RESOURCE UNDER CENTRAL BENBOW WAS NOT ESTIMATED, AS A LARGE SHEAR ZONE EXISTS, RESULTING IN MAJOR DILUTION AND GROUND SUPPORT PROBLEMS. THE ORE GRADE WAS DETERMINED BY UNDERGROUND SAMPLING AND VOLUME AVERAGING AND DOES NOT COMPENSATE FOR DILUTION. MINE RUN ORE IS ESTIMATED AT 22.0 PERCENT CR2O3. CR:FE RATIO AVERAGES 1.72:1.

Comment (Geology): OREBODY TYPE- ORIGINAL ROCK FORMING MINERAL. ALTERATION- SERPENTINIZATION IN FAULTED AREAS.

Comment (Deposit): GSC ID # ISM0046 USGS LIST AS OF JUNE 95. MO60101 NOT ON THIS LIST. LAT/LONG ON 06/95 USGS LIST IS N452200/W1094900. ALSO LISTED AS ISMI-CR056 ON USGS LIST, 06/95.

Comment (Workings): MINE ROAD LENGTH - 11 KM ELECTRICAL SOURCE - 14 KM WATER SOURCE - ON SITE ENVIRONMENTAL DISTURBANCE MINIMAL - SURFACE FACILITIES RE- STRICTED TO PREVIOUS MINE SITE, ROADS, ETC.

Comment (Economic Factors): PROPOSED TO START UP IN 1993. FROM 1941-43 COMPANY MINED 203,800 MT ORE, MILLED 169,170 MT ORE AND PRODUCED 65,831 MT CONCENTRATE. AT 41.5 PCT CR2O3; CR:FE RATIO AVERAGES 1.72;1.0.

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References

Reference (Production): BENEFICIATION OF OFF-GRADE CHROMITE AND PRODUCTION OF FER-

Reference (Production): CHEMICAL BENEFICIATION OF CHROMITE ORES. U.S. BUR OF MINES

Reference (Deposit): WIMMLER, N.L. INVESTIGATION OF CHROMITE DEPOSITS OF THE

Reference (Deposit): JACKSON, E.D. THE CHROMITE DEPOSITS OF THE STILLWATER SOM-

Reference (Reserve-Resource): SCHAFER, P.A. CHROMITE DEPOSITS OF MONTANA. MONTANA BUR. OF

Reference (Reserve-Resource): PEOPLES, J.W., AND A.L. HOWLAND. CHROMITE DEPOSITS OF THE

Reference (Production): GRADE CHROMITES FROM THE STILLWATER COMPLEX, MONTANA. U.S.

Reference (Deposit): JONES, W.R., J.W. PEOPLES, AND A.L. HOWLAND. IGNEOUS AND

Reference (Deposit): (GRATON SALES), V. 2, NEW YORK, AIME, 1968, PP. 1495-1510.

Reference (Deposit): MCHUGH, E., 1994, MLA REPORT IN PREPARATION.

Reference (Deposit): MONTANA, U.S. BUR. OF MINES R.I. 4368, 1948, 41 PP.

Reference (Deposit): U.S. GEOLOGICAL SURVEY OPEN FILE RPT., 1954, 2 MAPS, 8 SECTIONS

Reference (Deposit): MOUNTAIN VIEW LAKE AREA, STILLWATER COUNTY, MONTANA,

Reference (Deposit): GEOLOGIC MAP, SECTIONS, AND UNDERGROUND WORKINGS OF THE

Reference (Deposit): 99 PP.

Reference (Deposit): PEOPLES, J.W., A.L. HOWLAND, W.R. JONES, AND D. FLINT.

Reference (Deposit): SOUTHWESTERN MONTANA. U.S. GEOLOGICAL SURVEY CIRC. 68H, 1973,

Reference (Deposit): NORTHERN PART OF THE MT. WOOD AND MT. DOUGLAS QUADRANGLES,

Reference (Deposit): TIAL OF THE STILLWATER COMPLEX AND ADJACENT ROCKS IN THE

Reference (Deposit): PAGE, N.J., AND J.C. DOHRENWEND. MINERAL RESOURCE POTEN-

Reference (Deposit): U.S. GEOLOGICAL SURVEY BULL. 1071-H, 1960, PP. 281-340.

Reference (Deposit): TECTONIC STRUCTURE OF THE STILLWATER COMPLEX, MONTANA.

Reference (Production): NORTHWEST CHROMITE ORES. U.S. BUR OF MINES R.I. 5646, 1960

Reference (Production): R.I. 3817, 1945, 26 PP.

Reference (Production): HUNTER, WILLARD L. AND LLOYD H. BANNING. PYROMETALLURGICAL

Reference (Reserve-Resource): MINES AND GEOL. MEM. 18, 1937, 35 PP.

Reference (Reserve-Resource): MONTANA. U.S. GEOLOGICAL SURVEY BULL. 922-N, 1940, PP. 371-416.

Reference (Reserve-Resource): EASTERN PART OF THE STILLWATER COMPLEX, STILLWATER COUNTY,

Reference (Geology): AMER. SPEC. PAPER 1, 1963, PP. 46-54.

Reference (Geology): MITE COMPOSITION IN THE STILLWATER COMPLEX. MIN. SOC.

Reference (Geology): JACKSON, E.D. STRATIGRAPHIC AND LATERAL VARIATION OF CHRO-

Reference (Geology): U.S. GEOLOGICAL SURVEY PROF. PAPER 358, 1961, 106 PP.

Reference (Geology): THE ULTRAMAFIC ZONE OF THE STILLWATER COMPLEX, MONTANA.

Reference (Geology): JACKSON, E.D. PRIMARY TEXTURES AND MINERAL ASSOCIATIONS IN

Reference (Geology): AMER. MEM. 80, 1966, 230 PP.

Reference (Geology): HESS, H.H. STILLWATER IGNEOUS COMPLEX, MONTANA. GEOL. SOC.

Reference (Production): BUR OF MINES R.I. 6448. 1964, 29 PP.

Reference (Deposit): 1962, 96 PP.

Reference (Deposit): PLEX, MONTANA. IN ORE DEPOSITS IN THE U.S., 1933-1967,

Reference (Deposit): ANONYMOUS. CHROMIUM MATERIALS SURVEY. U.S. DEPT. COMMERCE,

Reference (Production): 14 PP.

Reference (Production): SULLIVAN, G.V. AND G.F. WORKENTINE. BENEFICATING LOW-

Reference (Production): SULLIVAN, G.V. AND W.A. STICKNEY. FLOTATION OF PACIFIC

Reference (Production): ROCHROMIUM. U.S. BUR OF MINES R.I. 6010, 1962, 16 PP.

Reference (Deposit): STILLWATER COMPLEX, STILLWATER AND SWEETGRASS COUNTIES,

Reference (Production): BOERICKE, F.S. AND W.M. BANGERT. EFFECT OF VARIABLES IN

Reference (Geology): GEOLOGICAL SURVEY OPEN FILE RPT., 1954, 3 MAPS, 14 SECTIONS.

Reference (Geology): THE STILLWATER COMPLEX IN STILLWATER COUNTY, MONTANA. U.S.

Reference (Geology): GEOLOGICAL MAPS AND SECTIONS OF THE EASTERN PART OF

Reference (Geology): JACKSON, E.D., A.L. HOWLAND, J.W. PEOPLES, AND W.R. JONES.

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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.