Boulder Creek Molybdenum Deposit

Site Name

Primary: Boulder Creek Molybdenum Deposit
Secondary: Little Boulder Creek
Secondary: Little Boulder Creek Moly Deposit
Secondary: Baker Lake Moly Deposit
Secondary: Fuller and Baker
Secondary: Boulder Creek
Secondary: Baker Lake

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Commodity

Primary: Molybdenum
Tertiary: Tungsten
Tertiary: Zinc
Tertiary: Gold
Tertiary: Lead

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Location

State: Idaho
County: Custer
District: Little Boulder

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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.
Administrative Organization: Challis National Forest

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Holdings

Type: Located Claim

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Workings

Type: Surface

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Ownership

Owner Name: Grupo Mexico
Percent: 100.0
Home Office: Avenida Baja California 200 Col. Roma Sur Mexico D.F. MEX 06760 Mexico
Years: 1999 -

Owner Name: Asarco (American Smelting And Refining Co.)
Percent: 100.0
Home Office: New York
Info Year: 1982

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Surface
Mining Method: Unknown
Milling Method: Flotation
Discovery Year: 1922
Years of Production:
Organization:
Significant: Y
Deposit Size: S

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Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern 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

Name: Skarn (Tactite)
Role: Host
Age Type: Host Rock
Age Young: Eocene

Name: Limestone
Role: Host
Age Type: Host Rock
Age Young: Pennsylvanian

Role: Host
Age Type: Host Rock Unit
Age Young: Pennsylvanian

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Analytical Data

Not available

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Materials

Ore: Sphalerite
Ore: Molybdenite
Ore: Galena
Gangue: Calcite
Gangue: Feldspar
Unknown: Quartz
Unknown: Scheelite
Unknown: Arsenopyrite
Unknown: Biotite
Unknown: Chlorite
Unknown: Tremolite
Unknown: Epidote
Unknown: Garnet
Unknown: Hornblende
Unknown: Pyrite
Unknown: Diopside

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Comments

Comment (Geology): MOLYBDENITE IS THE SOLE ORE MINERAL. SCHEELITE IS FOUND THROUGHOUT THE DEPOSIT(.007 WO3), BUT IN AMOUNTS TOO SMALL TO RECOVER. A HIGHER GRADE SCHEELITE AREA (GRADE UNKNOWN) IS PRESENT IN THE BANDED TACTITE ZONE ON THE NE EDGE OF THE PROPOSED PIT. THIS MAY BE OF HIGH ENOUGH GRADE TO BE RECOVERABLE, BUT NOT ENOUGH INFORMATION IS KNOWN ABOUT IT AS YET.

Comment (Reserve-Resource): CAVANAUGH HAS 149000000 MT IN NORTH ORE ZONE AT .15% MOS2 AND 18000000 IN SOUTH ORE ZONE AT .15% MOS2. TSCHANZ HAS 91000000 MT IN NORTH ORE ZONE AT .16% MOS2. AND 32000000 MT IN SOUTH ORE ZONE AT .12% MOS2.

Comment (Reserve-Resource): BECAUSE OF CONFLICTING TONNAGE FIGURES AND LACK OF INFORMATION ON HOW THE FIGURES WERE CALCULATED, NEW ONES WERE CALCULATED. FOR A COMPLETE DESCRIPTION OF HOW RESOURCE DATA WAS DERIVED SEE APPENDIX B-2 OF REPORT. MATRIX ONE (NORTH ORE ZONE) DEALS WITH ROCK GREATER THAN .15% MOS2 (.165% ON THE AVERAGE). 90% ROCK IS EXPOSED IN OUTCROP, OR IN DRILL HOLE, PROJECTED TO A DEPTH OF 7700 FEET THE BOTTOM ELEVATION OF DEEPEST DRILL HOLE. THE OTHER PROBABILITY LEVELS (75-25%) ARE BASED ON DEEPER PROJECTIONS OF THE ORE, AND ON PROJECTIONS OF THE EXPOSED ORE TO THE NORTH AND SOUTH(AREAS COVERED BY VOLCANICS AND TALUS.) MATRIX 2 (NORTH ORE ZONE) DEALS WITH ROCK GREATER THAN .05% MOS2 (.10% ON THE AVERAGE). THIS IS ROCK THAT MUST BE REMOVED IN ORDER TO EXTRACT THE 90% PROB ORE OF MATRIX 1. MATRIX 3 (SOUTH ORE ZONE) DEALS WITH ROCK GREATER THAN .15% (.165% ON THE AVERAGE). MATRIX 4 (NORTH ORE ZONE) IS THE TONNAGE PROPOSED FOR MINING IT IS MATRIX ONE 90% PROB ORE, PLUS THE MINERALIZED ROCK THAT MUST BE REMOVED IN ORDER TO EXTRACT THE 90% PROB. ORE. THE MINERALIZED ROCK THAT MUST BE REMOVED IS COMPOSED OF MATRIX 2 LOW GRADE ROCK AND SOME OF MATRIX ONE 75% PROB ROCK (19000000 MT)

Comment (Ownership): PROPERTY CONSISTS OF 51 UNPATENTED CLAIMS IN THE SAWTOOTH NATIONAL RECREATION AREA.

Comment (Geology): THE BOULDER CREEK DEPOSIT IS A STOCKWORK MOLY DEPOSIT. THE WOOD RIVER SEDIMENTS WERE FRACTURED BY A ANCESTRAL LITTLE BOULDER FAULT ZONE, CREATING A ZONE OF WEAKNESS WHEREBY THE WHITE CLOUD STOCK WAS INTRUDED. THE SEDIMENTS WERE METAMORPHOSED AND ALTEREDY BY FLUIDS FROM THE STOCK. IN MORE INTENSLEY FRACTURED ZONES(NORTH AND SOUTH ORE ZONES) THE FRACTURES WERE HEALED BY MOLY RICH QUARTZ VEINLETS. SUBSEQUENT MOVEMENT ON THE LITTLE BOULDER FAULT (AND OTHER FAULTS) HAS PRODUCED THE PRESENT ORE BODY SHAPE. MOST OF THE MINERALIZATION IS CONFINED TO A DIOPSIDE RICH TACTITE (ZONE NEAREST TO INTRUSIVE). MOST OF THE MOLY(95%) IS FOUND IN QUARTZ RICH VEINLETS. MINOR AMOUNTS OF MOLY ARE DISSEMINATED THROUGHOUT THE ROCK. THE GRADE OF MINERALIZATION IS VERY UNIFORM ON THE SURFACE AND AT DEPTH. GRADE GRADUALLY DROPS OFF AS THE DISTANCE FROM THE INTRUSIVE INCREASES.

Comment (Production): ASARCO FROM 1968-1972 CONDUCTED AN INTENSIVE EXPLORATION PROGRAM ON THE PROPERTY. BUT ENVIRONMENTAL OBJECTIONS HAVE PREVENTED ANY FUTHER MAJOR EXPLORATION WORK. ONLY ASSESSMENT WORK HAS BEEN DONE ON THE CLAIMS SINCE 1972.

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References

Reference (Deposit): CAVANAUGH, PAT, 1979, THE GEOLOGY OF THE LITTLE BOULDER CREEK MOLYBDENUM DEPOSIT, CUSTER COUNTY, IDAHO, M.S. THESIS, UNIV. OF MONTANA.

Reference (Deposit): DWYER, CHARLES, 1970, A PRELIMINARY STUDY OF AERIAL TRAMWAY ACCESS AND TRANSPORT FOR A PROPOSED MINING OPERATION IN THE CHALLIS NATIONAL FOREST, A USFS REPORT.

Reference (Deposit): BENNETT, E.H., 1973, PETROLOGY AND TRACE ELEMENT DISTRIBUTION OF THE WHITE CLOUD STOCK: PHD THESIS, UNIV. OF IDAHO, 172 P.

Reference (Deposit): BLM, BOISE, IDAHO, 1981, MASTER TITLE PLATS.

Reference (Deposit): USBM, MINERAL PROPERTY FILE, WFOC, 0160370455.

Reference (Deposit): VISGER, FRANK, 1974, THE GEOLOGY OF THE UNCLE JESS MOLYBDENITE DEPOSIT, CUSTER CO., IDAHO, M.S. THESIS, EASTERN WASHINGTON STATE COLLEGE.

Reference (Deposit): THE MINING RECORD, 1981, 'ASARCO WILL NOT SUBMIT OPERATING PLAN', NOVEMBER 1981.

Reference (Deposit): TSCHANZ, C.M., 1986, MINERAL RESOURCES OF THE EASTERN PART OF THE SAWTOOTH N.R.A., CUSTER AND BLAINE COS., IDAHO: U.S. GEOLOGICAL SURVEY BULLETIN 1545-E, P. 243.

Reference (Deposit): SAVAGE, C.N., 1970, EVALUATION OF MINERALS AND MINERAL POTENTIAL OF THE SALMON RIVER DRAINAGE BASIN IN IDAHO: ID. BUREAU OF MINES AND GEOLOGY PAMPHLET 147, 64 P.

Reference (Deposit): THE MINING RECORD, 1981,'AMERICAN MINE CLAIMS STATUS IS UNCHANGED', AUGUST 1981.

Reference (Deposit): PAY DIRT, 1981,'ASARCOS RENEWED INTEREST IN IDAHO MOLY REKINDLES OPPOSITION', AUGUST 1981.

Reference (Deposit): ROSS, C.P., 1937, GEOLOGY AND ORE DEPOSITS OF THE BAYHORSE REGION, CUSTER CO, IDAHO: USGS BULL. 877, 161 P.

Reference (Deposit): MOTZER, WILLIAM, 1978, VOLCANIC STRATIGRAPHY OF AN AREA EAST OF THE WHITE CLOUD PEAKS, SAWTOOTH NRA, CUSTER CO., IDAHO, M.S. THESIS, UNIV OF IDAHO.

Reference (Deposit): MINARIK, ROD, 1982, CLIMAX CORP., PERSONAL COMMUN.

Reference (Deposit): MARVIN, R.F., 1973, LATE CRETACEOUS AGE FOR MOLYBDENITE MINERALIZATION IN CUSTER CO., IDAHO:ISOCHRON/WEST, NO. 7 P.1

Reference (Deposit): KIRKEMO, J., 1965, INVESTIGATIONS OF MOLYBDENUM DEPOSITS IN THE CONTERMINOUS U.S., 1942-1960:USGS BULL. 1182-E P. E54-55.

Reference (Deposit): ANDERSON, 1952, MULTIPLE EMPLACEMENT OF THE IDAHO BATHOLITH, JOUR. OF GEOLOGY, V. 60, P 255-265.

Reference (Deposit): ARMSTRONG, 1978, K-AR DATES FOR MINERALIZATION IN THE WHITE CLOUD-CANNIVAN PORPHYRY MOLYBDENUM BELT OF IDAHO AND MONTANA: ECON. GEOL., V. 73, NO. 1 P 94-108

Reference (Reserve-Resource): TSCHANZ, C.M., 1974, MINERAL RESOURCES OF THE EASTERN PART

Reference (Reserve-Resource): U.S.G.S. OPEN FILE REPORT, 648 P.

Reference (Deposit): BENNETT, E.H., 1981, IDAHO BUREAU OF MINES AND GEOLOGY, PERSONAL COMMUN.

Reference (Deposit): SHAFFER, LYSLE, 1943, BOULDER CREEK MOLYBDENUM DEPOSIT, USBM WAR MINERALS REPORT, UNPUBLISHED.

Reference (Deposit): BARNES, F.D., 1971, A SUMMARY OF GEOLOGY, KNOWN MINERAL RESOURCES, AND MINING HISTROY OF THE WHITE CLOUD MTS., ID., U.S. BLM REPORT.

Reference (Deposit): BALLA, J.C., 1981, PERSONAL COMMUN., ASARCO INC.

Reference (Deposit): BALLA, J.C., 1980, GEOLOGY OF THE LITTLE BOULDER CREEK DEPOSIT, CUSTER COUNTY, IDAHO(ABS.) PROCEEDINGS OF THE SYMPOSIUM ON MINERAL DEPOSITS OF THE PACIFIC N.W., U.S.G.S. OPEN FILE REPORT, 81-355.

Reference (Deposit): CLARK, K.F., 1972, STOCKWORK MOLYBDENUM DEPOSITS IN THE WESTERN CORDILLERA OF NORTH AMERICA: ECON. GEOL., VOL 67, NO. 6, P. 731-758.

Reference (Deposit): KING, R.U., 1964, IDAHO BUREAU OF MINES AND GEOLOGY SPECIAL REPORT NO. 1, P 137.

Reference (Deposit): JONES, JEFF, 1981, SAWTOOTH NRA, PERSONAL COMMUN.

Reference (Deposit): KESTON, NORMAN, 1970, 'THE WHITE CLOUDS ISSUE', WESTERN MINING NEWS.

Reference (Deposit): KING, R.U., 1970, MOLYBDENUM IN THE U.S.: USGS MINERAL INV. RESOURCES MAP MR-55, 21P.

Reference (Deposit): U.S.B.M., MINE MAP FILE, SEQ NO. 0160370455, W.F.O.C.

Reference (Deposit): HAYDEN, TERRY, 1981, PERSONAL COMMUN., PLACER AMAX INC.

Reference (Deposit): CAVANAUGH, PAT, 1982, PERSONAL COMMUNICATION

Reference (Deposit): GREEN, W.R.,1972, DELINEATION OF MINERAL BELTS OF NORTHERN AND CENTRAL IDAHO: IDAHO BUR. OF MINES AND GEOLOGY INFO. CIRCULAR 22, 8P.

Reference (Deposit): CREASEY,S.C., 1944, PRELIMINARY REPORT ON THE BOULDER CREEK (BRONTON) MOLYBDENUM DEPOSIT, CUSTER COUNTY, IDAHO, U.S.G.S. WAR MINERALS REPORT (UNPUBLISHED).

Reference (Deposit): 1975 COMPILE USBM, MINING ACTIVITY LIST, 1974

Reference (Deposit): USBM, 1975, ACTIVITY OF IDAHO MINING PROPERTIES, 1974: USBM; BOISE, IDAHO, 61 P.

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Idaho Gold

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