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  7. Deposit #USGS10192485

Little Boulder Creek Deposit

Clayton, Idaho

44.0553°N 114.5575°W

Mine Overview

The Little Boulder Creek Deposit is near Clayton, Idaho. Historically the site has been associated with the Boulder Creek Mining District which is now part of the Challis National Forest. The site was first discovered in 1922. The Little Boulder Creek Deposit is a surface mining operation. Mine operations consist of surface workings extending 108.00 hectares (266.87 acres). There is one known shaft. The mining method is open pit. Mine capacity in 1982 was 22680 mt ore/day with a production unit cost of 2.83 $/mt ore. The ore mined is composed of molybdenite, galena and sphalerite with waste material consisting primarily of calcite and feldspar. The ore body is described as tabular shaped 1,250 meters (4,101 feet) long, 200 meters (656 feet) wide, and 300 meters (984 feet) thick. Associated rock in this area is andesite. The Northern Rocky Mountains physiographic province of the Rocky Mountain System characterize the geomorphology of the surrounding area.

Site identification and general characteristics. Learn about USGS mines.

  • Molybdenum Primary Commodity
  • Gold, Lead, and Tungsten Secondary Commodity
  • Site Record Type?
  • Prospect Development Status?
  • Surface Operation Type?
  • Flotation Milling Method?
  • 1922 Year Discovered?
  • Significant Significance?
  • Metallic Site Commodity Type?
  • Small Mine Size?

Mine Names

  1. Name? Status?
  2. Little Boulder Creek Current
  3. Little Boulder Creek Deposit Current
  4. Boulder Creek Molybdenum Deposit Previous
  5. Baker Lake Molybdenum Deposit Previous
  6. Fuller & Baker Previous
  7. Boulder Creek Previous
  8. Baker Lake Previous

Owner Name and Address

Asarco Incorporated

New York
Type
Owner
Stake
Majority

Grupo Mexico

Type
Owner
Stake
Majority

Commodities

Additional textual information about a site or mine.

  1. Commodity Type Importance
  2. Molybdenum Metallic Primary
  3. Gold Metallic Tertiary
  4. Lead Metallic Tertiary
  5. Tungsten Metallic Tertiary
  6. Zinc Metallic Tertiary

Location Info

  1. Continent Country State County
  2. North America The United States Idaho Custer

Meridian / Township / Range Description

  1. Meridian? Township? Section? Aliquot?
  2. Boise Meridian T.8N R.16E Sec. 3 NE

Land Status

Land status information.

  1. Land Status? Admin Area?
  2. National Forest Challis National Forest

Mining Districts

Formal or informal mining district names.

  1. District
  2. Boulder Creek Mining District

Workings

Workings at the site.

Surface Workings #1

  • Type: Surface
  • Surface Area: 108 Hectares
  • Mining Method: Open Pit
  • Status of Mining Method: Proposed
  • Percent Waste Rock: 55.7
  • Average Overburden Thickness: 2
  • Average Bench Height: 15 meters
  • Max Pit Slope: 45 degrees
  • Capacity: 22680 mt ore/day
  • Production Unit Cost: 2.83 $/mt ore
  • Preprod Stripping Volume: 926.119
  • Operating Days Per Year: 350
  • Operating Shifts Per Day: 3
  • Year of Information: 1982
  • Hardness of Ore: Hard Rocks
  • Primary Material Cover: Sand And Gravel

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.

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.

Materials

Minerals or other materials present in the mine.

  1. Role? Material?
  2. Gangue/Waste Calcite
  3. Gangue/Waste Feldspar
  4. Ore Galena
  5. Ore Molybdenite
  6. Ore Sphalerite
  7. Unknown Arsenopyrite
  8. Unknown Biotite
  9. Unknown Chlorite
  10. Unknown Diopside
  11. Unknown Epidote
  12. Unknown Garnet
  13. Unknown Hornblende
  14. Unknown Pyrite
  15. Unknown Quartz
  16. Unknown Scheelite
  17. Unknown Tremolite

Orebody

Characteristics of the ore body.

  • Length:
  • Width: 325.00 meters (1,066.27 feet)
  • Top Depth: 2.00 meters (6.56 feet)
  • Thickness: 400.00 meters (1,312.34 feet)
  • Strike: north 20 west
  • Dip: 80 east
  • Type of Wallrock: silicification, propylitic, carbonate silicate
  • Wallrock Alteration: slight
  • Ore Control: faulting, igneous
  • Unconsolidated Material Thickness: 2 meters average
  • Ore Record Modified: 1983-03-16

  • Length:
  • Width: 200.00 meters (656.17 feet)
  • Top Depth: 2.00 meters (6.56 feet)
  • Thickness: 300.00 meters (984.25 feet)
  • Strike: north 20 west
  • Dip: 80 east
  • Type of Wallrock: silicification, propylitic, carbonate silicate
  • Wallrock Alteration: slight
  • Ore Control: faulting, igneous
  • Unconsolidated Material Thickness: 2 meters average
  • Ore Record Modified: 1983-03-16

  • Length:
  • Width: 150.00 meters (492.13 feet)
  • Top Depth: 2.00 meters (6.56 feet)
  • Thickness: 1,000.00 meters (3,280.84 feet)
  • Strike: north 20 west
  • Dip: 80 east
  • Type of Wallrock: silicification, propylitic, carbonate silicate
  • Wallrock Alteration: slight
  • Ore Control: faulting, igneous
  • Unconsolidated Material Thickness: 2 meters average
  • Ore Record Modified: 1983-03-16

  • Length:
  • Width: 125.00 meters (410.11 feet)
  • Top Depth: 2.00 meters (6.56 feet)
  • Thickness: 175.00 meters (574.15 feet)
  • Strike: north 20 west
  • Dip: 80 east
  • Type of Wallrock: silicification, propylitic, carbonate silicate
  • Wallrock Alteration: slight
  • Ore Control: faulting, igneous
  • Unconsolidated Material Thickness: 2 meters average
  • Ore Record Modified: 1983-03-16

  • Area: 700.00 hectares (1,729.74 acres)
  • Ore Record Modified: 1991-04-18

Rocks

Geological materials at the site.

  1. Class? 1st Order Name? 2nd Order Name? 3rd Order Name? 4th Order Name? Most Specific Name? Begin Time End Time Description?
  2. Associated Rock Volcanic Rock (Aphanitic) Intermediate Volcanic Rock Andesite - Andesite - - -
  3. Host Rock Metamorphic Rock Metasedimentary Rock Quartzite - Quartzite - - -
  4. Host Rock Metamorphic Rock Skarn (Tactite) - - Skarn (Tactite) Eocene Eocene -
  5. Host Rock Sedimentary Rock Carbonate Limestone - Limestone Carboniferous Carboniferous -
  6. Host Rock Wood River Formation - - - Wood River Formation Carboniferous Carboniferous -
  7. Mineralization - - - - - Eocene Eocene -

Physiography

Physiographic area where the resource is found.

  1. Division Province? Section
  2. Rocky Mountain System Northern Rocky Mountains -

Holdings

Mineral rights ownership information.

Notes

PROPERTY CONSISTS OF 51 UNPATENTED CLAIMS IN THE SAWTOOTH NATIONAL RECREATION AREA.

  1. Type?
  2. Located Claim

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.

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).

Nearby Deposits

Other deposits in the same region.

  1. Boulder Creek Deposit

    • Molybdenum commodity Site type Occurrence status
    • Custer, Idaho
    • 0.30 miles
    Read More

  2. Baker Lake Prospect

    • Molybdenum commodity Site type Prospect status
    • Custer, Idaho
    • 0.31 miles
    Read More

  3. Boulder Creek Copper Occurrence

    • Copper commodity Site type Occurrence status
    • Custer, Idaho
    • 0.34 miles
    Read More

  4. Kirtley Lead Prospect

    • Lead commodity Site type Occurrence status
    • Custer, Idaho
    • Vein
    • 1.15 miles
    Read More

  5. Boulder Chain Lakes Prospect

    • Gold commodity Site type Occurrence status
    • Custer, Idaho
    • 1.46 miles
    Read More

  6. Asarco Molybdenum Prospect

    • Molybdenum commodity Site type Prospect status
    • Custer, Idaho
    • Surface
    • 3.62 miles
    Read More

  7. Mcclure Claim

    • Tungsten commodity Site type Occurrence status
    • Custer, Idaho
    • 3.87 miles
    Read More

  8. Gold Leaf Prospect

    • Silver commodity Site type Prospect status
    • Custer, Idaho
    • Vein
    • Surface And Underground
    • 4.10 miles
    Read More

  9. Fissure Borne Mine

    • Gold commodity Site type Mine status
    • Custer, Idaho
    • Vein
    • Underground
    • 4.32 miles
    Read More

  10. Scheelite Tungsten Occurrence

    • Tungsten commodity Site type Occurrence status
    • Custer, Idaho
    • 4.47 miles
    Read More

Nearby Places

Nearby Mining Districts

Nearby Lands

Footnotes

* Mine bounds on map indicate the general area that a mine occupies. For an detailed map, refer to the overseeing BLM field office.

** The mine central point is based on an average of the mine's bounding box(es) and does not necessarily fall on the claim itself.

1 World-class significance is determined by total endowment of the contained commodity. This includes all past production and remaining reserves. Each commodity is considered separately and commodities cannot be combined to arrive at a significant size. The tonnage thresholds are from the mine model grade-tonnage studies. As of June 2008, many entries were classified as significant under less strict rules.

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