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Grand Island-Caribou District

Past Producer in Boulder county in Colorado, United States with commodities Silver, Lead, Gold, Zinc, Copper, Uranium, Titanium
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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. Economic information about the deposit and operations
  13. Mining district
  14. Bibliographic references
  15. Reporter information

Geologic information

Identification information

Deposit ID 10141356
Record type District
Current site name Grand Island-Caribou District
Alternate or previous names Caribou , Cardinal, Eldora , Nederland , Grand Island

Geographic coordinates

Point of reference Ore Body
Geographic coordinates: -105.57892, 39.9811 (WGS84)
Elevation 2682
Location accuracy 1000(meters)

Site location context

Political divisions (FIPS codes)

Boulder(county)

Colorado(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Nederland(quadrangle 1:24,000 scale)

Denver West(quadrangle 1:100,000 scale)

Denver(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

St. Vrain(hydrologic unit)

South Platte(hydrologic accounting unit)

South Platte(hydrologic subregion)

Missouri(hydrologic region)

Federal lands

Arapaho and Roosevelt National Forests(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Colorado Boulder

Comments on the location information

  • The district is centered on the old town of Caribou, NE/4 sec. 8, T1S, R73W, about 4 miles NW of Nederland; it lies in the northwest quarter of the township. Most mines and veins are in and adjacent to a Tertiary(?) stock just west of Caribou and on Boulder County Hill a mile east. To the east, the district abuts the west end of the Boulder Tungsten district.
  • The district includes mines and deposits at Grand Island, Caribou, and Cardinal, but excludes those at Eldora (a separate district). The district includes the Caribou Consolidated District and Caribou Gold and Silver District of Calais Resources.

Commodities

Commodity Importance
Silver Primary
Lead Primary
Gold Primary
Zinc Critical Secondary
Copper Secondary
Uranium Tertiary
Titanium Critical Tertiary

Comments on the commodity information

  • Silver is the main economic product; lead and gold are of secondary importance. Titanium might be recovered from titaniferous iron deposits at Caribou. Uranium has been found at the Caribou Mine, but production is negligible.
  • Gangue contains carbonate minerals.

Materials information

Materials Type of material
Argentite Ore
Chalcopyrite Ore
Galena Ore
Pyrargyrite Ore
Silver Ore
Sphalerite Ore
Titaniferous Magnetitite Ore
Pitchblende Ore
Cerargyrite Ore
Pyrite Gangue
Quartz Gangue

Alteration

  • (Local) silicified, pyritized, argillized, and chloritized wall rock

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Monzogabbro
    Rock unit name Caribou stock
    Stratigraphic age (youngest) Precambrian
  • Host or associated Associated
    Rock type Metamorphic Rock > Schist
    Rock unit name Idaho Springs Formation
    Stratigraphic age (youngest) Precambrian
  • Host or associated Associated
    Rock type Metamorphic Rock > Gneiss
    Rock unit name Idaho Springs Formation
    Stratigraphic age (youngest) Precambrian
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid
    Rock unit name Boulder Creek Granite
    Stratigraphic age (youngest) Tertiary

Nearby scientific data

Ore Body (1) -105.57892, 39.9811
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description ore shoots localized at vein junctions and by changes in dip or strike

Comments on the geologic information

  • The Grand Island-Caribou district is underlain by igneous and metamorphic rocks of Precambrian age and intrusive rocks of Tertiary(?) (Laramide) age. The dominant structure at Caribou is a NNE-trending anticline that controlled emplacement of the Caribou stock. Veins trending NE and east-west form an interconnecting system that contains the silver-lead ore deposits at Caribou; gold-bearing veins trending NW lie to the east. Three ore deposit types are lead-silver veins, pyritic gold veins, and titaniferous magnetite bodies in the Caribou stock.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Past Producer

Mining district

District name Grand Island-Caribou District

Comments on the production information

  • Total value of production from 1869 to 1924 is estimated at $6 million, mostly silver, plus some lead and gold. In the early days, very rich silver ore was produced from upper levels of the Caribou and other mines on the NE slope of Caribou Hill. There was little activity in the district from 1900 to 1948, when the Caribou mine was reopened and produced about $0.5 million through 1951. Work on a small scale at the Cross mine, from 1977 to 1982, resulted in production valued at $2.1 million.

Comments on the reserve resource information

  • As of 2005, Calais Resources reports a total resource (measured, indicated, and inferred) of: 437,240 oz Au and 12,575,240 oz Ag, contained in 1,058,000 tons of mineralized material for the Caribou/Cross project. The company continued exploration in the district in 2004 and 2005.
  • Sunshine Mining Co. evaluated the Caribou mine, in 1980 and in 1994, and concluded that no more work be done. Extensive files on the Caribou and Cross mines include various reports, assays and maps dated from 1919 to 1994 that may have dated or optimistic resource estimates.

Reference information

Bibliographic references

  • Deposit

    MINE MAP REPO # 409114

  • Deposit

    Vanderwilt, J.W., 1947, Mineral resources of Colorado: State of Colorado Mineral Resources Board, 547 p.

  • Geology

    Lovering, T. S., and Goddard, E. N., 1950, Geology and Ore Deposits of the Front Range, Colorado: U.S. Geological Survey Professional Paper 223, 319 p.

  • Commodity

    Moore, F. B., Cavender, W. S., and Kaiser, E. P., 1957, Geology and uranium deposits of the Caribou area, Boulder County, Colorado: U.S. Geological Survey Bulletin 1030-N, pp. 517-552.

  • Commodity

    Harrer, C.M., and Tesch, W.J., Jr., 1959, Reconnaissance of iron occurrences in Colorado, U.S. Bureau of Mines Information circular 7918, 82 p.

  • Deposit

    Sunshine Mining Co. Colorado exploration files, unpublished data, Colorado Geological Survey.

  • Reserve-Resource

    Calais Resources corporate info., accessed from internet on 12/20/2005.

  • Names

    Dunn, L.G, 2003, Colorado mining districts: A reference: Golden, Colo., Colorado School of Mines Library, 364 p.

  • Deposit

    Smith, D. A., 2003, Silver saga, the story of Caribou, Colorado (rev. ed.): Boulder, University Press of Colorado, 230 p.

Reporter information

Type Date Name Affiliation Comment
Reporter 16-DEC-05 Beach, Richard A. Colorado Geological Survey

Beyond USGS

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

Maps centered on this site

Authoritative Colorado resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.