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Mount Brock

Occurrence in Alaska, United States with commodities Silver, Copper, Lead, Zinc, Gold, Antimony
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Geologic information

Identification information

Deposit ID 10002219
MRDS ID A013120
Record type Site
Current site name Mount Brock
Alternate or previous names Mount Brack
Related records 10282822

Geographic coordinates

Geographic coordinates: -136.28211, 59.10973 (WGS84)
Relative position This occurrence is in Glacier Bay National Park and Preserve about 0.8 miles northwest of the summit of Mount Brock; it is on a ridgetop at an elevation of approximately 3,900 feet. It corresponds to location 6 of Cobb (1972 [MF424]). A more detailed location is shown in Figure C-67 of Brew and others (1978). Note: Mount Brock is shown on some maps as Mount Brack. Schorr (1991) asserts that the correct name is Mount Brock, named for Canadian geologist R.W. Brock who visited Muir Inlet in 1913.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Copper Primary
Lead Primary
Zinc Primary
Gold Secondary
Antimony Secondary

Materials information

Materials Type of material
Arsenopyrite Ore
Chalcopyrite Ore
Galena Ore
Pyrite Ore
Sphalerite Ore
Ankerite Gangue
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Alteration is mentioned but not described.

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 Sedimentary Rock > Clastic Sedimentary Rock > Siltstone

Nearby scientific data

(1) -136.28211, 59.10973
ListMap

Comments on the geologic information

  • Geologic Description = The following description is summarized from Brew and others (1978).?The prospect consists of hydrothermal quartz-calcite veins 0.1- to 1.8-foot thick that contain chalcopyrite, sphalerite, galena, pyrite, arsenopyrite, and ankerite in Devonian and Permian andesite, graywacke, limestone, hornfels, and siltstone. The veins strike north and dip to the east. Altered zones (presumably altered zones around or between the veins) are sparsely mineralized. The veins contain up to 1.3% copper, 0.9% lead, 4.2% zinc, 0.7% antimony, 70 ppm silver, and traces of gold. The mineralization must be younger than the Permian age of some of the host rocks and is probably the same age as nearby Cretaceous intrusive rocks.
  • Age = No older than Permian based on age of host rocks and probably Cretaceous, based on the age of nearby intrusive rocks (Brew and others, 1978).

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau (Glacier Bay subdistrict)

Comments on the reserve resource information

  • Reserves = According to Brew and others (1978), the individual veins are neither rich enough nor extensive enough to be economic and the veins are not close enough together to be mined as a unit.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013120
USGS Alaska Resource Data File ARDF SK014

Bibliographic references

  • Deposit

    MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Skagway quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-424, 1 sheet, scale 1:250,000.

  • Deposit

    Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

  • Deposit

    Cobb, E.H., 1981, Summaries of data and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska, Supplement to Open-File Report 78-316, Part A in Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-A, 11 p.

  • Deposit

    Berg, H.C., 1984, Regional geologic summary, metallogenesis, and mineral resources of southeastern Alaska: U.S. Geological Survey Open-file Report 84-572, 298 p., 1 plate, scale approx. 1:600,000.

  • Deposit

    Schorr, A.E., 1991, Alaska Place Names, 4th edition: Anchorage, Alaska, The Denali Press, 191 p.

  • Deposit

    Still, J.C., 1991, Bureau of Mines mineral investigations in the Juneau mining district, Alaska, 1984 - 1988, v. 2, Detailed mine, prospect, and mineral occurrence descriptions, section B, Glacier Bay subarea: U.S. Bureau of Mines of Mines Special Publication, 69 p.

  • Deposit

    Cobb, E.H., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Skagway quadrangle, Alaska; Supplement to Open-File Report 78-316; Part A, Summaries of data to January 1, 1980: U.S. Geological Survey Open-File Report 81-82-A, 11 p.

  • Deposit

    MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1967, Mineral resources of Glacier Bay National Monument, Alaska: U. S. Geological Survey Open-File Report 151, 176 p.

Comments on the references

  • Primary Reference = Brew and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins (Cox and Singer, 1986; model 22c).
Deposit Other Comments = the deposit is within Glacier Bay National Park and Preserve where exploration and development is restricted.

Reporter information

Type Date Name Affiliation Comment
Reporter 04-FEB-2001 T.C. Crafford T. Crafford & Associates