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Mount Coxcomb

Prospect in Alaska, United States with commodities Gold, Silver
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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. Nearby scientific data
  10. Economic information about the deposit and operations
  11. Mining district
  12. Links to other databases
  13. Bibliographic references
  14. General comments
  15. Reporter information

Geologic information

Identification information

Deposit ID 10003260
MRDS ID A106000
Record type Site
Current site name Mount Coxcomb

Geographic coordinates

Geographic coordinates: -166.4785, 53.88383 (WGS84)
Relative position Mineralized area on the northwest side of Mount Coxcomb extends for approximately 2 km along coast of Iliuliuk Bay, immediately southwest of Summer Bay and extends into Summer Bay on its west side. Equivalent to anomaly no. 17 of Christie (1974).

Site location context

Political divisions (FIPS codes)

Aleutians West(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Unalaska C-2(quadrangle 1:63,360 scale)

Unalaska NE(quadrangle 1:100,000 scale)

Unalaska SE(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Fox Islands(hydrologic unit)

Aleutian Islands(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Federal lands

Ounalashka Corporation(ANCSA Village)

ANCSA Village NTVPIC(Type of land area)

NTVPIC(Federal land areas administered by NTVPIC)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Gold Primary
Silver Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Chlorite Gangue
Quartz Gangue
Sericite Gangue

Alteration

  • (Local) Regional propylitic alteration overprinted by silicic and sericitic alteration is common, as is the introduction of pyrite throughout the altered volcanic breccia. Area is highly iron-stained, apparently derived from weathering of pyrite.

Mineral occurrence model information

Model code 105
USGS model code 25a-d
Deposit model name Epithermal vein, generic
Mark3 model number 119

Nearby scientific data

(1) -166.4785, 53.88383
ListMap

Economic information

Comments on the geologic information

  • Geologic Description = Alteration and mineralization occurs in rocks of the Unalaska Formation (see Drewes and others, 1961), composed of volcanic breccia, volcaniclastic sedimentary rocks, debris flows, and rare lava flows. The dominant lithology within the altered zone appears is regionally propylitized andesitic tuff and flows (Randolph, 1991). A number of hypabyssal dioritic stocks, possibly cupolas related to emplacement of the Captain's Bay pluton, intrude the prospect areas. Emplacement of the stocks generated hydrothermal systems, which filled structures and fractures with cockscomb quartz, presumably related to stock emplacement (Randolph, 1991). Randolph (1991) reports two styles of mineralization at Mt. Coxcomb. Most common is a wide-spaced quartz vein system characterized by scattered emplacement of non-brecciated comb quartz over a large area. Veins fill open space fractures, 3 inches to 3 feet (0.7 to 1 m) wide, 10 to 20 feet (3 to 6 m) long, spaced a few to tens of feet apart. Veining is spacially related to hypabyssal stocks and faulting. Ore grade gold is restrict to the quartz veining. The veins occassionally yield pyrite or arsenopyrite, but have low silver, mercury, and base metal values. The second style of mineralization is in large-scale vein systems that are composite emplacement of brecciated cockscomb quartz along major structural breaks. The structures are typically 10 to 40 feet (3 to 12 m) thick and more than 1,000 feet (300 m) long. These display no wall rock alteration, except for silicification within the anastomosing zones. Gold values can reach or grade, silver, mecury and arsenic are only weakly anomalous and the veins are sulfide-free.
  • Age = Late Tertiary or younger

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Aleutians

Comments on the workings information

  • Workings / Exploration = Battle Mountain Exploration Co. (BMEC) established three sampling grids over part of area. The C1 and C3 grids were located on wide-spaced vein systems as described above although a zone of the large-scale vein system also crosses the C1 grid. The C1 grid produced gold values to 776 ppb and first-pass gold-in-rock values of 0.36 oz/t (12 ppm) and greater than 50 ppm arsenic; mineralization appeared to be restricted to wide-spaced cockscomb quartz veins and not to pervasively silicified or 'crackle-brecciated' tuffs. A geophysical survey of the grid indicated a major north dipping mineralizing structure, localized on a mapped fault, runs through the grid. Channel sampling along the trend outlined at least 322 feet (100 m) of 0.06 oz/t gold. The C2 grid produced no significant gold values. The C3 grid, located approximately 1 km north of the C1 grid, yielded significantly higher gold-in-soil than C1 at 3,500 ppb and significantly lower arsenic than the C1 grid. Sampling of quartz veins produced gold and silver values as high as 2.932 oz/t (102 ppm) and 14.3 ppm. A geophysical survey outlined a NNW-trending anomaly within the north central portion of the grid. Rock sampling along this anomaly averaged 0.75 oz/t (26 ppm) gold and defined an open-ended trend measurely roughly 100 by 200 feet (30 by 60 m). BMEC reported that gold had been panned in the vicinity of Mt. Coxcomb since before 1900 and BMEC mapping crews found several prospect pits and tunnels in the area.

Reference information

Bibliographic references

  • Deposit

    Drewes, Harold, Fraser, G.D., Snyder, G.L., and Barnett, H.F., Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-S, p. 583-676.

  • Deposit

    Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)

  • Deposit

    Randolph, D.B., 1991, Unalaska project, 1990 final report: Battle Mountain Exploration Company, Alaska District, 62 p., 5 appendices, 15 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)

  • Deposit

    F.H. Wilson and E.A. Bailey, unpublished data, 1992.

Comments on the references

  • Primary Reference = Randolph, 1991

General comments

Subject category Comment text
Deposit Model Name = Epithermal gold vein; disseminated gold
Deposit Other Comments = At north end of altered zone, along Summer Bay road, the ruins of what may have been a tramway come down a steep gully. During WWII, Mount Coxcomb was the site of a major shore battery and the tramway may be related to that installation rather than any workings.

Reporter information

Type Date Name Affiliation Comment
Reporter 06-MAY-1996 F.H. Wilson U.S. Geological Survey

Beyond USGS

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

Maps centered on this site

Authoritative Alaska resources

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