Bearskin Gulch

The Bearskin Gulch is a molybdenum, copper, gold, and silver mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Bearskin Gulch

Commodity

Primary: Molybdenum
Primary: Copper
Primary: Gold
Primary: Silver

Location

State: Alaska
District: Alaska Peninsula

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Occurrence
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Porphyry Cu-Mo
Model Name: Porphyry Cu-Au
Model Name: Porphyry Cu

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Secondary biotite is present within the copper-bearing areas and beyond. Chlorite is present throughout the area in all rock types. Sericite is present as veinlet selvages and within the higher sulfide areas on the periphery of the system. Other periphery alteration minerals include epidote, kaolinite, montmorillonite, and pyrophyllite.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Chalcopyrite
Ore: Gold
Ore: Molybdenite
Ore: Pyrite

Comments

Comment (Exploration): Status = Inactive

Comment (Geology): Age = Tertiary

Comment (Reference): Primary Reference = Fields, 1977

Comment (Workings): Workings / Exploration = Bear Creek mapped and sampled this site during the period 1975 to 1976 (Fields,1977). Maximum metal values obtained were 1500 ppm copper, 30 ppm molybdenum, and small amounts of precious metals.

Comment (Deposit): Model Number = 17, 20c, 21a

Comment (Deposit): Other Comments = This site is on lands selected by the Bristol Bay Native Corporation.

Comment (Geology): Geologic Description = The Jurassic Naknek Formation is the main rock unit exposed at the site (Detterman and others, 1981). It consists of graywacke, siliceous siltstone, hornfels, quartzite, and minor grit. The strata strike N 20 to 45 E, and dip 28 to 40 southeast. A small (1000 feet diameter) weakly-mineralized diorite porphyry stock crops out within the western fork of Bearskin Creek.? the sulfide system as exposed is approximately 2 by 4 miles (Fields, 1977). Pyrite and chalcopyrite occur in highly shattered and fractured rocks throughout the area as fracture fillings, veinlets, and disseminations. Some of the better copper mineralization appears to occur within the sandstone and grit units of the Naknek Formation. The sulfide content of the sedimentary rocks varies from 3 to 10 percent with a high pyrite to chalcopyrite ratio. Within the diorite sulfide content is 1 to 2 percent.? Secondary biotite is present within the copper-bearing areas and beyond. Chlorite is ubiquituous throughout the area in all rock types. Sericite occurs as veinlet selvages and within the higher sulfide areas on the periphery of the system. Other peripheral alteration minerals include epidote, kaolinite, montmorillonite, and pyrophyllite.? In the eastern fork of Bearskin Creek metal values ranged from 235 to 1500 ppm copper, 0.01 to 0.13 ppm gold, 4 to 30 ppm molybdenum, 0 to 4.1 ppm silver (Fields, 1977). These values outlined an area of 1500 by 3000 feet. In the diorite located in the western fork maximum values of 800 to 900 ppm copper, 0.02 to 0.62 ppm gold, and 2 to 26 ppm molybdenum were obtained from an area of 1000 feet by 2000 feet.

Comment (Deposit): Model Name = Porphyry copper; porphyry copper-gold; porphyry copper-molybdenum (Cox and Singer, 1986; models 17, 20c, 21a)

References

Reference (Deposit): Fields, E.D., 1977, 1976 Annual report: Alaska search, Chignik area-Bristol Bay region: Bear Creek Mining Company, 44 p., 22 map sheets. (Report held by the Aleut Corporation, Anchorage, Alaska.)

Reference (Deposit): Cox, D.P., Detra, D.E., and Detterman, R.L., 1981, Mineral resource maps of the Chignik and Sutwik Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1053-K, 2 map sheets, scale 1:250,000.

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