Unnamed (along Kuskokwim River)

Occurrence in Alaska, United States with commodities Silver, Copper, Lead, Nickel

Geologic information

Identification information

Deposit ID 10307826
Record type Site
Current site name Unnamed (along Kuskokwim River)

Geographic coordinates

Geographic coordinates: -155.59093, 62.88745 (WGS84)
Relative position The unnamed occurrence is located along the banks of the Kuskokwim River about 8 kilometers due south of McGrath, Alaska and 1.5 kilometers due south of VABM About, at an elevation of about 400 feet (120 m) in the SE1/4 sec. 2, T. 32 N., R. 34 W., of the Seward Meridian. The occurrence corresponds to prospect #1 of Cobb (1972) and prospect #13 of Bundtzen and Laird (1983; field no. 77BT230).
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Copper Primary
Lead Primary
Nickel Secondary

Materials information

Materials Type of material
Pyrite Ore
Pyrrhotite Ore
Quartz Gangue


  • (Local) Ferricrete oxidation of pyrite and pyrrhotite.

Mineral occurrence model information

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

Nearby scientific data

(1) -155.59093, 62.88745

Comments on the geologic information

  • Geologic Description = This occurrence consists of pyrite-pyrrhotite nodules in highly deformed, sheared shale and siltstone of the Late Cretaceous Kuskokwim Group (Bundtzen and Laird, 1983). Individual sulfide nodules average about 8 centimeters in diameter, and are locally oxidized to ferricrete gossan. The sulfide bearing zone, which appears to be parallel to steeply dipping bedding in the host sedimentary rocks, is about 3 meters thick. The sulfide zone quickly extends upward into the vegetated slopes (Bundtzen and Laird, 1983). Cobb (1972) and Brooks and Martin (1921) refer to the occurrence as an unnamed, copper-nickel lode. A selected grab sample reported by Bundtzen and Laird (1983) contains 12.26 grams/tonne silver, 116 ppm copper, 167 ppm lead, and 139 ppm nickel.

Economic information

Economic information about the deposit and operations

Development status Occurrence

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Brooks and Martin (1921) first mentioned the existence of sulfide mineralization at the site. A selected grab sample reported by Bundtzen and Laird (1983) contains 12.26 grams/tonne silver, 116 ppm copper, 167 ppm lead, and 139 ppm nickel.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG007

Bibliographic references

  • Deposit

    Brooks, A.H., and Martin, G. C. 1921, The Alaska mining industry in 1919: U.S. Geological Survey Bulletin 714, p. 59-95.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.

  • Deposit

    Bundtzen, T.K., and Laird, G.M., 1983, Geologic map of the McGrath D-6 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 79, 1 sheet, scale 1:63,360.

Comments on the references

  • Primary Reference = Bundtzen and Laird, 1983

General comments

Subject category Comment text
Deposit Model Name = Polymetallic veins (Cox and Singer, 1986; model 22c).

Reporter information

Type Date Name Affiliation Comment
Reporter 25-NOV-98 T.K. Bundtzen Pacific Rim Geological Consulting