Unnamed (on tributary to Middle Fork of Kuskokwim River)

Occurrence in Alaska, United States with commodities Silver, Copper, Lead, Iron, Molybdenum, Nickel, Vanadium, Zinc

Geologic information

Identification information

Deposit ID 10307842
Record type Site
Current site name Unnamed (on tributary to Middle Fork of Kuskokwim River)

Geographic coordinates

Geographic coordinates: -154.45184, 62.20946 (WGS84)
Relative position This unnamed occurrence is located near the juncture of two second order tributaries to an unnamed stream draining into Middle Fork of Kuskokwim River. It is at an elevation of 2,700 feet (823 m) in the SW1/4 sec. 34, T. 25 N., R. 28 W., of the Seward Meridian. The reporter visited the site in 1998; at station no. 98BT441.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Copper Primary
Lead Primary
Iron Secondary
Molybdenum Secondary
Nickel Secondary
Vanadium Secondary
Zinc Secondary

Materials information

Materials Type of material
Galena Ore
Marcasite Ore
Pyrite Ore
Sericite Gangue

Mineral occurrence model information

Model code 212
USGS model code 31b
Deposit model name Bedded barite

Nearby scientific data

(1) -154.45184, 62.20946

Comments on the geologic information

  • Geologic Description = The unnamed occurrence consists of stratiform pyrite-marcasite-galena bands parallel to sedimentary bedding in black, carbonaceous shale of the Lower Ordovician to Lower Silurian, Post River Formation, a unit of the Dillinger subterrane (Gilbert and others, 1988; Bundtzen, Harris, and Gilbert, 1997). The mineralization occurs in several outcrops at creek level that can be traced for about 75 meters; the sulfide-bearing bands are about 3 meters thick. However, individual sulfide-bearing layers are rarely more than 5 centimeters thick, and are isoclinally deformed as are the sedimentary interlayers. Microprobe analysis showed galena grains impregnated in the pyrite-rich layers. . One grab sample of massive pyrite-marcasite-galena mineralization contained 2.4 grams/tonne silver, 135 ppm copper, 11.60 percent iron, 39 ppm molybdenum, 255 ppm nickel, 176 ppm lead, 168 ppm vanadium, and 208 ppm zinc.
  • Age = Lower Paleozoic if mineralization is syngenetic.

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 = The reporter investigated the site in 1998 (T.K. Bundtzen and G.M. Laird, written communication, 1998). One grab sample of massive pyrite-marcasite-galena mineralization contained 2.4 grams/tonne silver, 135 ppm copper, 11.60 percent iron, 39 ppm molybdenum, 255 ppm nickel, 176 ppm lead, 168 ppm vanadium, and 208 ppm zinc.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG029

Bibliographic references

  • Deposit

    Gilbert, W.G., Solie, D.N., and Kline, J.T., 1988, Geologic map of the McGrath A-3 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 92, 2 sheets, 1:63,360 scale.

  • Deposit

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

Comments on the references

  • Primary Reference = This description

General comments

Subject category Comment text
Deposit Model Name = Sedimentary exhalitive lead-zinc (?) (Cox and Singer, 1986; model 31b).
Deposit Other Comments = See other possible sedimentary exhalitive prospects in McGrath quadrangle (MG049, MG051, MG064, MG071, MG072, MG074).

Reporter information

Type Date Name Affiliation Comment
Reporter 22-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting