Unnamed (head of South Fork Kuskokwim River)

Occurrence in Alaska, United States with commodities Silver, Copper

Geologic information

Identification information

Deposit ID 10002170
MRDS ID A013067
Record type Site
Current site name Unnamed (head of South Fork Kuskokwim River)

Geographic coordinates

Geographic coordinates: -153.32276, 61.56808 (WGS84)
Relative position This occurrence is at an elevation of about 6,200 feet on a ridge along the east side of the southeast headwater tributary of South Fork Kuskokwim River. The map site is 0.4 mile south-southwest of peak 6980, in the northeast corner of section 17, T 17 N, R 22 W, of the Seward Meridian. This is locality Cobb (1972 [MF 412]; 1976 [OF 76-485]). The location is probably accurate to within a quarter of a mile.
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Geographic areas

Country State
United States Alaska


Commodity Importance
Silver Primary
Copper Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Quartz Gangue


  • (Local) Quartz veining.

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 Associated
    Rock type Plutonic Rock > Granitoid > Quartz Monzonite
    Stratigraphic age (youngest) Pliocene
    Stratigraphic age (youngest) Pliocene
  • Host or associated Host
    Rock type Plutonic Rock > Granitoid > Quartz Monzonite

Nearby scientific data

(1) -153.32276, 61.56808

Comments on the geologic information

  • Geologic Description = Reed and Elliott (1970) reported that sparse fractures as much as 1 cm wide in quartz monzonite are filled with quartz, chalcopyrite, pyrite, and traces of other sulfide minerals. Pyrite and chalcopyrite are also disseminated in the quartz monzonite. A sample of a vein contained greater than 20,000 ppm copper, 100 ppm silver, and anomalous lead. The mineralized quartz monzonite is Tertiary; it intrudes upper Mesozoic slate and graywacke as well as older, probably Cretaceous, granitic rocks (Cobb and Reed, 1981).
  • Age = Tertiary. Quartz veins and mineralization crosscut Tertiary intrusive rocks.

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Reconnaissance sampling has been completed in this area (Reed and Elliott, 1970).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013067
USGS Alaska Resource Data File ARDF LH019

Bibliographic references

  • Deposit

    Cobb, E.H., and Reed, B.L., 1981, Summaries of data on and lists of references to metallic and selected nonmetallic mineral occurrences in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska; Supplement to Open-File Report 76-485; Part A, Summaries to January 1, 1981: U.S. Geological Survey Open-File Report 81-1343-A, 25 p.

  • Deposit

    Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Iliamna, Lake Clark, Lime Hills, and McGrath quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-485, 101 p.

  • Deposit

    Reed, B.L., and Elliott, R.L., 1970, Reconnaissance geologic map, analyses of bedrock and stream sediment samples, and an aeromagnetic map of parts of the southern Alaska Range: U.S. Geological Survey Open-File Report 70-217, 145 p., 1 sheet, scale 1:250,000. (Also published as U.S. Geological Survey Open-File Report 413).

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Lime Hills quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-412, 1 sheet, scale 1:250,000.

Comments on the references

  • Primary Reference = Reed and Elliott, 1970

General comments

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

Reporter information

Type Date Name Affiliation Comment
Reporter 10-JUN-2001 Travis L. Hudson Applied Geology
Reporter 10-JUN-2001 Travis L. Hudson Applied Geology