Unnamed (east of headwaters of Windy Fork)

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

Geologic information

Identification information

Deposit ID 10307871
Record type Site
Current site name Unnamed (east of headwaters of Windy Fork)

Geographic coordinates

Geographic coordinates: -153.92881, 62.01247 (WGS84)
Relative position This unnamed occurrence is located on a moderately steep, southeast facing spur overlooking the headwaters of the west fork of Post River. It is about 3 kilometers east of the headwaters of the Windy Fork of the Kuskokwim River, at an elevation of 5,050 feet (1,540 m), in the NE1/4 sec. 7, T. 22 N., R. 25 W., of the Seward Meridian. The reporter sampled the site in 1982.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Silver Primary
Zinc Primary
Copper Secondary
Lead Secondary

Materials information

Materials Type of material
Pyrite Ore

Alteration

  • (Local) None.

Mineral occurrence model information

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

Nearby scientific data

(1) -153.92881, 62.01247

Comments on the geologic information

  • Geologic Description = The unnamed occurrence consists of shale-hosted Zn-Ag (Pb-Cu) mineralization in the Lower Ordovician to Lower Silurian Post River Formation, a unit of the Dillinger subterrane (Bundtzen, Harris, and Gilbert, 1997). The mineralized zone is parallel to bedding and is a distinctly sulfur-stained, carbonaceous shale bed about one meter thick. Only disseminated pyrite was identified in the zone. Although isotopic data is lacking, Bundtzen, Harris, and Gilbert (1997) regarded the occurrence as possible sedimentary exhalitive (?) lead-zinc mineralization. Two random grab samples from the mineralized shale contained up to 0.86 percent zinc, 4.5 grams/tonne silver, 104 ppm copper, and 186 ppm lead (Bundtzen and others, 1988).
  • Age = Inferred to be Lower Ordovician to Lower Silurian (Bundtzen, Harris, and Gilbert, 1997), assuming it is a syngenetic deposit.

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 and Kristi McDonald sampled the mineralized zone in 1982. Two random grab samples from the mineralized shale yielded up to 0.86 percent zinc, 4.5 grams/tonne silver, 104 ppm copper, and 186 ppm lead (Bundtzen and others, 1988).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Alaska Resource Data File ARDF MG074

Bibliographic references

  • Deposit

    Bundtzen, T.K., Kline, J.T., Smith, T.E., and Albanese, M.D., 1988, Geology of the McGrath A-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 91, 18 p., 1sheet, scale 1:63,360.

  • 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 p., 1 sheet, scale 1:125,000.

Comments on the references

  • Primary Reference = Bundtzen and others, 1988

General comments

Subject category Comment text
Deposit Model Name = Sedimentary exhalitive lead-zinc (Cox and Singer, 1986; model 31b).
Deposit Other Comments = See other examples of shale-hosted mineralization in McGrath quadrangle (MG029, MG049, MG051, MG064, MG071).

Reporter information

Type Date Name Affiliation Comment
Reporter 09-DEC-98 T.K. Bundtzen Pacific Rim Geological Consulting