West Fork-Post River

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu
Other commodities Zn
Ore minerals chalcopyrite; pyrrhotite; sphalerite

Geographic location

Quadrangle map, 1:250,000-scale MG
Quadrangle map, 1:63,360-scale A-2
Latitude 62.01
Longitude -153.88
Nearby scientific data Find additional scientific data near this location
Location and accuracy The West Fork-Post River occurrence is located on an east facing bluff of the west fork of Post River; it is at an elevation of approximately 4,000 feet (1,220 m) in the NE1/4 sec. 8, T. 22 N., R. 25 W., of the Seward Meridian. The occurrence, which corresponds to locality number 19 in Cobb (1972), is located to within 460 m.

Geologic setting

Geologic description

The West Fork-Post River occurrence consists of small lenses and disseminations of pyrrhotite associated with a swarm of northwest-trending mafic dikes that cut argillite of the Early to Late Silurian Terra Cotta Mountains Sandstone, a unit of the Dillinger subterrane (Bundtzen and others, 1988; Bundtzen, Harris, and Gilbert, 1997). Samples collected by Reed and Elliott (1968, C 596) contained semi-massive pyrrhotite and minor chalcopyrite and sphalerite. Values from selected grab samples on the surface run up to 45.7 grams/tonne silver, 1.50 percent copper, and 0.07 percent zinc.
Geologic map unit (-153.882230476209, 62.0093690663369)
Mineral deposit model Polymetallic vein (Cox and Singer, 1986; model 22c).
Mineral deposit model number 22c

Production and reserves

Workings or exploration The West Fork-Post River was discovered by the late Bruce Reed during mineral investigations for the U.S. Geological Survey in the 1960s (Reed and Elliott, 1968, C 596). Values from selected grab samples collected by Reed and Elliott (1968, C 596) contain up to 45.7 grams/tonne silver, 1.50 percent copper, and 0.07 percent zinc.
Indication of production None
Reserve estimates None.

Additional comments

Similar to Veleska-South prospect (MG050) in McGrath B-2 quadrangle.

References

MRDS Number A015041

References

Reporters T.K. Bundtzen (Pacific Rim Geological Consulting)
Last report date 10/30/1998