Fish

Prospect, Inactive

Alternative names

Collins and Stewart

Commodities and mineralogy

Main commodities Au
Other commodities Cu
Ore minerals chalcopyrite; gold; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-3
Latitude 60.8274
Longitude -148.1055
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located at an elevation of 800 feet, above the west shore of Esther Lake in the southwest portion of Esther Island. (It is reported to be one mile from shore.) The prospect is in the W1/2 section 31, T. 9 N., R. 8 E., of the Seward Meridian. This is location 89 of Condon and Cass (1958), location 85 of Cobb and Richter (1972), location 105 of MacKevett and Holloway (1977), location 168 of Cobb and Tysdal (1980), and location S-125 of Jansons and others (1984). This location is accurate to within half a mile.

Geologic setting

Geologic description

The prospect consists of a 40-foot adit in contact-metamorphosed slate and sandstone of the Valdez Group of Late Cretaceous age near the margin of the Esther pluton of Tertiary age (Cobb and Tysdal, 1980). The adit was driven on a 4- to 5-foot-wide shear that strikes N14E and dips 85W. The margin of the shear zone is well defined with abundant clay gouge. Quartz veins in the shear zone range in size from less than 4 inches to more than 2 feet in width and consists of bluish-white quartz containing chalcopyrite, pyrrhotite, and gold (Johnson, 1914 [B 592-G, p. 234-235]).
Fieldwork by the U.S. Bureau of Mines in 1979 failed to locate the adit. Their sample of a vertical, N25E, 40-inch-wide, pyrite-bearing quartz vein in the vicinity did not contain any significant metals values (Hoekzema and Sherman, 1983).
Geologic map unit (-148.107555417409, 60.8268033958639)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Tertiary or younger; the deposit in is a shear zone that cuts Tertiary granite.
Alteration of deposit Contact metamorphism.

Production and reserves

Workings or exploration A 40-foot adit was driven in 1912 (Johnson, 1914 [B 592-G, p. 234-235]). The U.S. Bureau of Mines searched for the prospect in 1979, but did not locate any workings. In the vicinity, they found and sampled a 40-inch-wide pyrite-bearing quartz vein striking N25E and dipping vertically. The vein assayed at 0.04 ppm gold, 0.2 ppm silver, 75 ppm copper, 5 ppm lead, 50 ppm zinc, and 30 ppm arsenic (Hoekzema and Sherman, 1983).
Indication of production None

References

MRDS Number A010385

References

Hoekzema, R.P., and Sherman, G.E., 1983, Mineral investigations in the Chugach National Forest, Alaska (Peninsula study area): U.S. Bureau of Mines in-house report; held at U.S. Bureau of Land Management Alaska State Office, Anchorage, 524 p.
Reporters Jeff A. Huber (Anchorage)
Last report date 2/4/2000