Nugget

Prospect, Inactive

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Pb
Ore minerals chalcopyrite; galena; gold; pyrite; pyrrhotite
Gangue minerals calcite; chlorite; quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale D-3
Latitude 60.9771
Longitude -147.9581
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is at an elevation of 1,700 feet near the crest of the ridge about 1.2 miles northeast of Golden. It is in the NW1/4 section 12, T. 10 N., R. 8 E., of the Seward Meridian. This is location 99 of Condon and Cass (1958), location 81 of Cobb and Richter (1972), location 97 of MacKevett and Holloway (1977), location 155 of Cobb and Tysdal (1980), and location S-136 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The prospect is hosted in sheared sandstone and slate of the Upper Cretaceous Valdez Group. The deposit consists of one or more sulfide-bearing quartz veins in a shear zone that strikes N40E and dips 80 NW (Cobb and Tysdal, 1980). The workings on the prospect consist of a 160-foot adit at an elevation of 1,740 feet above sea level, a shallow shaft at an elevation of 1,800 feet, and surface trenches. The main vein, where exposed in the 1,740-level adit, ranges from 4 to 20 inches wide; it strikes N80E and dips 75N. Here, the shear zone is 4 to 30 inches wide. The vein contains some calcite and chlorite and is locally banded. Metallic minerals include chalcopyrite, galena, pyrite, and pyrrhotite (Johnson, 1914 [B 592-G, p. 220-221]).
The U.S. Bureau of Mines examined this property in 1979 and 1980 and collected 15 samples. The best assays were from the face of the 1,740-level adit and from a surface exposure at 1,800 feet elevation. The sample from the face contained 1.38 ounces of gold per ton, and the surface sample contained 29 ppm gold. The remainder of the samples contained less than 1 ppm gold. (Hoekzema and Sherman, 1983).
Geologic map unit (-147.960150737312, 60.9765332919412)
Mineral deposit model Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Cretaceous or younger; the deposit is in a shear zone the cuts rocks of the Valdez Group of Late Cretaceous age.

Production and reserves

Workings or exploration
Workings consist of a 160-foot adit at an elevation of 1,740 feet, a shallow shaft at an elevation of 1,800 feet, and trenches. The U.S. Bureau of Mines examined this property in 1979 and 1980, and collected 15 samples. The best assays were from the face of the 1,740-level adit and from a surface exposure at the 1,800 feet elevation. The sample from the face contained 1.38 ounces of gold per ton and the surface sample contained 29 ppm gold. The remainder of the samples contained less than one ppm gold (Hoekzema and Sherman, 1983).
A test shipment of ore was made in 1912 or 1913, but no results are reported (Johnson, 1914 [ B 592-G, p. 220-221]).
Indication of production Yes
Reserve estimates The U.S. Bureau of Mines estimated a geologic resource of 900 tons with a grade of 0.3 ounce of gold per ton (Hoekzema and Sherman, 1983).
Production notes A test shipment of ore was made in 1912 or 1913, but no results are reported (Johnson, 1914 [B 592-G, p. 220-221]).

References

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 1/10/2000