Swetmann

Prospect, Inactive

Commodities and mineralogy

Main commodities Ag; Au
Other commodities Cu; Pb
Ore minerals arsenopyrite; azurite; chalcopyrite; chalcocite; galena; gold; malachite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale C-7
Latitude 60.6082
Longitude -149.5878
Nearby scientific data Find additional scientific data near this location
Location and accuracy The prospect is located in the SW1/4 section 14, T. 6 N., R. 2 W., of the Seward Meridian. It is at an elevation of 3,200 to 3,850 feet, on the north side of Slate Creek about 1.5 miles west of the Seward Highway. This is location 25 of Cobb and Richter (1972), location 36 of MacKevett and Holloway (1977), location 53 of Cobb and Tysdal (1980), and location S-251 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

This deposit consists of a locally oxidized, auriferous, sulfide-bearing quartz vein in interbedded metasiltstone and sandstone of the Valdez Group of Late Cretaceous age (Tuck, 1933). The quartz vein ranges in width from 10 to 16 inches; it strikes N5W and dips 60N, parallel to the cleavage of the country rock. The footwall of the vein is massive graywacke, and the hanging wall is somewhat slaty. The vein apparently occupies a shear zone. The vein material is predominantly quartz that carries small amounts of arsenopyrite, pyrite, chalcopyrite, and galena. Secondary copper minerals including malachite, azurite, and possibly chalcocite occur locally.
Geologic map unit (-149.589957900183, 60.6076318992219)
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; vein cuts rocks of the Valdez Group of Late Cretaceous age.
Alteration of deposit Local oxidation of copper minerals.

Production and reserves

Workings or exploration
Workings consist of a partly caved, 120-foot adit at 3,700 feet elevation, a caved 260-foot adit at 3,200 feet elevation, and prospect pits (Jansons and others, 1984). There is a discovery pit above the adits. The 260-foot adit is 500 feet below the discovery and was intended to intercept the vein but never did. The 120-foot adit intersects the vein 60 feet below the outcrop (Tuck, 1933).
A channel sample 16 inches long across the vein at the discovery pit assayed 0.16 ounce of gold per ton, and another channel sample 12 inches long assayed 0.03 ounce of gold per ton and silver at 0.2 ounce per ton (Tuck, 1933). The U.S. Bureau of Mines collected two samples in 1982 that assayed 0.005 ounce of gold per ton and trace amounts of silver (Hoekzema and Sherman, 1983).
Indication of production None

References

MRDS Number A010553

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 1/8/2000