Sweepstake; Sweepstake Mining Co. Mine, Prince William Sound Mining District, Valdez-Cordova Census Area, Alaska, USAi

Regional Level Types
Sweepstake; Sweepstake Mining Co. Mine	Mine
Prince William Sound Mining District	Mining District
Valdez-Cordova Census Area	Census Area
Alaska	State
USA	Country

Location: The Sweepstake mine portal is at an elevation of 550 feet above the southeast shore of Harriman Fiord. The mine is located in the NE1/4 section 9, T. 10 N., R. 6 E., of the Seward Meridian. This is location 125 of Tysdal (1978 [MF-880-A]) and location S-152 of Jansons and others (1984). This location is accurate to within a quarter of a mile.
Geology: The host rock at the Sweepstake mine is graywacke and slate of the Valdez Group of Late Cretaceous age (Nelson and others, 1985), which is cut by numerous Eocene felsic dikes from 6 to 48 inches thick (Johnson 1914 [B 592-G, p. 229]). The mineralization consists of a quartz-carbonate vein carrying arsenopyrite, chalcopyrite, galena, pyrite, sphalerite, stibnite, and gold. The vein is well exposed for about 150 feet and varies in width from 1 to 5 feet. It strikes east and dips 85N at its upper end and strikes N84W and has a vertical dip at the lower exposure. Near the portal, the vein thins to stringers of quartz-carbonate that cement shattered dike rock (Johnson, 1914 [B 592-G, p. 229]. The workings consist of a 170-foot adit, and surface trenches. A 1,800-foot tramway connects the mine to a two-stamp mill near tidewater (Hoekzema and Sherman, 1983). The U.S. Bureau of Mines collected six chip and grab samples from the mine and dump that contained from trace to 0.08 ounce of gold per ton and from 0.01 to 0.09 ounce of silver per ton. The best sample was a 14-inch chip sample from about 75 feet away from the mouth of the portal. This sample consisted of a quartz-carbonate vein stained by malachite (Hoekzema and Sherman, 1983).
Workings: The workings consist of a 170 foot adit, and surface trenches. Improvements include a 1,800-foot tramway and a two-stamp mill. Neither the mill nor tramway was ever used (Johnson, 1914 [B 592-G, p. 229]). In 1937, V. Hackett and E. Fultz erected a Straub Mill on the property and milled 25 tons of ore with a estimated grade of 0.33 to 0.43 ounce of gold per ton. The mine was abandoned due to the the low tenor of the ore ( Roehm, 1936 [IR195-13]).
Age: Eocene or younger; the vein cuts Eocene felsic dikes.
Production: Total estimated production is 25 tons of ore having an estimated grade of 0.33 to 0.43 ounce of gold per ton gold (Roehm, 1936 [IR195-13]). There was no record of any other production (Jansons and others, 1984).
Reserves: The U.S. Bureau of Mines estimates a resource of 2,325 tons grading 0.01 ounce of gold per ton (Hoekzema and Sherman, 1983).

Commodities (Major) - Au; (Minor) - Cu, Pb, Sb, Zn
Development Status: Yes; small
Deposit Model: Low-sulfide Au-quartz vein (Cox and Singer, 1986; model 36a)

Other Databases

Link to USGS - Alaska:	SR072

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References