Sedanka Island

The Sedanka Island is a zinc, gold, silver, and copper mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Sedanka Island
Secondary: Biorka

Commodity

Primary: Zinc
Primary: Gold
Primary: Silver
Primary: Copper
Secondary: Cadmium
Secondary: Lead

Location

State: Alaska
District: Aleutians

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Polymetallic veins

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Christie (1974) reports pervasive development of chlorite and minor sericite and quartz veinlets near diorite.

Rocks

Name: Diorite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Pliocene

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

Name: Diorite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

Name: Diorite
Role: Associated
Age Type: Host Rock
Age Young: Pliocene

Analytical Data

Not available

Materials

Ore: Galena
Ore: Silver
Ore: Sphalerite
Ore: Gold
Ore: Chalcopyrite
Gangue: Quartz
Gangue: Pyrite
Gangue: Ankerite

Comments

Comment (Workings): Workings / Exploration = A 70 by 12 m area of tundra overburden was stripped by hydraulic methods and explosives, and 29 channel samples collected along strike of deposit for 75 m during USBM investigations in 1945 (Webber and others, 1946). Average analysis of 29 samples along narrow mineralized zone was 6.8 percent Zn. Average of 19 samples was 9.1 percent Zn, 0.24 percent Pb, 0.45 percent Cu, 0.04 oz/ton Au, 1.4 oz/ton Ag. Benefication tests showed that concentrates contained 0.3 percent Cd. Sampling in 1979 by Resource Associates of Alaska (Butherus, 1979) produced gold values ranging from 200 ppb to 12 ppm (0.348 oz/t). Christie (1974) did not visit the 'zinc' occurrence, however reconnaissance mapping in the area and limited sampling resulted in samples yielding up to 205 ppm copper, 1,000 ppm zinc, 3.1 ppm silver, and 0.34 ppm gold.

Comment (Geology): Geologic Description = Quartz and ankerite in nearly vertical veins in N 60xW striking fractures in diorite that forms hanging wall of fault that strikes N 80xE and dips 55xS. Richest mineralization near fault; fine-grained greenstone of footwall is barren. Veins contain sphalerite, abundant pyrite, a small amount of chalcopyrite and argentiferous(?) galena, and a small amount of gold. Pyrite also disseminated throughout diorite. Deposit along fault has been exposed for 70 m along strike, with mineralization zone a maximum of 18 m high and averaging more than 13 meters. Ore shoot extends at least 14 m beyond sampled zone, with fault traceable for at least 900 m west, and possibly 3.2 km east of mineralized zone, but no mineralization has been detected outside of the sampled area. Ores deposited at temperature below 138x C (Drewes and others, 1961, p. 658).

Comment (Deposit): Model Name = Polymetallic vein

Comment (Reference): Primary Reference = Webber and others, 1946

Comment (Commodity): Ore Material = argentiferous galena

Comment (Exploration): Status = Inactive

References

Reference (Deposit): Bain, H.F., 1946, Alaska's minerals as a basis for industry: U.S. Bureau of Mines Information Circular 7379, 83 p.

Reference (Deposit): Twenhofel, W.S., 1953, Potential Alaskan mineral resources for proposed electrochemical and electrometallurgical industries in the upper Lynn Canal area, Alaska: U.S. Geological Survey Circular 252, 14 p.

Reference (Deposit): Drewes, Harold, Fraser, G.D., Snyder, G.L., and Barnett, H.F., Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-S, p. 583-676.

Reference (Deposit): Webber, B.S., Moss, J.M., and Rutledge, F.A., 1946, Exploration of Sedanka zinc deposit, Sedanka Island, Alaska: U.S. Bureau of Mines Report of Investigations 3967, 15 p.

Reference (Deposit): Butherus, D.L., Gressitt, E.E., Pray, Jim, Corner, N.G., Lindberg, P.A., and Fankhauser, R.E., 1979, Exploration and evaluation of the Aleut Native Corporation Lands 1979: Unpublished Resource Associates of Alaska report prepared for Houston Oil and Minerals Corporation and available from The Aleut Corporation, 69 p., 1 appendix.

Reference (Deposit): Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Unalaska quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies MF-446, 1 sheet, scale 1: 250,000.

Reference (Deposit): Randolph, D.B., 1991, Unalaska project, 1990 final report: Battle Mountain Exploration Company, Alaska District, 62 p., 5 appendices, 15 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)

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