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Old Harbor

Prospect, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale KD
Quadrangle map, 1:63,360-scale A-5
Latitude 57.14
Longitude -153.34
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is located on the northwest side of Sitkalidak Island approximately 5 miles south of Old Harbor (Berg and Cobb, 1967, figure 15, locality 14; Cobb, 1972, MF 460, locality 6; MacKevett and Holloway, 1977, locality 6).

Geologic setting

Geologic description

A sulfide-bearing shear zone is present along a footwall contact between a gabbro sill and Cretaceous metasedimentary rock. The shear zone is 10 to 20 feet in width and extends for approximately 2500 feet. Pyrite, pyrrhotite, and sparse chalcopyrite are disseminated in the shear zone. In addition, several sulfide masses containing abundant chalcopyrite occur about 1250 feet apart. Assays range from 0.9 percent copper in the disseminated mineralization to 5.52 percent in the chalcopyrite-rich zones (Berg and Cobb, 1967, p. 87).
Geologic map unit (-153.342253684414, 57.1392139661223)
Mineral deposit model Shear zone with minor copper values.
Age of mineralization Cretaceous or younger

Production and reserves

Workings or exploration Assays range from 0.09 percent copper in disseminated material to 5.52 percent copper in one chalcopyrite-rich mass. The shear zone was prospected by 3 short adits prior to WW II.
Indication of production None

Additional comments

Site is on land conveyed to the Koniag Corporation.

References

MRDS Number A015093

References

Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Kodiak quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-460, 1 map sheet, scale 1:250,000.
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Afognak, Karluk, Kodiak, and Trinity Islands quadrangles, Alaska: U.S. Geological Survey Open-File Report 79-860, 49 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000.
Reporters S.H. Pilcher (Anchorage)
Last report date 10/12/1998