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  3. Alaska Resource Data File (ARDF)

Unnamed (east side of Knight Island)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu; Zn
Ore minerals chalcopyrite; pyrrhotite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale B-2
Latitude 60.2839
Longitude -147.708
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is located near tidewater, about 3 miles southwest of the mouth of Marsha Bay. It is in the NW1/4 section 10, T. 2 N., R. 10 E., of the Seward Meridian. This is location 141 of MacKevett and Holloway (1977), location 239 of Cobb and Tysdal (1980), and location S-41 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The country rock is slate, graywacke, and greenstone of the Orca Group of early Tertiary age (Nelson and others, 1985). Greenstone encloses slate lenses less than 50 feet long and more than 20 feet wide. These lenses contain as much as 1 percent chalcopyrite. A 25-foot-wide tuffaceous zone in the greenstone contains as much as 5 percent chalcopyrite (Kurtak and Jeske, 1986). A greenstone-slate breccia zone with a quartz matrix contained a trace of chalcopyrite. Tysdal (1978 [MF-880-A]) reported one mineralized zone, 7.5 meters wide and 9 meters long, containing quartz, chalcopyrite, pyrrhotite, and sphalerite.
A 20-foot-wide random chip sample of a 20-foot-wide mineralized slate lens contained 480 ppm copper and 580 ppm zinc. A 25-foot-wide random chip sample of the tuffaceous zone contained 0.24 percent copper and 1.1 percent zinc (Kurtak and Jeske, 1986). The greenstone-slate breccia zone was not sampled.
Geologic map unit (-147.710026654687, 60.2833184831363)
Mineral deposit model Besshi massive sulfide (Cox and Singer, 1986; model 24b)
Mineral deposit model number 24b
Age of mineralization Tertiary or younger; the occurrence is in rocks of the Orca Group of Tertiary age.
Alteration of deposit Greenstone is altered basalt.

Production and reserves

Workings or exploration A 20-foot-wide random chip sample of the mineralized slate unit contained 480 ppm copper and 580 ppm zinc. A 25-foot-wide random chip sample of the tuffaceous zone contained 0.24 percent copper and 1.1 percent zinc (Kurtak and Jeske, 1986). The greenstone-slate breccia zone was not sampled. No workings or improvements are reported.
Indication of production None

References

MRDS Number A010566

References

Cobb, E.H., and Tysdal, R.G., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Blying Sound and Seward quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-621, 276 p.
Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000.
Kurtak, J.M., and Jeske, R.E., 1986, Mineral investigations in the Chugach National Forest, Alaska (Islands area): U.S. Bureau of Mines Open-File Report 54-86, 302 p., 1 sheet, scale 1:63,360.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000.
Tysdal, R.G., 1978, Mines, prospects, and occurrences map of the Seward and Blying Sound quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-880-A, 2 sheets, scale 1:250,000.
Reporters Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date 9/9/2001