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Unnamed (Knight Island, east side of Mummy Bay)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite; pyrrhotite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SR
Quadrangle map, 1:63,360-scale A-3
Latitude 60.2202
Longitude -147.8098
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is located at or near tidewater about half way between Northeast Arm and Thumb Bay on the east side of Mummy Bay. It is near the center of section 36, T. 2 N., R. 9 E., of the Seward Meridian. This is location 249 of Tysdal (1978 [MF-880-A]) and S-31 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description

The occurrence consists of two 10-foot-wide shear zones that contain as much as 5 percent disseminated pyrrhotite and traces of chalcopyrite (Kurtak and Jeske, 1986). The zones trend N 10 E and dip 80 W. They are separated by 20 feet of unsheared greenstone. The zones have strong cataclastic textures, and some silicification is present near the shear margins (Kurtak and Jeske, 1986). Nelson and others (1985) mapped this area as Orca Group of early Tertiary age. A grab sample of the siliceous, sheared material contained 49 ppm copper and 14 ppm zinc (Kurtak and Jeske, 1986).
Geologic map unit (-147.811857156433, 60.2196305776957)
Mineral deposit model Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number 24a
Age of mineralization Tertiary or younger; the mineralization is in rocks of the Orca Group of Tertiary age.

Production and reserves

Workings or exploration No workings are reported. A single grab sample of the siliceous shear zone material carrying visible chalcopyrite and pyrrhotite contained 49 ppm copper, 4 ppm lead, and 14 ppm zinc (Kurtak and Jeske, 1986).
Indication of production None

References

MRDS Number A010559

References

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.
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 11/29/2001