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Unnamed

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Ag
Ore minerals chalcopyrite; pyrite
Gangue minerals magnetite

Geographic location

Quadrangle map, 1:250,000-scale UN
Quadrangle map, 1:63,360-scale C-1
Latitude 53.75
Longitude -166.1667
Nearby scientific data Find additional scientific data near this location
Location and accuracy East side of Sedanka Island. Anomaly no. 25 of Christie (1974).

Geologic setting

Geologic description

Color anomaly 6,000 ft (1800 m) by 2,000 ft (600 m) occurs in volcanic rocks of the Unalaska Formation (see Drewes and others, 1961). In the east half of the area, scattered, intensely altered zones of pyrite-chlorite +/- epidote are separated by zones of moderate alteration containing minor pyrite and abundant fracture-controlled magnetite and epidote. According to Christie (1974), the only possible intrusive rocks are intensely bleached and contain 3 to 10 percent pyrite. Chalcopyrite is minor and sporadic in occurrence, where present it occurs as fracture fillings and disseminated in both weakly and intensely altered rock. Where chalcopyrite does occur, grade is less than 200 ppm. Fracturing is weak to moderately developed.
Geologic map unit (-166.168609545671, 53.7491577976732)
Mineral deposit model Copper porphyry?
Mineral deposit model number 17
Age of mineralization Miocene or younger
Alteration of deposit Propylitic alteration having the assemblages pyrite-chlorite +/- epidote and magnetite-epidote +/- chlorite. Christie (1974) reported leaching is weakly developed. Intensely bleached rocks containing up to 10 percent pyrite are locally present. (Possible sericitic alteration?).

Production and reserves

Workings or exploration Brief reconnaissance mapping and a few soil/silt samples showed low level anomalies, most significant was 1.3 to 1.4 ppm silver.
Indication of production None

Additional comments

See UN005, Sedanka, which occurs to the northwest of this occurrence.

References

MRDS Number A106014

References

Christie, J.S., 1974, Aleut-Quintana-Duval 1974 joint venture, final report: Unpublished Quintana Minerals Corporation report, 24 p., 3 appendices, 2 maps. (Report held by the Aleut Corporation, Anchorage, Alaska.)
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.
Reporters Damon Bickerstaff, F.H. Wilson
Last report date 5/8/1996