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  3. Alaska Resource Data File (ARDF)

Unnamed

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Ore minerals chalcopyrite
Gangue minerals pyrite

Geographic location

Quadrangle map, 1:250,000-scale SL
Quadrangle map, 1:63,360-scale C-6
Latitude 63.48
Longitude -171.81
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is 3 miles east of the mouth of the Moghoweyik River on western St. Lawrence Island. It is at an elevation of about 300 feet on the north side of the river valley and is probably located within 1/2 mile. It is locality 5 of Cobb (1972) and Cobb (1980) summarized relevant references under the name 'Unnamed occurrence'.

Geologic setting

Geologic description

Chalcopyrite mineralization (fracture fillings, veins, and disseminations) here is in the Sevuokuk pluton, a mid-Cretaceous (108 +/- 3.2 Ma) composite body that includes biotite hornblende quartz monzonite and biotite quartz monzonite phases (Csejtey, Patton, and Miller, 1971; Patton and Csejtey, 1980). At this site, pyrite and chalcopyrite are disseminated in biotite quartz monzonite. One grab sample contained 1,000 ppm copper, 15 ppm molybdenum, and 1.5 ppm silver (Patton and Csejtey, 1971, p. C8). Other characteristics of this site, such as size and alteration, have not been described.
Geologic map unit (-171.812792311113, 63.4790649099726)
Mineral deposit model Porphyry Cu? (Cox and Singer, 1986; model 17?).
Mineral deposit model number 17?
Age of mineralization Mid-Cretaceous, the age of the host Sevuokuk pluton (108 +/- 3.2 Ma; Patton and Csejtey, 1980).
Alteration of deposit Alteration has not been described.

Production and reserves

Workings or exploration One grab sample contained 1,000 ppm copper, 15 ppm molybdenum, and 1.5 ppm silver (Patton and Csejtey, 1971, p. C8).
Indication of production None

References

MRDS Number A015657

References

Cobb, E.H., 1972, Metallic mineral resources map of the Saint Lawrence quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-465, 1 sheet, scale 1:250,000.
Cobb, E.H., 1980, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in fifteen quadrangles in southwestern and west-central Alaska: U.S. Geological Survey Open-File Report 80-909, 103 p.
Csejtey, Bela, Jr., Patton, W.W., Jr., and Miller, T.P., 1971, Cretaceous plutonic rocks of St. Lawrence Island, Alaska, a preliminary report: U.S. Geological Survey Professional Paper 750-D, p. D68-D76.
Patton, W.W., Jr., and Csejtey, Bela, Jr., 1971, Preliminary geologic investigations of western St. Lawrence Island, Alaska: U.S. Geological Survey Professional Paper 684-C, p. C1-C15.
Patton, W.W., Jr., and Csejtey, Bela, Jr., 1980, Geologic map of St. Lawrence Island, Alaska: U.S. Geological Survey Miscellaneous Investigation Series Map I-1203, 1 sheet, scale 1:250,000.
Reporters Travis L. Hudson (Applied Geology)
Last report date 9/10/1998