Unnamed (east of West Fork Maclaren River) (ARDF #MH061) Cu

Unnamed (east of West Fork Maclaren River)

Prospect, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Ag
Ore minerals	chalcocite; malachite
Gangue minerals	epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale	MH
Quadrangle map, 1:63,360-scale	B-6
Latitude	63.2503
Longitude	-146.7004
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This prospect is in a cirque at an elevation of about 5,000 feet and about one-quarter mile south of the center of section 24, T. 19 S., R. 5 E., Fairbanks Meridian; it is about one-half mile southwest of peak 5590. This site corresponds to locality 17 on figure 4 of Cobb (1979 [OFR 79-238). The location is accurate within about one-quarter mile.

Geologic setting

Geologic description The rocks at this occurrence are mafic volcanic rocks of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). Chalcocite or its oxidation product malachite occurs in quartz-epidote veinlets, in vesicles partly filled with epidote, and on joint or other fracture surfaces of the volcanic rocks (Smith and others, 1973, 1975). Copper is typically accompanied by small amounts of silver.
Geologic map unit	(-146.702667044372, 63.2498642605576)
Mineral deposit model	Characteristic epigenetic mineralization of cupriferous volcanic rocks. Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number	23
Age of mineralization	The copper occurrence is epigenetic to the Nikolai Greenstone of Late Triassic age. It probably formed in Cretaceous or early Tertiary time (see MH060).

Production and reserves

Workings or exploration	The site was found during geochemical appraisal of the area (Smith and others, 1973, 1975).
Indication of production	None

References

References Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p. Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000. Smith, T.E., Kline, J.T., and Coursey, N.D., 1975, Analyses of stream-sediment samples, Mt. Hayes B-6 Quadrangle, south-central Alaska: Alaska Division of Geological & Geophysical Surveys Alaska Open-File Report 70, 2 p., 2 sheets, scale 1:63,360. Smith, T.E., Trible, T.C., and Stein, D.R., 1973, Analyses of rock and stream-sediment samples, Mt. Hayes A-6 quadrangle, south-central Alaska: Alaska Division of Geological and Geophysical Surveys Geochemical Report 26, 1 plate, scale 1:63,360. Stout, J.H., 1976, Geology of the Eureka Creek area, east-central Alaska Range: Alaska Division of Geological and Geophysical Surveys Geologic Report 46, 32 p., 1 plate, scale 1:63,360.
Reporters	W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date	7/30/2001