Unnamed (north of Coal Creek) (ARDF #MH040) Cu

Unnamed (north of Coal Creek)

Occurrence, 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	A-6
Latitude	63.1863
Longitude	-146.9364
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	This occurrence is at an elevation of about 4,500 feet on the south side of the ridge north of Coal Creek. The occurrence is in the NE1/4 section 15, T. 20 S., R. 4 E., Fairbanks Meridian. It is an approximate location that may correspond to locality 4 in figure 4 of Cobb (1979 [OFR 79-238]).

Geologic setting

Geologic description The rock at this site is the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). The occurrence is one of several copper in basalt occurrences reported by Smith and others (1973, 1975). Copper, accompanied by epidote and quartz, occurs in primary chalcocite and secondary malachite in vesicles, veinlets, and on fracture surfaces. The host rock is propylitized.
Geologic map unit	(-146.938664122672, 63.1858573592053)
Mineral deposit model	Basaltic (greenstone) Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number	23
Age of mineralization	Probably Cretaceous or early Tertiary (see MH060).
Alteration of deposit	Propylitic alteration.

Production and reserves

Workings or exploration	This occurrence was found during mapping and reconnaissance sampling (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.
Reporters	W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date	8/1/2001