Unnamed (west of West Fork Maclaren River)

Occurrence, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-6
Latitude 63.2254
Longitude -146.8007
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 4,300 feet on the south side of an east-flowing tributary to the West Fork Maclaren River, in the SE1/4 NW1/4 section 33, T. 19 S., R. 5 E., Fairbanks Meridian. The occurrence corresponds to locality 11 in figure 4 of Cobb (1979 [OFR 79-238]) and to locality 16 in table 2 of Nokleberg and others (1991).

Geologic setting

Geologic description

The rock at this occurrence is propylitized basalt and andesite of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1982, 1991). Mineral deposits at the occurrences are quartz-epidote veins from 2 to 6 inches wide in a minor fault zone. The veins contain local concentrations of primary chalcocite, pyrrhotite, covellite (?), and secondary malachite (Smith and others, 1973, location B). Copper deposits hosted in the Nikolai Greenstone typically contain small amounts of silver.
Geologic map unit (-146.80296716612, 63.2249610950952)
Mineral deposit model Basaltic 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 Nikolai Greenstone is propylitized.

Production and reserves

Workings or exploration Natural outcrops and float.
Indication of production None

References

References

Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 8/3/2001