Unnamed (east side of the 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 A-6
Latitude 63.2371
Longitude -146.7373
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is approximately located on the east side of the West Fork Maclaren River at an elevation of about 3,500 feet, in the NE1/4SW1/4 section 26, T. 19 S., R. 5 E., Fairbanks Meridian. The site corresponds to locality 16 in figure 4 of Cobb (1979 [OFR 79-238]) and to locality 22 in table 2 of Nokleberg and others (1991).

Geologic setting

Geologic description

The rock at the prospect is propylitized metabasalt of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). The deposit consists of malachite or chalcocite in quartz-epidote veinlets, in vesicles, or on fracture or joint surfaces in the metabasalt (Saunders, 1961 [report for the year]). No assay data are available; small amounts of silver typically occur with the copper deposits of the Nikolai Greenstone.
Geologic map unit (-146.73956695998, 63.2366629523443)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization Probably Cretaceous (Nokleberg and others, 1986) or early Tertiary (Stout, 1976); see MH060 and MH100.
Alteration of deposit Propylitic alteration of metabasalt; oxidation of iron- and copper-bearing minerals.

Production and reserves

Workings or exploration Copper occurrences were found during geologic investigations in about 1960; there are no known workings.
Indication of production None