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