Unnamed (tributary to West Fork Maclaren River)

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 63.1843
Longitude -146.8018
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 5,000 feet along an east-flowing tributary of the West Fork Maclaren River. The occurrence is in the SE1/4NW1/4 section 16, T. 20 S., R. 5 E., Fairbanks Meridian, and corresponds to locality 7 in figure 4 of Cobb (1979 [OFR 79-238]).

Geologic setting

Geologic description

The rock of this occurrence is metabasalt of the Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991). The deposit consists of malachite and chalcocite in quartz-epidote veins, in vesicles, and on fracture and joint surfaces in propylitized basalt (Smith and others, 1973). No samples were collected at this site, but small amounts of silver commonly occur in the copper deposits of the Nikolai Greenstone.
Geologic map unit (-146.804064360653, 63.1838603603562)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization The deposit is probably Cretaceous or early Tertiary in age (see MH060 and MH100).
Alteration of deposit Propylitic alteration.

Production and reserves

Workings or exploration The deposit was discovered during regional reconnaissance; there are no workings.
Indication of production None