Unnamed (south of upper Sevenmile Lake)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Cu
Ore minerals azurite; bornite; chalcopyrite; malachite; pyrite
Gangue minerals calcite; epidote; quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale A-5
Latitude 63.176
Longitude -146.2138
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 4,400 feet, a quarter-mile south of upper Sevenmile Lake. It is in the center of the S1/2SE1/4 section 16, T. 20 S., R. 8 E., Fairbanks Meridian.

Geologic setting

Geologic description

This occurrence is in Nikolai Greenstone of Late Triassic age (Nokleberg and others, 1991), which was mapped as Boulder Creek volcanics by Stout (1976). The deposit consists of quartz-epidote-calcite veins that contain pyrite, chalcopyrite, bornite, and secondary azurite and malachite. The veins range from less than an inch to about 1 foot thick and occupy steep north- to northeast-trending faults and joints that cut and are not deformed by the Amphitheater syncline (Stout, 1976). The deposit was not sampled; silver is typically present in the copper deposits of the Nikolai Greenstone.
Geologic map unit (-146.216052276613, 63.1755730079151)
Mineral deposit model Basaltic Cu (Cox and Singer, 1986; model 23).
Mineral deposit model number 23
Age of mineralization The quartz veins are localized in north-northeast-trending faults and joints that cut across the folded limbs of the Amphitheater syncline. They postdate the folding, which is of Jurassic age, and are probably either Cretaceous, related to regional metamorphism and granitic plutonism (Nokleberg and others, 1986; Kurtak and others, 1992), or early Tertiary (Stout, 1976).

Production and reserves

Workings or exploration There are no significant workings at the site.
Indication of production None

References