Unnamed (south of upper Eureka Creek)

Occurrence, Active

Commodities and mineralogy

Main commodities Cr
Ore minerals chromite
Gangue minerals olivine; serpentine

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.2539
Longitude -146.2215
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is approximately located at an elevation of 4,000 feet, on the north-facing slope of a hill one mile south of upper Eureka Creek, and at the center of section 21, T. 19 S., R. 8 E., Fairbanks Meridian. The occurrence corresponds to locality 45 in table 2 of Nokleberg and others (1991).

Geologic setting

Geologic description

The occurrence is in the Fish Lake ultramafic complex, a lopolithic feeder of basaltic flows of the Nikolai Greenstone of Late Triassic age (Wrangellia terrane) (Nokleberg and others, 1991). The occurrence consists of chromite disseminated in serpentinized olivine-rich cumulate. Grab sample 79ZN031A contained more than 5,000 parts per million chromium (Nokleberg and others, 1991, table 2).
Geologic map unit (-146.223759212707, 63.2534754509897)
Mineral deposit model Chromite disseminated in a layered mafic-ultramafic complex.
Age of mineralization Late Triassic, the age of the host rock.
Alteration of deposit Serpentinization.

Production and reserves

Workings or exploration The occurrence is covered by active Fort Knox Gold Resource claims.
Indication of production None