Unnamed (east of lower Eureka Glacier)

Occurrence, Active

Commodities and mineralogy

Main commodities Cr
Ore minerals chromite; magnetite
Gangue minerals calcite; chrysotile (brittle); opal; serpentine

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.3187
Longitude -146.2576
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of 4,700 feet about 2.25 miles east of lower Eureka Glacier. It is in the eastern headwaters of locally named Landslide Creek, a south-flowing tributary of Eureka Creek, and about one-half mile south-southwest of the center of section 29, T. 18 S., R. 8 E., Fairbanks Meridian. The occurrence corresponds to locality 41 in table 2 of Nokleberg and others (1991) and to locality 6 in figure 3 of Rose (1966 [ADMM GR 20]).

Geologic setting

Geologic description

This occurrence is in an Upper Triassic sill-like body of serpentinized dunite that can be traced continuously for more than 5 miles (Rose, 1966 [ADMM GR 20, figure 3]). The body is the main unit of the informally named Eureka ultramafic complex that occupies strands of the Broxson Gulch thrust fault (Nokleberg and others, 1991; W.T. Ellis, unpublished data, 1996).
The occurrence consists of veins and discontinuous lenses of opal, calcite, chrysotile, magnetite, chromite, and an unidentified green glassy mineral (Rose, 1966 [ADMM GR 20, p. 20]). Chromite is also disseminated in the dunite. No assay data are available.
Geologic map unit (-146.259865237542, 63.3182770897706)
Mineral deposit model Disseminated and vein-like masses of chromite in a mafic-ultramafic sill-like body.
Age of mineralization Late Triassic, the age of the host rock.
Alteration of deposit All of the ultramafic rock units are moderately to strongly serpentinized.

Production and reserves

Workings or exploration The occurrence is on active MAN Resources claims.
Indication of production None