Unnamed (ridge between middle and east forks in Broxson Gulch)

Occurrence, Active

Commodities and mineralogy

Main commodities Cr
Other commodities Pb
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 63.3429
Longitude -146.0845
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is at an elevation of about 4,900 feet on the ridge between the locally named middle fork and the east fork of the stream(s) in Broxson Gulch (see figure 2 of Rose, 1965). The occurrence is in the SE1/4NE1/4 section 19, T. 18 S., R. 9 E., Fairbanks Meridian; it corresponds to locality 46 in table 2 of Nokleberg and others (1991).

Geologic setting

Geologic description

A fault-bottomed block of Upper Triassic cumulate gabbro and melagabbro overlies the Slana Spur Formation of Late Paleozoic age at this site (Rose, 1965, figure 2; Nokleberg and others, 1991). The olivine cumulate contains disseminated chromite. Sample 79NK009A of the cumulate assayed more than 5,000 parts per million chromium (Nokleberg and others, 1991, locality 46, table 2). Stream-sediment sample 282 collected a few hundred feet north of the site was moderately anomalous in lead (Rose, 1965).
Geologic map unit (-146.086765525158, 63.3424807867468)
Mineral deposit model Chromite disseminated in layered mafic-ultramafic complex.
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