BGM Breccia

Occurrence, Active

Commodities and mineralogy

Main commodities Cu; Ni; Pd; Pt
Ore minerals chalcopyrite; pentlandite; pyrite; pyrrhotite
Gangue minerals serpentine

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.3222
Longitude -146.0654
Nearby scientific data Find additional scientific data near this location
Location and accuracy The BGM Breccia occurrence is at an elevation of 4,500 feet in the headwaters of an unnamed east tributary to the east fork of the stream in Broxson Gulch, about 800 feet north-northeast of peak 4825 in the SE1/4SW1/4 section 29, T. 18 S., R. 9 E., Fairbanks Meridian.

Geologic setting

Geologic description

The Airstrip Fault (Rose 1965, figure 2) is subparallel to the gulch that hosts this occurrence. Rocks south of the fault include Upper Triassic melagabbro and peridotite. Float in the upper creek contains mineralized magmatic-breccia cobbles and boulders with dunite and gabbro clasts in a coarse-grained pyroxene-rich matrix (W.T. Ellis, unpublished data, 1996). A grab sample of breccia containing about 4 percent total sulfide assayed 0.43 percent copper, 0.88 percent nickel, 412 parts per billion (ppb) palladium, and 245 ppb platinum. Pyrrhotite is the dominant sulfide, along with minor pentlandite, pyrite, and chalcopyrite. The ultramafic host rocks are serpentinized.
Geologic map unit (-146.06766338786, 63.3217804173675)
Mineral deposit model Ni-Cu-PGE in differentiated mafic-ultramafic sill.
Age of mineralization Late Triassic, the age of the host breccia.
Alteration of deposit The ultramafic host rocks are strongly serpentinized.

Production and reserves

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



Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 6/19/2001