Unnamed (south of Black Rapids Roadhouse)

Prospect, Inactive

Commodities and mineralogy

Main commodities Sb
Ore minerals pyrite; stibnite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale C-4
Latitude 63.5085
Longitude -145.8525
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is at an elevation of 2,400 feet 1.5 mile south of the Black Rapids Roadhouse (Rapids Club). It is east of the Richardson Highway at the north edge of a small lake about the same elevation as the highway (Ebbley and Wright, 1948) in the SE1/4SW1/4 section 20, T. 16 S., R. 9 E., Fairbanks Meridian. The prospect corresponds to locality 7 of Cobb (1979 [OFR 79-238]) and locality N12 in table 1 of Nokelberg and others (1991). The location is accurate within a quarter mile.

Geologic setting

Geologic description

This prospect consists of stibnite and pyrite in nearly vertical quartz veins that strike N70E. The veins cut quartz-white mica-calcite schist derived from sedimentary rocks (Nokleberg and others, 1991). The veins are as much as 24 centimeters thick and contain as much as 71.4 percent antimony (average of 36.5 percent). About half of the stibnite is bladed. A shallow open cut reveals a quartz-stibnite lens a few inches to 12 feet thick. The lens strikes N70W, parallel to the foliation of the schist, but it dips more steeply than the schist (Ebbley and Wright, 1948). The schist is extensively silicified and pyritized near the stibnite-bearing veins. Faulting during or since the formation of the vein is indicated by slickensides and brecciated quartz.
Geologic map unit (-145.854772480703, 63.5080902823659)
Mineral deposit model Simple Sb deposit (Cox and Singer, 1986; model 27d).
Mineral deposit model number 27d
Alteration of deposit The schist is extensively silicified and pyritized near the stibnite-bearing veins. Faulting during or since the formation of the vein is indicated by slickensides and brecciated quartz.

Production and reserves

Workings or exploration The prospect was explored by open cut, stripping, and an adit that is caved at 30 feet (Ebbley and Wright, 1948). The stripped area is about 30 feet north of the open cut, which is 250 feet east of the adit. Assays of the veins showed as much as 71.4 percent antimony; the average is 36.4 percent antimony, but no gold or silver is present.
Indication of production None

References

MRDS Number D001934

References

Reporters W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date 8/9/2002