Unnamed (south of Black Rapids Roadhouse) (ARDF #MH014) Sb

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 Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p. Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p. Ebbley, Norman, Jr., and Wright, W.S., 1948, Antimony deposits in Alaska: U.S. Bureau of Mines Report of Investigations 4173, 41 p. MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000. Moffit, F.H., 1954, Geology of the eastern part of the Alaska Range and adjacent area: U.S. Geological Survey Bulletin 989-D, p. 65-218. Mulligan, J.J., 1974, Mineral resources of the Trans-Alaska Pipeline corridor: U.S. Bureau of Mines Information Circular 8626, 24 p., 9 sheets, scale 1:250,000. Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
Reporters	W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date	8/9/2002