|Quadrangle map, 1:250,000-scale||WI|
|Quadrangle map, 1:63,360-scale||B-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is located just east of the ridge line of Midnight Dome at the head of Union Gulch. It is at an elevation of about 3,500 feet, about 0.7 mile southeast of the center of section 35, T. 31 N., R. 12 W. The location is accurate.|
Geologic descriptionThis deposit was described by Ebbley and Wright (1948) as prospect pits that expose a 6-inch quartz vein containing 'kernels' of stibnite in an earthy yellow matrix of antimony oxides. Samples of vein material contained 0.03 to 0.04 parts per million (ppm) gold, up to 0.15 ppm silver, and more than 1 percent antimony. A sample of bedrock contained 0.05 ppm gold, 0.1 ppm silver, and 0.03 percent antimony (Brosge and Reiser, 1970). Samples of a quartz-stibnite vein collected by Dillon (1982) contain up to 14 ppm gold. A sample of fine- to coarse-grained, crystalline stibnite from dump material assayed 62 percent antimony (Mulligan, 1974). The prospect was examined and sampled by Kurtak and others (2002). They found two trenches about 12 feet long. They analyzed a select sample that contained 33.13 percent antimony and 14 parts per billion gold. About a quarter of a mile south of this prospect, they collected two samples of quartz veins that cut chlorite schist. They averaged 321 ppb gold, 373 ppm lead, 365 ppm arsenic, and 317 ppm antimony. (This occurrence to the south is not the occurrence just west of hill 3860 (WI132) that they describe separately.) The rocks in the area are Middle or Upper Devonian(?) calcareous, chloritic wacke (Dillon and others, 1986).
|Geologic map unit||(-150.150047546941, 67.4618746318149)|
|Mineral deposit model||Simple stibnite deposit (Cox and Singer, 1986; model 27d).|
|Mineral deposit model number||27d|
|Age of mineralization||Devonian or younger based on the age of the host rocks.|
|Alteration of deposit||Oxidation of stibnite to yellow antimony oxides.|
|Workings or exploration||There are at least two prospect pits and the prospect has been sampled repeatedly by government agencies.|
|Indication of production||None|
Additional commentsSee also: Jones and Boyle (WI114), and Wannemaker and Wortman (WI115).
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Chandalar and Wiseman quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-340, 205 p.
Dillon, J.T., 1982, Source of lode and placer gold deposits of the Chandalar and upper Koyukuk Districts: Alaska Division of Geological and Geophysical Surveys Open-File Report AOF-158, 25 p., 1 sheet, scale 1:250,000.
Ebbley, Norman, Jr., and Wright, W.S., 1948, Antimony deposits in Alaska: U.S. Bureau of Mines Report of Investigations 4173, 41 p.
Eden, K., 2000, Geology and gold mineralization of the Nolan area in the Brooks Range, Alaska: U.S. Bureau of Land Management Open-File Report 78, 87 p.
Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Maclean, E.A., 2002, Mineral investigations in the Koyukuk mining district, northern Alaska: Final Report: U.S. Bureau of Land Management Technical Report 50, v. 1 and 2, 845 p.
Kurtak, J.M., Klieforth, R.F., Clark, J.M., and Williams, E.M., 1999, Mineral investigations in the Koyukuk mining district, northern Alaska--Progress Report: U.S. Bureau of Land Management Open-File Report 74, 158 p.
|Reporters||J.M. Britton (Anchorage); D.J. Grybeck (Contractor, USGS)|
|Last report date||2/1/2011|