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Unnamed (upper Black River)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu; Mo
Other commodities Au; W
Ore minerals chalcopyrite; molybdenite

Geographic location

Quadrangle map, 1:250,000-scale TK
Quadrangle map, 1:63,360-scale B-3
Latitude 62.272
Longitude -148.0925
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 5,350 feet on the east, valley wall at the head of Black River, about a mile to the east of a large, unnamed glacier. It is about 0.5 mile northeast of the center of sec. 11, T. 25 N., R. 7 E., Seward Meridian. The location is accurate to within 1/2 mile.

Geologic setting

Geologic description

This occurrence consists of chalcopyrite- and molybdenite-bearing granitic and andesitic float. It is in an area underlain by Jurassic granodiorite cut by northeast-trending shear zones and intruded by andesite(?) dikes (Csejtey and others, 1978). Samples of mineralized float contain up to 0.15 part per million gold, 446 parts per million molybdenum, 180 parts per million tungsten, and 0.69 percent copper (Kurtak and others, 1992). Placer samples are locally anomalous in gold, lead, tungsten, and zinc (Kurtak and others, 1992).
Geologic map unit (-148.094702327224, 62.2715130424646)
Mineral deposit model Porphyry Cu-Au or Porphyry Cu-Mo? (Cox and Singer, 1986; model 20c or 21a?)
Mineral deposit model number 20c or 21a?
Alteration of deposit Altered granitic rocks are limonite-stained near altered andesitic dikes. The andesite locally is copper stained (Kurtak and others, 1992).

Production and reserves

Workings or exploration Limited sampling by the U.S. Bureau of Mines (Kurtak and others, 1992).
Indication of production None

Additional comments

MAS/MILS number 20760098.

References

MRDS Number A106297

References

Csejtey, Bela, Jr., Nelson, W.H., Jones, D.L., Silberling, N.J., Dean, R.M., Morris, M.S., Lanphere, M.A., Smith, J.G., and Silberman, M.L, 1978, Reconnaissance geologic map and geochronology, Talkeetna Mountains quadrangle, northern part of Anchorage quadrangle, and southwest part of Healy quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-558-A, 60 p., 1 sheet, scale 1:250,000.
Kurtak, J.M., Southworth, D.D., Balen, M.D., and Clautice, K.H., 1991, Mineral investigations in the Valdez Creek Mining District, south-central Alaska: U.S. Bureau of Mines Open-File Report 1-92, 658 p., 2 sheets, scale 1:250,000.
Reporters R.K. Rogers (U. S. Geological Survey contractor)
Last report date 10/2/2002