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Unnamed (west of upper Cross Creek)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Au; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; gold; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale NB
Quadrangle map, 1:63,360-scale A-4
Latitude 62.0706
Longitude -142.582
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is in a small unnamed drainage on the northwest side of the valley of Cross Creek . It is at an elevation of about 6,200 feet, 1,500 feet southeast of elevation 7115, and 4,500 feet west of Cross Creek. The occurrence is about 0.1 mile northeast of the center of section 1, T. 3 N., R. 15 E. of the Copper River Meridian. This is locality 17 of Richter (1973), locality 35 of Richter and others (1975), and National Park Service locality WRST-50 (unpublished data). Cobb and Richter (1980 [OFR 80-927]) included this locality as an 'Unnamed occurrence'. It is located to within a few hundred feet.

Geologic setting

Geologic description

This occurrence is a quartz vein that contains minor pyrite, chalcopyrite, galena, and sphalerite; it cuts hornfelsed volcanic country rock that has disseminated galena and sphalerite (Richter and Matson, 1970 [OFR 70-276]; Richter and others, 1975). A sample of a 20-foot-long quartz vein contained 0.8 parts per million (ppm) gold and a sample of volcanic hornfels with disseminated galena and sphalerite contained 0.9 ppm gold, 300 ppm copper, 3,000 ppm lead, and more than 10,000 ppm zinc (Richter and Matson, 1970 [OFR 70-276]). The volcanic host rocks are part of the upper Paleozoic, Tetelna Volcanics that form a roof pendant over a Tertiary porphyry complex (Richter, 1973, Richter, 1976).
Geologic map unit (-142.584128924555, 62.0702072322012)
Mineral deposit model Polymetallic veins (Cox and Singer, 1986; model 22c)
Mineral deposit model number 22c
Age of mineralization Tertiary? Mineralization is in a large metavolcanic roof pendant in a Tertiary porphyry complex (Richter, 1973; 1976).

Production and reserves

Workings or exploration Probably only surface examination.
Indication of production None

Additional comments

The occurrence is in the Wrangell-St. Elias National Preserve.

References

MRDS Number A011408

References

Cobb, E.H., and Richter, D.H., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Nabesna quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-927, 117 p.
Richter, D.H., 1976, Geologic map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-932, 1 sheet, scale 1:250,000.
Richter, D.H., and Matson, N.A., Jr., 1970, Geochemical data from the Nabesna A-4 quadrangle, Alaska: U.S. Geological Survey Open-File Report 70-276, 14 p., 1 sheet, scale 1:63,360.
Richter, D.H., Singer, D.A., and Cox, D.P., 1975, Mineral resources map of the Nabesna quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-655-K, 1 sheet, scale 1:250,000.
Reporters Travis L. Hudson (Applied Geology)
Last report date 11/24/2002