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Unnamed (west of Tarr Inlet)

Occurrence, Inactive

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Commodities and mineralogy

Main commodities Cu
Other commodities Ag; Zn
Ore minerals chalcopyrite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale MF
Quadrangle map, 1:63,360-scale D-3
Latitude 58.98
Longitude -137
Nearby scientific data Find additional scientific data near this location
Location and accuracy The occurrence is at an elevation of 1700-1800 feet about 0.75 miles southwest of the shore of Tarr Inlet and about 5 miles northwest from the mouth of the inlet. It is in the NE 1/4 SW 1/4, section 28, T. 33 S., R. 51 E., of the Copper River Meridian. The occurrence is the same as number 63 of MacKevett and others (1971, table 9), and is probably in the same general area as number 26 of Kimball and others (1978), which is in the adjacent Mt. Fairweather D-4 quadrangle. The location is probably accurate within a radius of 0.25 mile.

Geologic setting

Geologic description

The country rocks in the area of this occurrence consist of a granitic batholith of Cretaceous age that intrudes volcanic and volcaniclastic strata of Permian age, and an intermediate area of mixed granitic and metamorphic rocks (Brew and others, 1978).
The mineral occurrence consists of quartz monzonite that is cut by veins and veinlets of quartz which contain pyrite and chalcopyrite. MacKevett and others (1971) reported a grab sample of sericitically altered quartz monzonite contained 1000 ppm copper, 300 ppm zinc, and 1 ppm silver. The ore mineralogy, alteration, and geologic setting suggest that the occurrence is part of a porphyry copper deposit.
Geologic map unit (-137.001890946743, 58.9795933158532)
Mineral deposit model Porphyry copper (Cox and Singer, 1986; model 17).
Mineral deposit model number 17
Age of mineralization Cretaceous or younger, related to quartz monzonite intrusions.
Alteration of deposit Greenish, sericitic alteration reported by MacKevett and others, (1971, table 9).

Production and reserves

Workings or exploration Surface exposure; one sample (Hx-391, table 9, MacKevett and others, 1971) contained 1000 ppm copper, 1 ppm silver , and 300 ppm zinc).
Indication of production None

Additional comments

The occurrence is in Glacier Bay National Park and Preserve.

References

MRDS Number A013145

References

Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p., 7 sheets.
Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.
MacKevett, E.M., Jr., Brew, D.A., Hawley, C.C., Huff, L.C., and Smith, J.G., 1971, Mineral resources of Glacier Bay National Monument, Alaska: U.S. Geological Survey Professional Paper 632, 90 p., 12 plates, scale 1:250,000.
Reporters C.C. Hawley (Hawley Resource Group)
Last report date 4/9/1999