Unnamed (west of Tarr Inlet) (ARDF #MF048) Cu

Unnamed (west of Tarr Inlet)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Au; Co; Ni
Ore minerals	chalcopyrite; pyrite
Gangue minerals	calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale	MF
Quadrangle map, 1:63,360-scale	D-3
Latitude	58.956
Longitude	-136.932
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The occurrence is on the west side of Tarr Inlet, about 0.15 mile west of the shore line and about 2.75 miles north of the mouth of Johns Hopkins Inlet. The elevation is approximately 500 feet. The location is known within about 0.25 mile. The location is same as number 41 of Kimball and others (1978), number 62 of MacKevett and others (1971), and number 13 of Cobb (1972).

Geologic setting

Geologic description The area is mostly underlain by granitic rocks of Cretaceous age (Brew and others, 1978). At the mineral locality, a dike of pegmatitic hornblende diorite 6 feet thick cuts heterogeneous diorite. In turn, the pegmatitic diorite contains quartz-calcite veins as much as 0.5 foot thick that contain pyrite and chalcopyrite. The veins contain as much as 2000 ppm copper, a trace of gold, and 300 ppm each of cobalt and nickel (MacKevett and others, 1971, table 9, location 62).
Geologic map unit	(-136.933883881323, 58.9555959892602)
Mineral deposit model	Lode associated with an intrusive of intermediate to mafic composition.
Age of mineralization	Cretaceous or younger.

Production and reserves

Workings or exploration	Surface exposures only. A grab sample of a quartz-calcite vein in pegmatitic diorite contained 2000 ppm Cu, a trace of gold, and 300 ppm each of cobalt and nickel (MacKevett and others, location 62, table 9).
Indication of production	None
Additional comments The site is in Glacier Bay National Park and Preserve.

References

MRDS Number	A013147
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. Cobb, E.H., 1972, Metallic mineral resources map of the Mount Fairweather quadrangle, AK: U.S. Geological Survey Miscellaneous Field Study Map MF-436, 1 sheet, scale 1:250,000. 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