Lamb claims (Nos. 1-6) (ARDF #MH027) Cu

Lamb claims (Nos. 1-6)

Occurrence, Inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale	MH
Quadrangle map, 1:63,360-scale	B-6
Latitude	63.3621
Longitude	-146.8334
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The Lamb claims occurrence is on a steep slope between 5,500 and 6,000 feet elevation. It is about one-quarter mile north-northwest of peak 6440 in the NW1/4NW1/4 section 17, T. 18 S., R. 5 E., Fairbanks Meridian. The occurrence corresponds to locality 14 of Cobb (1979 [OFR 79-238]) and to a malachite location reported by Smith and others (1975). It also corresponds to locality A3 of Kurtak and others (1992). The location is probably accurate within one-quarter mile.

Geologic setting

Geologic description Rock at the occurrence consists mainly of pegmatite and amphibolite gneiss (Nokleberg and others, 1981). Chalcopyrite, molybdenite, and possibly an unidentified tungsten mineral are sparsely disseminated in the pegmatite and gneiss. Malachite is locally abundant as fracture coatings on weathered amphibolite (Smith and others, 1975; Cobb, 1979 [OFR 79-238]). The rocks are locally iron stained from oxidation of sulfides or possibly biotite. The locality was sampled by the U.S. Bureau of Mines (Kurtak and others, 1992). Sample 1682 of biotite gneiss containing disseminated chalcopyrite assayed 0.5 percent copper and contained slightly anomalous amounts of gold (145 parts per billion) and silver (2.5 parts per million [ppm]); it also contained 170 ppm tungsten. A molybdenite-bearing granite gneiss (sample 618) contained 0.17 percent molybdenum. Intrusion of the pegmatite, regional metamorphism of amphibolite, and introduction of metallic minerals probably occurred in the Late Cretaceous or early Tertiary (Nokleberg and others, 1981).
Geologic map unit	(-146.835672715703, 63.3616619386778)
Mineral deposit model	Porphyry Cu-Mo (Cox and Singer, 1986; model 21a).
Mineral deposit model number	21a
Age of mineralization	Probably Late Cretaceous or Early Tertiary, the age of intrusion and metamorphism of the Maclaren complex (Nokleberg and others, 1981).

Production and reserves

Workings or exploration	The area has been mapped and sampled, but there are no substantial physical workings.
Indication of production	None

References

References Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p. 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. Nokleberg, W.J., Zehner, R.E., Lange, I.M., and Tripp, R.B., 1981, Metallogeny of accreted Andean-type arc and island arc terranes, Mount Hayes quadrangle, eastern Alaska Range, Alaska [abs.]: Geological Association of Canada Abstracts, v. 6, p. A-43. Smith, T.E., Kline, J.T., and Coursey, N.D., 1975, Analyses of stream-sediment samples, Mt. Hayes B-6 Quadrangle, south-central Alaska: Alaska Division of Geological & Geophysical Surveys Alaska Open-File Report 70, 2 p., 2 sheets, scale 1:63,360.
Reporters	W.T. Ellis (Alaska Earth Science), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)
Last report date	7/30/2001