3-J (ARDF #SI055) Cu, Mo

3-J

Prospects, Probably inactive

Alternative names

Three J
3 J

Commodities and mineralogy

Main commodities	Cu; Mo
Ore minerals	chalcopyrite; molybdenite

Geographic location

Quadrangle map, 1:250,000-scale	SI
Quadrangle map, 1:63,360-scale	D-4
Latitude	57.7868
Longitude	-135.0461
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	According to the U.S. Bureau of Land Management (2002), the 3-J prospect (MAS no. 0021140211) is at an elevation of about 150 feet, about 0.4 mile north of Coffee Cove in Tenakee Inlet, and the Three J prospect (MAS no. 0021140102) is at sea level at the northeast corner of an unnamed cove about 0.5 mile west of Coffee Cove. The prospects are about 0.4 mile apart. Bittenbender and others' location P-26 (1999) coincides with the Bureau's 3-J prospect, and Cobb's location 47 (1972, 1978) coincides with the Bureau's Three J prospect. For this record, the site is plotted at Cobb's location 47 ( which he calls the 3 J (no hyphen)) prospect, at the northeast corner of the unnamed cove. The location is accurate.

Geologic setting

Geologic description Several prospect are in a stock of Cretaceous granodiorite (Lathram and others, 1965). Smith (1942) reports aplite(?) dikes up to 20 feet thick that cut the granodiorite. Chalcopyrite and molybdenite occur in in the dikes and in the granodiorite, but more chalcopyrite is in the granodiorite and more molybdenite is in the aplite. A chip sample of the dike contained 0.1 percent copper and 0.7 percent molybdenum; a chip sample of the granodiorite contained less than 0.01 percent copper and molybdenum. Bittenbender and others (1999) collected several samples; a 0.3-foot sample contained 0.3 percent copper and 0.02 percent molybdenum. At least one claim was staked in 1941.
Geologic map unit	(-135.047877356394, 57.7864605262841)
Mineral deposit model	Porphyry molybdenum-copper deposit.
Age of mineralization	Cretaceous or younger based on the age of the host rock.

Production and reserves

Workings or exploration	At least one claim as staked in 1941; some surface sampling since by government geologists.
Indication of production	None

References

MRDS Number	A013294
References Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p. Bittenbender, P., Still, J.C., Maas, K., and McDonald, M., Jr., 1999, Mineral resources of the Chichagof and Baranof Islands area, southeast Alaska: Bureau of Land Management, BLM-Alaska Technical Report 19, 222 p. Cobb, E.H., 1972, Metallic mineral resources map of the Sitka quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-467, scale 1:250,000. Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Sitka quadrangle: U.S. Geological Survey Open-File Report 78-450, 124 p. Eakins, G.R., 1975, Uranium investigations in southeastern Alaska: Alaska Division of Geological and Geophysical Surveys Geologic Report 44, 62 p. Lathram, E.H., Pomeroy, J.S., Berg, H.C., and Loney, R.A., 1965, Reconnaissance geology of Admiralty Island, Alaska: U.S. Geological Survey Bulletin 1181-R, p. R1-R48. Smith, P.S., 1942, Occurrences of molybdenum in Alaska: U.S. Geological Survey Bulletin 926-C, p. 161-210. U.S. Bureau of Land Management, 2002, Alaska mineral locations database report (Sitka quadrangle), July 2, 2002, 205 p. [http://imcg.wr.usgs.gov/dem.html]
Reporters	Donald Grybeck (U.S. Geological Survey)
Last report date	5/5/2005