Unnamed (north of Rua Bay) (ARDF #SR270) Cu

Unnamed (north of Rua Bay)

Occurrence, Inactive

Commodities and mineralogy

Main commodities	Cu
Other commodities	Ag
Ore minerals	chalcopyrite; pyrite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale	SR
Quadrangle map, 1:63,360-scale	B-2
Latitude	60.3646
Longitude	-147.6224
Nearby scientific data	Find additional scientific data near this location
Location and accuracy	The occurrence is located at tidewater 1.3 miles northeast of Rua Cove. It is in the SE1/4 section 12, T. 3 N., R. 10 E., of the Seward Meridian. This is location 212 Tysdal (1978 [MF-880-A]) and location S-68 of Jansons and others (1984). This location is accurate to within a quarter of a mile.

Geologic setting

Geologic description The occurrence is an iron-stained zone near the contact between sheared chloritic greenstone and diorite (Kurtak and Jeske, 1986). The diorite contains 1 to 2 percent disseminated chalcopyrite and pyrrhotite. One sulfide-rich zone averaged 9 inches thick and contained as much as 12 percent total sulfides (Kurtak and Jeske, 1986). Numerous shear zones as much as 18 feet thick cut the diorite and greenstone (Tysdal, 1978 [MF-880-A]). The zones trend northwest and dip nearly vertical (Kurtak and Jeske, 1986). Samples from the occurrence contained from 35 ppm to 0.45 percent copper and from 1.6 to 10 ppm silver (Kurtak and Jeske, 1986).
Geologic map unit	(-147.624351516331, 60.3639617108949)
Mineral deposit model	Cyprus massive sulfide (Cox and Singer, 1986; model 24a)
Mineral deposit model number	24a
Age of mineralization	Tertiary or younger; the mineralization is in rocks of the Orca Group of Tertiary age.
Alteration of deposit	Sheared greenstone is chloritized.

Production and reserves

Workings or exploration	Samples from the occurrence contained from 35 ppm to 0.45 percent copper and from 1.6 to 10 ppm silver (Kurtak and Jeske, 1986).
Indication of production	None

References

References Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, southcentral Alaska: U.S. Bureau of Mines Mineral Land Assessment 5-84, 218 p., 2 sheets, scale 1:250,000. Kurtak, J.M., and Jeske, R.E., 1986, Mineral investigations in the Chugach National Forest, Alaska (Islands area): U.S. Bureau of Mines Open-File Report 54-86, 302 p., 1 sheet, scale 1:63,360. Nelson, S.W., Dumoulin, J. A., and Miller, M.L., 1985, Geologic map of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-B, 16 p., 1 sheet, scale 1:250,000. Tysdal, R.G., 1978, Mines, prospects, and occurrences map of the Seward and Blying Sound quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-880-A, 2 sheets, scale 1:250,000.
Reporters	Jeff A. Huber and Carol S. Huber (Anchorage)
Last report date	12/19/2001