|Quadrangle map, 1:250,000-scale||CV|
|Quadrangle map, 1:63,360-scale||C-3|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This occurrence is at an elevation of about 2200 feet on the north wall of Grinnell Glacier. It is in SE1/4 sec. 24, T. 13 S., R. 3 E., of the Copper River Meridian. Site is accurately located to within 1000 ft. This location is site C-11 of Jansons and others (1984).|
This occurrence consists of sulfide-bearing shear zones 2 to 10 feet wide in slate and greenstone of the Upper Cretaceous Valdez Group (Nelson and others, 1985). Ore minerals include arsenopyrite, chalcopyrite, malachite, pyrite, and pyrrhotite. Four chip samples collected and analyzed by the U.S. Bureau of Mines contained 255 ppm to 0.13% Cu; nine grab samples contained 13 ppm to 0.19% Cu (Jansons and others, 1984). This site is at the eastern end of a 65-mile-long belt of similar rocks that to the west host massive sulfide deposits (Nelson and others, 1984; 1985; Crowe and others, 1992).A massive-sulfide boulder found on the south side of Grinnel Glacier contained 30% pyrite, 3% chalcopyrite, 1% sphalerite in a quartz-sericite gangue (Kodosky and Teller, 1989). Assays of selected samples ranged from 1100 ppm to 1.8% Cu.
|Geologic map unit||(-144.782997765789, 60.7264847647281)|
|Mineral deposit model||Besshi massive sulfide (Cox and Singer, 1986; model 24b)|
|Mineral deposit model number||24b|
|Age of mineralization||Late Cretaceous based on the age of the host rocks.|
|Alteration of deposit||Local alteration of copper minerals.|
|Workings or exploration||
Site examined during U.S. Bureau of Mines and U.S.G.S. mineral resource assessment of the Chugach National Forest (Jansons and others, 1984; Nelson and others, 1984). Site also examined in 1988 by Kodosky and Teller (1989) for the Chugach Alaska Corporation. Their evaluation indicated some potential for copper mineralization.Four chip samples collected and analyzed by the U.S. Bureau of Mines contained 255 ppm to 0.13% Cu; nine grab samples contained 13 ppm to 0.19% Cu (Jansons and others, 1984). A massive-sulfide boulder found on the south side of Grinnel Glacier contained 30% pyrite, 3% chalcopyrite, 1% sphalerite in a quartz-sericite gangue. Assays of selected samples ranged from 1100 ppm to 1.8% Cu.
|Indication of production||None|
Additional commentsChugach Alaska Corporation, Anchorage, Alaska has control of these lands.
Crowe, D.E., Nelson, S.W., Brown, P.E., Valley, J.W., and Shanks, W.C., III, 1992, Geology and geochemistry of volcanogenic massive sulfide deposits and related igneous rocks, Prince William Sound region, south-central Alaska: Economic Geology, v. 87, no. 7, p. 1722-1746.
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.
Kodosky, Larry, and Teller, Steve, 1989, Economic mineral assessment of Chugach Alaska Corporation properties and selected land in the Copper, Bremner, and Tasnuna River area: Unpublished report prepared for Chugach Alaska Corporation, Anchorage, Alaska, 116 p.
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.
Nelson, S.W., Miller, M.L., Barnes, D.F., Dumoulin, J.A., Goldfarb, R.J., Koski, R.A., Mull, C.G., Pickthorn, W.J., Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral resource potential of the Chugach National Forest, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1645-A, 24 p., 1 plate, scale 1:250,000.
|Reporters||S.W. Nelson, Anchorage, AK|
|Last report date||6/10/2000|