|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||A-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This prospect is at sea level on the northeast shore of the unnamed cove about 0.3 mile south of Nelson Cove on southwest Gravina Island. The site is in section 15, T. 77 S., R. 88 E., of the Copper River Meridian. It corresponds to loc. 52.1 in Elliott and others (1978). The location is accurate within 0.1 mile.|
Geologic descriptionThe country rocks in the general area of this prospect are complexly folded and faulted Upper Triassic carbonate, clastic, and basaltic volcanic strata (Berg, 1973; Berg and others, 1980). The deposit consists of a 3-foot-wide fault breccia in a mafic dike(?) that is structurally mixed with the Upper Triassic sedimentary and volcanic rocks. The breccia weathers orange or red, and contains quartz, carbonate, barite, and small amounts of unidentified sulfide minerals, which also are sparsely disseminated in the adjacent country rocks. Analyses of samples of the breccia and the adjacent country rocks showed up to 70 ppm Ag, 0.15 ppm Au, more than 0.5% Ba, 700 ppm Cu, 1.5% Pb, and more than 1% Zn (Koch and Elliott, 1978 [OFR 78-156A]). The analytical data indicate that the unidentified sulfide minerals probably include sphalerite, chalcopyrite, and argentiferous galena. In 1969, workings that probably date to the early 1900s consisted of an approximately 21-foot-long adit.
|Geologic map unit||(-131.825676840113, 55.1976523672044)|
|Mineral deposit model||Polymetallic veins? (Singer and Cox, 1986; model 22c)|
|Mineral deposit model number||22c?|
|Age of mineralization||The mineralized fault breccia is Late Triassic or younger.|
|Alteration of deposit||Local iron-staining.|
|Workings or exploration||In 1969, workings that probably date to the early 1900s consisted of an approximately 21-foot-long adit. Analyses of samples of the breccia and the adjacent country rocks showed up to 70 ppm Ag, 0.15 ppm Au, more than 0.5% Ba, 700 ppm Cu, 1.5% Pb, and more than 1% Zn (Koch and Elliott, 1978 [OFR 78-156A]).|
|Indication of production||None|
Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map I-1807, 27 p., scale 1:250,000.
Elliott, R.L., Berg, H.C., and Karl, S.M., 1978, map and table describing metalliferous and selected non-metalliferous mineral deposits, Ketchikan and Prince Rupert quadrangles, Alaska: U.S. Geological Survey Open-File Report 78-73-B, 17 p., 1 sheet, scale 1:250,000.
|Reporters||H.C. Berg, USGS|
|Last report date||7/1/1999|