|Quadrangle map, 1:250,000-scale||CV|
|Quadrangle map, 1:63,360-scale||B-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||This location includes the McKinley Lake mine, the Rilley Group prospect , the Lucky Strike prospect , and the Bear Creek prospect. The map site is the center of an approximately 0.75 square mile area north of McKinley Lake that contains these mines and prospects. It is in S1/2 sec. 15, T. 16 S., R. 1 E., of the Copper River Meridian. Accuracy of location is within 400 ft. The site corresponds to localities C-6 to C-9 in Jansons and others (1984), and locality 29 in Cobb (1972: MF-392).|
Geologic descriptionThe deposits at this site consist of reportedly auriferous quartz veins in Tertiary Orca Group sedimentary rocks adjacent to the 51.6 Ma McKinley Lake pluton (Winkler and Plafker, 1981). Schrader and Spencer (1901) report that the veins both parallel and cross-cut the bedding in the host rock. They also report large amounts of visible gold in the quartz. Haney and Jansons (1987) report three major quartz veins and quartz stockworks from a few inches up to 40 ft. thick. They note that the veins are parallel to bedding in the host rock. Minerals noted by them include pyrite, stibnite, and gold. Analyses of samples from two adits at McKinley Lake contained 0.005 to 0.107 oz. Au/ton and 0.2 oz. Ag/ton. Samples from the mill site contained 25-50 ppm Au and 2.6 ppm Ag (Jansons and others, 1984). Goldfarb and others (1992) report anomalous values of Ag, As, and Au in concentrate samples from streams draining the nearby granite stock. They consider the granite to be the heat source for the mineralizing event.
|Geologic map unit||(-145.194996502523, 60.4801715230953)|
|Mineral deposit model||Chugach-type low sulfide Au-quartz veins (Bliss, 1992; Goldfarb and others, 1986)|
|Age of mineralization||Tertiary (51 Ma) based on the age of the mineralizing event (Goldfarb and others, 1992).|
|Workings or exploration||
Five adits ranging from 18-569 ft.; one shaft and numerous open cuts. Ball mill on site.Analyses of samples from two adits at McKinley Lake contained 0.005 to 0.107 oz. Au/ton and 0.2 oz. Ag/ton. Samples from the mill site contained 25-50 ppm Au and 2.6 ppm Ag (Jansons and others, 1984). Goldfarb and others (1992) report anomalous values of Ag, As, and Au in concentrate samples from streams draining the nearby granite stock.
|Indication of production||Yes; small|
|Production notes||16 oz. Au and 9 oz. Ag apparently produced in the early 1900s (Schrader and Spencer, 1901).|
Additional commentsSite is in Chugach National Forest.
Bliss, J.D., 1992, Grade and tonnage model of Chugach-type low-sulfide Au-quartz veins: U.S. Geological Survey Bulletin 2004, p. 44-46.
Cobb, E.H., 1972, Metallic mineral resources map of the Cordova quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-392, 1 sheet, scale 1:250,000.
Goldfarb, R.J., Case, J.E., Plafker, George, and Winkler, G.R., 1992, Maps showing areas of potential for mineral resources in the Cordova and northern Middleton Island 1-degree x 3-degree quadrangles, southern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2190, 1 sheet, scale 1:250,000.
Goldfarb, R.J., Leach, D.L., Miller, M.L., and Pickthorn, W.J., 1986, Geology, metamorphic setting, and genetic constraints of epigenetic lode-gold mineralization within the Cretaceous Valdez Group, south-central Alaska, in Keppie, J.D., Boyle, R.W., and Haynes, S.J., eds., Turbidite-hosted gold deposits: Geological Association of Canada Special Paper 32, p. 87-105.
Haney, J.M., and Jansons, Uldis, 1987, Geology of the McKinley Lake gold area, Chugach National Forest, south-central Alaska: U.S. Bureau of Mines Open-File Report 32-87, 40 p., 1 sheet.
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.
Schrader, F.C., and Spencer, A.C., 1901, The geology and mineral resources of a portion of the Copper River District, Alaska: U.S. Geological Survey, 100 p., 5 sheets.
|Reporters||S.W. Nelson, Anchorage, AK|
|Last report date||6/10/2000|