|Quadrangle map, 1:250,000-scale||MH|
|Quadrangle map, 1:63,360-scale||A-1|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The occurrence is on the west side of the Slana River about 3.7 miles west-northwest of Gillett Pass at an elevation of 4,200 feet. The occurrence is about 0.3 mile east of the center of section 13, T. 15 N., R. 5 E., Copper River Meridian. The occurrence corresponds to locality 5 of Richter (1967), locality 4 of Richter and others (1977), locality 31 on figure 5 of Cobb (1979 [OFR 79-238]), and locality 143 in table 2 of Nokleberg and others (1991).|
The rocks at this occurrence are Nikolai Greenstone of Middle or Late Triassic age (Richter and others, 1977). The rocks were previously mapped as Slana basalt (Richter (1967). The basalt is amygdaloidal and pervasively altered; phenocrysts of plagioclase, pyroxene, and olivine are altered and occur in a groundmass that has been largely altered to chlorite, epidote, and serpentinite. Minerals contained in amygdules include quartz, potassium feldspar, calcite, chlorite, epidote, pumpellyite, prehnite, and zeolite minerals (Richter and others, 1977).
The mineralized area is about one-half mile south of the Denali Fault and is cut by subsidiary faults subparallel to it (Richter and others, 1967). The occurrence consists of pyrrhotite with lesser chalcopyrite in a lenticular mass about 10 feet thick and 100 to 150 feet long enclosed in the altered basalt. The topography is very steep, and only float material was sampled. A sample of pyrrhotite-rich float contained 0.6 percent copper, 0.04 percent nickel, 0.02 ounce of gold per ton, and a trace of silver (Richter, 1967).A stream-sediment sample collected in the gulch below the deposit contained 340 parts per million (ppm) copper, 60 ppm lead, and more than 1,000 ppm arsenic (Richter, 1967).
|Geologic map unit||(-144.372930992222, 63.0810117051208)|
|Mineral deposit model||Basaltic Cu (Cox and Singer, 1986; model 23).|
|Mineral deposit model number||23|
|Age of mineralization||Late Triassic or younger, on the basis of the age of host rock.|
|Alteration of deposit||Pervasive propylitic alteration of basalt.|
|Workings or exploration||The massive sulfide lens is exposed on a very steep slope and has not been mapped or sampled in detail.|
|Indication of production||None|
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Mount Hayes quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-238, 140 p.
MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.
Nokleberg, W.J., Lange, I.M., Roback, R.C., Yeend, Warren, and Silva, S.R., 1991, Map showing locations of metalliferous lode and placer mineral occurrences, mineral deposits, prospects, and mines, Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-1996-C, 42 p., 1 sheet, scale 1:250,000.
Richter, D.H., 1967, Geology of the upper Slana-Mentasta Pass area, southcentral Alaska: Alaska Division of Mines and Minerals Geologic Report 30, 30 p., 2 sheets, scale 1:63,360.
|Reporters||W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group), and W.J. Nokleberg (USGS)|
|Last report date||7/14/2003|