Asmyrahha Prospect, McGrath District, Yukon-Koyukuk Borough, Alaska, USA
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Location: The Asmyrahha zinc prospect is 1.5 miles (2.4 km) east of Reef Ridge deposit (MD055) at an elevation of approximately 1,500 feet (457 m) in Section 30, T. 24 S., R. 24 E., of the Kateel River Meridian. Location is known to within 125 feet (38 m).
Geology: Smithsonite-bearing rubble is exposed for 150 feet (45 m) of strike length in an old burn area. Host rock for the mineralization is a banded to micritic limestone that is probably equivalent to the Paradise Fork Formation of Dutro and Patton (1982); this is the 'Sic' unit of Andrews and Rishel (1982). The age of the mineralization is unknown. Smithsonite bearing carbonate units strike N 50 E and dip approximately 55 degrees South. Smithsonite mineralization is parallel to the strike of the limestone, but dips 15 degrees South along a low angle structure. Grab samples of the gossan contain up to 8.4 percent zinc with no appreciable lead. A trench cut at right angles to the strike of the ridgeline averaged 0.5 percent zinc and no lead across 10 feet (3 m).
Workings: The Asmyrahha prospect was discovered by WGM Inc. and Patino Ltd. during exploration for base metals in the late 1970s on lands selected by Doyon Ltd. (Andrews and Rishel, 1982). Grab samples of the gossan contain up to 8.4 percent zinc with no appreciable lead. A trench that was cut at right angles to the strike of the ridgeline averaged 0.5 percent zinc and no lead over 10 feet (3 m).
Age: Host rocks are Silurian; age of mineralization is unknown.
Alteration: Ferricrete oxidation at surface.
Commodities (Major) - Zn
Development Status: No
Deposit Model: Southeast Missouri lead-zinc (Cox and Singer, 1986; model no. 32a) or Mississip
2 entries listed. 2 valid minerals.
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Andrews, Tom, and Rishel, John, 1982, Annual Report for 1981, Reef Ridge I-to-XIII Project Areas, Kuskokwim Block, Alaska: Anchorage, Alaska, WGM Inc., Project Report 4, 45 p., 2 sheets, scales 1:63,360 and 1:20,000. (Report held by Doyon, Limited, Fairbanks, Alaska.) Dutro, J.T. Jr., and Patton,W.W. Jr., 1982, New Paleozoic formations in the northern Kuskokwim Mountains, west-central Alaska: U.S. Geological Survey Bulletin 1529-H, p. H13-H22. Patton, W.W. Jr., Moll, E.J., Dutro, J.T., Jr., Silberman, M.L., and Chapman, R.M., 1980, Preliminary geologic map of the Medfra quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-811, one sheet at 1:250,000 scale. Schmidt, J.M., 1997, Shale-hosted Zn-Pb-Ag and barite deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral deposits of Alaska, 1997: Economic Geology Monograph 9, p. 35-65.