Wyrick Prospect, Iditarod District, Yukon-Koyukuk Borough, Alaska, USA
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Geology: The Wyrick prospect consists of quartz-stibnite gash veins that cut shale and sandstone of the Upper Cretaceous, Kuskokwim Group and an Upper Cretaceous granite-porphyry dike (Bundtzen, Miller, and Laird, 1986; Miller and Bundtzen, 1994). Five individual gash veins of quartz that contain stibnite, pyrite, and the secondary antimony minerals kermesite and stibiconite are found in shear zones and along the sides of the granite-porphyry dikes. The veins strike N85E and dip steeply to vertically. Most of the veins are from 1 to 12 inches thick but one mineralized shear zone is about 20 feet thick. This zone can be traced along strike for about 65 feet where is covered by soil and vegetation. Stibnite occurs as radiating crystals up to 3 inches long and an inch wide. Chip-channel samples of the mineralized zone contained from 0.55 to 30.9 percent antimony, up to 700 parts per billion (ppb) gold, and 4,000 ppb silver. Detailed sampling indicates that the large shear zone contains 2.4 to 3.1 tons of antimony per vertical foot (Bundtzen, Miller, and Laird, 1986).
Workings: The Wyrick Lode was discovered in 1984 when L.E. Wyrick was digging a bedrock drain for his placer mine. Another bedrock drain about 50 feet east exposed an extension of the mineralization. Battle Mountain Mining Company explored the property in the late 1980s, and drilled one diamond core hole (Szumigala, 1993). Results of that investigation are confidential. Paul Glavinovich and William Morgan completed an investigation of the Wyrick prospect and surrounding area in 1994 (Glavinovich and Morgan, 1994). From 1996-1997, Placer Dome Exploration flew an aeromagnetic survey over the Upper Granite Creek area, including the Wyrick Lode area. Results of that survey have not been publicly released (L.E. Wyrick, oral communication, 2003).
Age: Unknown; a nearby intrusion has a 40K/40Ar age of 71.1 Ma (Miller and Bundtzen, 1994).
Alteration: Yellow-brown unidentified clay alteration.
Reserves: Detailed sampling indicates that the large shear zone contains 2.4 to 3.1 tons of antimony per vertical foot (Bundtzen, Miller, and Laird, 1986).
Commodities (Major) - Au, Sb; (Minor) - Ag, Hg, Pb
Development Status: None
Deposit Model: Simple Sb veins (Cox and Singer, 1986; model 27d).
Mineral List
5 entries listed. 4 valid minerals.
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References
Bundtzen, T.K., Cox, B.C., and Veach, N.C., 1987, Heavy mineral provenance studies in the Iditarod and Innoko districts, western Alaska: Process Mineralogy VII, The Metallurgical Society, p. 221-246. Bundtzen, T.K., Miller, M.L., and Laird, G.M., 1986, Prospect examination of the Wyrick placer/lode system, Granite Creek, Iditarod-George mining district, Iditarod B-2 quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Public Data File Report 86-29, 10 p., 1 sheet, scale 1:200. Miller, M.L., and Bundtzen, T.K., 1994, Generalized geologic map of the Iditarod quadrangle, Alaska showing potassium-argon, major oxide, trace element, fossil, paleocurrent, and archeological sample localities: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-A, 48 pages; 1 sheet, scale 1:250,000. Miller, M.L., Bundtzen, T.K., and Gray, J.E., 2005, Mineral resource assessment of the Iditarod quadrangle, west-central Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2219-B, scale 1:250,000, pamphlet.