|Quadrangle map, 1:250,000-scale||SM|
|Quadrangle map, 1:63,360-scale||D-4|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Willis Mine is on a knob east of the east branch of Willis Creek, about 1.4 mile northwest of the mouth of Parks Creek. It is at an elevation of about 700 feet in the NW1/4 sec. 24, T. 20 N., R. 45 W., of the Seward Meridian. The mine is locality 9 of Miller and others (1989). The location is accurate.|
The Willis deposit is in sandstone, siltstone, and shale of the Upper Cretaceous,s Kuskokwim Group and in altered mafic dikes (Cady and others, 1955; Sainsbury and MacKevett, 1965). The deposit consists of quartz veins that contain cinnabar, stibnite, pyrite, hematite, and minor stibiconite. The veins are up to 50 feet long and 6 inches thick; they fill fractures in or near mafic dikes and sills that are largely altered to silica, carbonate minerals, and dickite. The veins strike N30-65W and dip steeply either NE or SW (Sainsbury and MacKevett, 1965). The cinnabar grains, which are zoned, are brilliant red or dark purple and iron-enriched (Sainsbury and MacKevett, 1965).
The ore bodies are localized near the intersections of altered gently-dipping dikes and sills with bedding plane faults that cut the Kuskokwim Group. The quartz-cinnabar-stibnite veins appear to parallel the strike of the shallow- dipping dikes and sills, a structural setting that differs somewhat from that at the Red Devil Mine (SM028). The mineralization is in a broad northwest-trending zone parallel to the axis of the Sleetmute anticline (Cady and others, 1955).The property was first staked in 1909 by Oswald Willis and Jack Fuller, who retorted a few flasks of mercury from 1914 to 1918 (Cady and others, 1955).
|Geologic map unit||(-157.366131454006, 61.815060090206)|
|Mineral deposit model||Silica-carbonate mercury (Cox and Singer, 1986; model 27c).|
|Mineral deposit model number||27c|
|Age of mineralization||Undated; the nearby Fairview prospect (ARDF SM019) has a 40Ar/39Ar age of 72.6 Ma (Gray, Gent, and others, 1997).|
|Alteration of deposit||Mafic dikes and sills are are largely altered to silica, carbonate minerals, and dickite.|
|Workings or exploration||The property was staked by Oswald Willis and Jack Fuller; in 1943, it was conveyed to Oswald's nephew George Willis. The U.S. Bureau of Mines trenched the property in 1943 (Webber and others, 1947). Development work was limited to trenches, pits and several short adits into mineralized outcrops (Jasper, 1955, [PE 82-3]), 1961; Sainsbury and MacKevett, 1965; Miller and others, 1989). After George Willis trenched the property in 1953 and 1954, Jasper (1961) suggested that the Willis prospect could be a large, low grade, bulk-mineable mercury deposit. Alaska Mines and Minerals Inc. optioned the property in 1957.|
|Indication of production||Yes; small|
|Production notes||Oswald Willis and Jack Fuller retorted ore and produced a few flasks of mercury from 1914 to 1918 (Cady and others, 1955).|
Cady, W.M., Wallace, R.E., Hoare, J.M., and Webber, E.J., 1955, The central Kuskokwim region, Alaska: U.S. Geological Survey Professional Paper 268, 132 p.
Cobb, E.H., 1972, Metallic mineral resources map of the Sleetmute quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-368, 1 sheet, scale 1:250,000.
Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Dillingham, Sleetmute, and Taylor Mountains quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.
Gray, J.E., Gent, C.A., Snee, L.W., and Wilson, F.H., 1997, Epithermal mercury-antimony and gold-bearing vein lodes of southwest Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 287-305.
Jasper, Martin, 1955, Willis cinnabar property: Alaska Territorial Department of Mines Property Examination Report PE 82-3, 19 p.
Jasper, Martin, 1961, Cinnabar province, Kuskokwim region, in Williams, J.A., Report of the Alaska Division of Mines and Minerals Report for the Year 1961: Alaska Division of Mines and Minerals Annual Report, p. 65-79.
MacKevett, E.M., Jr., and Berg, H.C., 1963, Geology of the Red Devil quicksilver mine, Alaska: U.S. Geological Survey Bulletin 1142-G, p. G1-G16.
Miller, M.L., Belkin, H.E., Blodgett, R.B., Bundtzen, T.K., Cady, J.W., Goldfarb, R.J., Gray, J.E., McGimsey, R.G., and Simpson, S.L., 1989, Pre-field study and mineral resource assessment of the Sleetmute quadrangle, southwestern Alaska: U.S. Geological Survey Open-File Report 89-363, 115 p., 3 plates, scale 1:250,000.
Roedder, E., 1972, Compositions of fluid inclusions: U.S. Geological Survey Professional Paper 440-JJ, 164 p.
Sainsbury, C.L., and MacKevett, E.M., Jr., 1965, Quicksilver deposits of southwestern Alaska a description of the quicksilver mines and prospects, with special emphasis on the structural controls of ore deposition: U.S. Geological Survey Bulletin 1187, 89 p.
Webber, B.S., Bjorklund, S.C., Rutledge, F.A., Thomas, B.I., and Wright, W.S., 1947, Mercury deposits of southwestern Alaska: U.S. Bureau of Mines Report of Investigations 4065, 57 p.
Wells, J.T., and Ghiorso, M.S., 1988, Rock alteration, mercury transport, and metal deposition at Sulphur Bank, California: Economic Geology, vol. 83, p. 606-618.
White, D. E., and Robinson, C. E., 1962, Sulphur Bank, California, a major hot spring quicksilver deposit, in Engel, A.E.J., James, H.L., and Leonard, B.F., eds., Petrologic studies: A volume in honor of A.F. Buddington: Boulder, Colorado, Geological Society of America p. 397-428.
|Reporters||T.K. Bundtzen (Pacific Rim Geological Consulting, Inc.) and M.L. Miller (U.S. Geological Survey)|
|Last report date||5/3/2003|