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Crystal Gulch

Mine, Inactive

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Commodities and mineralogy

Main commodities Ag; Au
Other commodities Bi; Sn; U
Ore minerals bismuth; brookite; cassiterite; gold
Gangue minerals very abundant magnetite

Geographic location

Quadrangle map, 1:250,000-scale MD
Quadrangle map, 1:63,360-scale A-4
Latitude 63.234
Longitude -154.78
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Crystal Gulch placer deposit is in a steep, southerly-facing, first order gulch located at 900 feet (274 m) in Section 13, T. 26 S., R. 21 E., of the Kateel River Meridian. Location is accurate to within 100 feet (30 m).

Geologic setting

Geologic description

The rich Crystal Gulch placer deposit occurs in a steep first order tributary of Ruby Creek. Stream gradient averages about 500 feet per mile (650 m/km). Most of the values occurred at the intersection of the gulch with Ruby Creek. The Crystal Gulch deposit was exhausted by 1924. The uranium mineral brookite was identified by Mertie (1936). Concentrates averaged 5 percent cassiterite during the life of the operation. (Ted Almasy, personal communication, 1998). Age of mineralization is unknown, but judged to be Quaternary, based on comparative geomorphological features in southwest Alaska (Bundtzen and Miller, 1997).
Geologic map unit (-154.782324549601, 63.2333922244188)
Mineral deposit model Placer Au-PGE (Cox and Singer, 1986; model 39c).
Mineral deposit model number 39c

Production and reserves

Workings or exploration The placer deposit was mined exclusively by surface-hydraulic methods (Brown, 1926; Mertie, 1936).
Indication of production Yes; small
Production notes Production estimates are lumped with other properties on Ruby Creek, which produced a total of 1,511 ounces (47 kg) of gold prior to 1942.

Additional comments

See also Ruby-Strand (MD069), Birch Gulch (MD073), Holmes Gulch (MD0 72), Encio Gulch (MD063) and Upper Ruby Creek (MD068).

References

MRDS Number A012426

References

Brown, J.S., 1926, The Nixon Fork country: U.S. Geological Survey Bulletin 783-D, p. 97-144.
Bundtzen, T.K., and Miller, M.L., 1997, Precious metals associated with Late Cretaceous-early Tertiary igneous rocks of southwestern Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 242-286.
Cobb, E.H., 1974, Placer Deposits of Alaska: U.S. Geological Survey Bulletin 1374, 213 pages.
Cobb, E.H., 1978, Summary of references to mineral occurrences in the Beaver, Bettles, and Medfra quadrangles: U.S. Geological Survey Open File Report 78-94, 54 pages.
Mertie, J.B., Jr., 1936, Mineral deposits of the Ruby-Kuskokwim region, Alaska: U.S. Geological Survey Bulletin 864-C, p. 115-245.
Reporters Bundtzen, T.K. (Pacific Rim Geological Consulting)
Last report date 6/7/1998