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Paul Kibler Sims and George Phair, Geologic plan map of the Copper King Mine, Larimer County, Colorado, 1952, U.S. Geological Survey


Copper King Mine

The Copper King mine in Larimer County was opened during World War I in an unsuccessful attempt to mine copper and zinc ore. The mine was abandoned when it couldn't cover its costs. In the summer of 1949, Brown and Ismert prospected the Copper King mine dump and found it to be highly radioactive. Following the discovery of pitchblende on the dump, the mine was reopened, and it was worked until 1953 for uranium. A total of 652 tons of ore that contained an average of 0.28 percent triuranium octoxide was shipped.


Sims, Paul Kibler, George Phair, and Robert Hadley Moench. "Geology of the Copper King Uranium Mine, Larimer County, Colorado." Trace Elements Investigations 424. U.S. Department of Interior, Geological Survey. 1955. Accessed July 31, 2020.

Granger, Harry C. and Robert U. King. "Uranium in the Copper King Mine, Black Hawk No. 1 Claim, Larimer County, Colorado." Trace Elements Memorandum Report 128-A. U.S. Department of Interior, Geological Survey. 1951. Accessed July 31, 2020.

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