Washington Uranium - 2020

Uranium (Nuclear Minerals) / Exploration, Mining, Marketing, & Acquisitions

A Wikiwand summary indicates that uranium was discovered at the Midnite Mine deposit on the Spokane Indian Reservation, Stevens County, north-east Washington in 1954. The deposit was mined from an open pit 1956–1962 and 1969–1982. Production through 1975 was 8 million pounds (3,600 metric tons) of U3O8. The uranium is contained in autunite, uraninite, and coffinite, with gangue minerals pyrite and marcasite. The ore occurs as disseminations, replacements, and stockworks in Precambrian metamorphic rocks of the Togo formation, in a roof pendant in Cretaceous porphyritic quartz monzonite. Western Nuclear discovered the Spokane Mountain uranium deposit in 1975, two miles (3 km) northeast of the Midnite Mine, and in a similar geologic setting.

Other major Washington state uranium mines included the Sherwood mine, located five miles south of the Midnite mine, and the Daybreak mine, located six miles southeast of Elk, Washington. The Daybreak mine is recognized as the source of the finest museum-quality specimens of autunite and meta-autunite yet found.  For additional information on uranium occurrences in Washington, see: https://www.dnr.wa.gov/Publications/ger_ic46_directory_wa_mines_1969-70.pdf  Sherwood had a co-located uranium mill, while Midnite and Daybreak ores were processed at the Dawn uranium mill, at Ford, Washington.

References of note: 

1.  J. Thomas Nash and Norman J. Lehman (1975) Geology of the Midnite Uranium Mine, Stevens County, Washington – a Preliminary Report, US Geological Survey, Open-File Report 75-402.
   
   
2. David A. Robbins, Applied geology in the discovery of the Spokane Mountain uranium deposit, Washington, Economic Geology, Dec. 1978, pp. 1523–1538.
   
   
3. Ream, Lanny R. (1991), "Two Autunite Localities in Northeastern Washington," Rocks & Minerals Vol. 66, No. 4, pp. 294–297

The above title link also lists other states where uranium has been reported of not necessarily economic importance.

This link presents locations in the state of Washington where uranium and other metals have been reported/mined prior to 1971: https://www.dnr.wa.gov/Publications/ger_ic46_directory_wa_mines_1969-70.pdf