Region Central, North Central; Rocky Mountains
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area The focus area includes uranium occurrences hosted in the Edgemont district hosted in the Inyan Kara Group in Wyoming and South Dakota. Roll-front deposits are found in six sandstone horizons in the Lakota and Fall River Formations (Boberg, 2010; Dahlkamp, 2010).
Identified resources Historical production and identified resources of uranium.
Production Between 1952 and 1973 just over 100 properties produced about 6 million pounds of U3O8 and 4.4 million lbs V2O5 from the Black Hills area, with grades averaging 0.21% U3O8 and 0.3% V2O5 (Dahlkamp, 2010). This production includes production in the northern Black Hills (see Hauber focus area).
Status Past mining. Planned in situ recovery project in the Dewey-Burdock area of South Dakota.
Estimated resources The Dewey-Burdock deposit has in-place resources of about 17 million pounds of U3O8 in the Measured and Indicated categories, and another ~700,000 pounds of U3O8 in the Inferred category (Yovich and Cutler, 2020).
Geologic maps Martin and others (2004), scale 1:500,000; McLaughlin and Ver Ploeg (2006), scale 1:100,000; Strobel and others (1999), scale 1:100,000; Wilson and DeWitt (1995) scale 1:100,000; Brobst (1961), scale 1:24,000; Cuppels (1963), scale 1:24,000; Gott and Schnabel (1963), scale 1:24,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Cretaceous Inyan Kara Group (Lakota and Fall River Formations).
Deposits Wyoming: Wicker-Baldwin prospect (MRDS dep_id: 10018730), Elk Mountain (MRDS dep_id: 10135277), Foster (MRDS dep_id: 10305721), Alray uranium mine (MRds dep_id: 10018729), L Shuck property (MRDS dep_id: 10303465).
Evidence from mineral occurrences MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006).
Geochemical evidence Wyoming: ore of metatyuyamunite from Wicker-Baldwin Prospect (Elevatorski, 1976). South Dakota: ore of uraninite, pitchblende, coffinite, carnotite, autunite, uranophane and tyuyamunite in sandstone roll-front type deposits (DeWitt and others, 1986; Yovich and Cutler, 2020).
Geophysical evidence No data.
Comments Primarily located in South Dakota with smaller prospects and minor past production in Wyoming. Azarga Uranium Corp. and Powertech USA Inc. prepared a NI 43-101 report for the Dewey-Burdock ISR Project in Custer and Fall River counties, South Dakota (Graves and Cutler, 2020). The New Haven Group is the largest of over 100 producing mines in the Edgemont district. In situ resources remain at the Dewey-Burdock deposit. In Wyoming, past production documented from the Wicker-Baldwin prospect and Elk Mountain mine with other notable prospects (Elevatorski 1976).
Cover thickness and description Variable. Inyan Kara crops out at surface within focus area, but uranium bearing zones may be several hundred feet below surface, overlain by younger Cretaceous rocks and surficial deposits.
Authors Susan Hall, Ranie M. Lynds, Darren J. Johnson.
New data needs Geological mapping at 1:24,000 scale, geochemical data, geophysical data.
Geologic mapping and modeling needs Surficial mapping at 1:24,000 scale and 3D subsurface modeling in South Dakota. No mapping in Wyoming needed.
Geophysical survey and modeling needs High-resolution, Rank 1 aeromagnetic and radiometric surveys.
Digital elevation data needs Lidar adequate.