| Basis for focus area |
The focus area includes collapse breccia pipe U occurrences within the Little Mountains district in Wyoming (Gregory and others, 2010) and deposits with similar geology in the Pryor Mountains of Montana (Dahlkamp, 2010). Here hexavalent U minerals with accompanying silica fill open space in solution collapse features in the Mississippian Madison Limestone (Dahlkamp, 2010). No comprehensive genetic model has been proposed for these deposits. |
| Identified resources |
Historical production of uranium and vanadium. |
| Production |
45,042 lbs U3O8 (with an average grade of 0.27%) and 30,187 lbs V2O5 (with an average grade of 0.29%) were produced from about 21 properties (deposits) in the Pryor Mountains area between 1956 and 1964 (Van Gosen and others, 1996). 177,078 lbs U3O8 (with an average grade of 0.39%) and 205,736 lbs V2O5 (average grade of 0.75%) were produced from properties of the Little Mountain district (Van Gosen and others, 1996). Ore from the Pryor Mountains area were reported at 0.5 to 0.8% U3O8 with a maximum of 1.27% (Elevatorski, 1976). |
| Status |
Past mining. |
| Estimated resources |
Van Gosen and others (1996) estimated a mean of 170 metric tons of U3O8 and 140 metric tons of V2O5. |
| Geologic maps |
Gregory and others (2010), scale 1:500,000; Horton and others (2017), scale 1:500,000; Pierce (1997), scale 1:250,000; Blackstone (1974), scale 1:24,000; Green and others (1999), scale 1:125,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Mississippian Madison Limestone with mineralized areas occurring along the flanks of Porcupine Creek anticline (in Wyoming). |
| Deposits |
Swamp Frog mine (MRDS dep_id; 10019872), Dandy (Pryor Mountain) mine (MRDS dep_id; 10019868), Sandra mine (MRDS dep_id; 10148982). |
| Evidence from mineral occurrences |
MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006). |
| Geochemical evidence |
Only uranium minerals present in Wyoming are tyuyamunite and metatyuyamunite (Elevatorski, 1976). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
Hand-picked, high-grade ore from the Swamp Frog mine contained 31.8% U and 9.88% V (Van Gosen and others, 1996). Several small historical mines in Wyoming, with mining occurring from 1956 until 1966 (Elevatorski, 1976). |
| Cover thickness and description |
Variable. |
| Authors |
Susan Hall, Jay A. Gunderson, Ranie M. Lynds. |
| New data needs |
Geologic mapping, geochemistry, geophysics. |
| Geologic mapping and modeling needs |
Large-scale mapping of individual deposits (1:12,000 or larger), paired with sedimentological and geochemical study. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and aeroradiometric surveys. |
| Digital elevation data needs |
Lidar complete in Wyoming, no lidar in Montana. |
