| Basis for focus area |
The focus area is based on significant U production from the Midnite mine, coupled with additional occurrences along prospective contact between the Cretaceous Loon Lake granite and (Precambrian?) Togo Formation (Becraft and Weis, 1963; Nash, 1977). A second part of the focus area along the same contact is about 45 miles northwest of the Midnite mine and was identified based on reports of exploration in 2010 by Castle Creek Silver Inc. and the Lost Creek mine that produced about 13,000 lbs U3O8. |
| Identified resources |
Historical production of uranium. |
| Production |
Midnite mine (1945-1982): 11 million lbs U3O8; Lost Creek mine (1958-1962): about 12,000 lbs U3O8 (Pool, 2017). |
| Status |
Past mining; recent exploration. |
| Estimated resources |
Unknown. |
| Geologic maps |
Campbell and Raup (1964), scale 1:48:000. Miller (1996), scale 1:48,000. Becraft and Weis (1963, plate 1), scale 1:24,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Contact between the Precambrian Togo Formation and Cretaceous Loon Lake granite. |
| Deposits |
Midnite mine (Boyd mine) (MRDS dep_id: 10008500). |
| Evidence from mineral occurrences |
MRDS; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006). |
| Geochemical evidence |
NURE stream silt samples have up to 207 ppm U in the Midnite mine drainage. |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Exploration of the Lost Creek area by Castle Creek Silver Inc. was reported in a press release August 4, 2010. |
| Comments |
Focus area listed as a Magmatic REE-Peralkaline syenite/ granite/rhyolite/alaskite/pegmatite. Only known mineralization is uranium. Enrichment of all other critical commodities listed has been inferred from the mineral system/deposit type table (Hofstra and Kreiner, 2020). |
| Cover thickness and description |
Exposed at the surface. |
| Authors |
Susan Hall, Joshua M. Rosera. |
| New data needs |
Geophysics, mapping, and geochemistry. |
| Geologic mapping and modeling needs |
Higher resolution mapping and geochemistry with a focus on ore trends and controls. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and aeroradiometric coverage. |
| Digital elevation data needs |
Lidar complete. |
