| Basis for focus area |
REE-bearing veins. Reported REE minerals in veins; polygon drawn to include related USMIN and MRDS localities of similar type and geologic setting. |
| Identified resources |
Identified thorium resources. |
| Production |
Unknown. |
| Status |
Past exploration. |
| Estimated resources |
Estimated Th reserves of 104,300 metric tons (115,000 tons) of vein material averaging 4.0% ThO2 and low overall concentrations (average about 0.05%) REO (Staatz, Armbrustmacher and others, 1979). |
| Geologic maps |
Newton and others (1960), scale 1:60,730; Miller and Burmester (2004), scale 1:100,000; Burmester and others (2011), scale 1:24,000; Breckenridge and others (2011), scale 1:24,000; Breckenridge and others (2014), scale 1:75,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Veins cutting Mesoproterozoic fine-grained arkose and quartz diorite. |
| Deposits |
Hall Mountain (MRDS dep_id: 10143778), Hall Mountain Group (1 to 14) (USMIN Site_ID: ID00025). |
| Evidence from mineral occurrences |
MRDS; USMIN. |
| Geochemical evidence |
Total REE concentrations range from 0.00111 to 0.197%; ThO2 concentrations range from 0.0095 to 21% in Staatz (1972a) and Staatz and others (1974). Staatz, Armbrustmacher and others (1979). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Thorite, allanite, monazite, sphene, zircon, ilmenite. |
| Comments |
Diabase sill hosted, no evidence for felsic rocks. Hydrothermal veins are not really properly classified in this hierarchy. |
| Cover thickness and description |
Variable. |
| Authors |
Karen Lund, Thomas P. Frost, Joshua M. Rosera. |
| New data needs |
Geophysics. |
| Geologic mapping and modeling needs |
Quadrangle-scale mapping adequate. |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and aeroradiometric coverage. |
| Digital elevation data needs |
Lidar in progress. |
