| Basis for focus area |
The focus area includes identified U occurrences in the Spor Mountain mining district (Krahulec, 2018b) and also covers the Spor Mountain cluster of Be deposit. |
| Identified resources |
Identified resources of beryllium (bertrandite). Current producer of beryllium (bertrandite) with historical production of beryllium, fluorite, and uranium. |
| Production |
The Yellow Chief mine produced about 400,000 lbs of U3O8 between 1955 and 1968 (Pool, 2017). Materion (formerly Brush Wellman, Inc.) has mined bertrandite from Topaz Mountain/Spor Mountain district since 1968, yielding over 16 million lbs of beryllium hydroxide. Beryllium production in 2019 alone totaled 320,706 lbs. |
| Status |
Past and active mining for beryllium (bertrandite) at Spor Mountain by Materion, active exploration and mining for fluorite by Ares Strategic Minerals, and historical mining for fluorite and uranium. |
| Estimated resources |
8.8 million tons at 0.248% Be Proven and Probable reserves estimated by Materion (Spor Mountain) to be enough for 75 years mine life at current (2020) production levels. Unknown for fluorite, lithium, or uranium. |
| Geologic maps |
Lindsey (1979), scale 1:62,500. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Oligocene Spor Mountain Formation; informal beryllium tuff member where it contains clasts of local carbonate country rock. Li-Topaz rhyolite ash flows, flows and domes of two ages; ~25.6 Ma at Spor Mountain (Ayuso and others, 2020) and 6.5 Ma at Topaz Mountain. These rocks are part of an east-west belt of Miocene topaz rhyolites and Be, U, F deposits and occurrences; with revisions to regional geochronology (Foley and others, 2020). |
| Deposits |
Spor Mountain district (MRDS dep_id: 10400503), Yellow Chief. |
| Evidence from mineral occurrences |
MRDS; UMOS (Utah Geological Survey, 2021); published mining company data; International Atomic Energy Agency (2020b); U.S. Environmental Protection Agency (2006). |
| Geochemical evidence |
Published geochemical data for whole rocks showing relatively high values of Li and presence of Li-bearing clay minerals. |
| Geophysical evidence |
Limited to none. |
| Evidence from other sources |
See Krahulec (2018b). |
| Comments |
Uranium, with associated F (fluorite), Be (bertrandite) and Li, is associated with structures and also formed in a porous member of the Spor Mountain Formation. Fluids interacted with breccias comprised of carbonate clasts derived from local Paleozoic carbonate rock which were entrained in alkalic rhyolitic tuff (Lindsey, 1998). Uranium minerals have not been found, and uranium is presumed to be within the fluorite. Speculatively, uranium within hydrothermal fluids derived from volcanic rocks may have been transported as U-F in solution. When these fluids encountered carbonate clasts within tuffs, F combined with Ca in the carbonates to form fluorite (CaF2), entraining U within the mineral matrix. Volcanogenic Be and U, vein and replacement fluorspar. Spor Mountain is the global leader in beryllium production. Current exploration and development in preparation for fluorite mining at Lost Sheep, which would be the only domestic fluorite operation. Known enrichment/past production of U and Li, and limited geochemical sampling of Spor Mountain tailings indicates potential HREE enrichment. |
| Cover thickness and description |
Variable, primarily at the surface. |
| Authors |
Nora K. Foley, Albert H. Hofstra, Susan Hall, Joshua M. Rosera. |
| New data needs |
Regional aeromagnetics; mine waste geochemical sampling; geologic mapping mainly for establishing distribution of units having high lithium, fluorine, beryllium and uranium potential. |
| Geologic mapping and modeling needs |
Geochronological and metallogeny studies of volcanic units is underway (USGS funded project). |
| Geophysical survey and modeling needs |
High-resolution, Rank 1 aeromagnetic and radiometric surveys. |
| Digital elevation data needs |
Lidar inadequate. High-resolution lidar would define mine waste and tailings under reclamation for examination of mining waste potential. |
