| Basis for focus area |
MRDS past Be producers; Foley, Jaskula, Piatak and Schulte (2017). |
| Identified resources |
Identified beryllium and fluorite resources; historical production of beryllium (beryl) and fluorite. |
| Production |
Unknown. |
| Status |
Past mining. Episodic exploration 1960s-1980s(?); semi-active exploration by Tertiary Minerals plc since ~2013 (~40 drill holes). |
| Estimated resources |
Beryllium: Resource of 175 million metric tons, contained 47,000 metric tons of BeO, grade of 0.27% BeO, and grade of 0.01% Be (Foley, Jaskula, Piatak and Schulte (2017)). Fluorite: 2015: 6,700,000 tons, 10.8% CaF2 (Indicated mineral resource, 9% CaF2 cut-off); 88,500,000 tons, 0.7% CaF2 (Inferred mineral resource, 9% CaF2 cut-off) [JORC compliant] (Davis and Muntean, 2018). Asarco estimated resources of 110 million tonnes grading 10% CaF2 and Wardell Armstrong International Ltd estimated 85-105 million tonnes grading 9-11% fluorspar at 8% cut-off grade CaF2. The target is part of a larger mineral system estimated by Tertiary Minerals plc at 395 to 615 million tonnes grading 5-7% fluorspar at 2% cut-off grade (Hayes and others, 2017). |
| Geologic maps |
Roberts and others (1967), scale 1:250,000; Long and others (2014), scale 1:48,000; Stewart and Carlson (1978), scale 1:500,000. |
| Geophysical data |
Adequate Rank 1 aeromagnetic and aeroradiometric coverage; See Ponce and Drenth (2020). |
| Favorable rocks and structures |
Mineralization occurs as a skarn-type replacement of flat-lying limestone beneath a quartzite cap. Beryllium is in carbonate rocks and fluorite associated with dikes. Porphyritic felsite dikes (ca. 84 Ma) and aplite in Paleozoic limestone, dolomite, and quartzite, altered to dolomite, greisen/quartz veins, tremolite, phlogopite, and calcite; 6 vein types containing quartz, feldspar, garnet, epidote, feldspar, fluorite, pyrite, muscovite, sphalerite, molybdenite, zoisite, beryl, barite, and Sb sulfosalts. |
| Deposits |
McCullough Butte, Reese and Berry mine (MRDS dep_id: 10044701). |
| Evidence from mineral occurrences |
MRDS; Foley, Jaskula, Piatak and Schulte (2017). |
| Geochemical evidence |
Reportedly elevated W, Sn, Mo, Zn concentrations in a relatively large fluorite deposit (>80 Mt at ~10% CaF2). |
| Geophysical evidence |
Unknown. |
| Evidence from other sources |
Unknown. |
| Comments |
Tin and W reported by Barton (1987). Bismuth and Sc enrichment is inferred from the mineral system/deposit type table (Hofstra and Kreiner, 2020). |
| Cover thickness and description |
Unknown. |
| Authors |
David A. Ponce, Peter G. Vikre. |
| New data needs |
Geophysics, lidar. |
| Geologic mapping and modeling needs |
Would need access to drill hole data for 3D molding. Drill holes may not be deep enough to make it worthwhile. |
| Geophysical survey and modeling needs |
High resolution aeromagnetic and aeroradiometric coverage. |
| Digital elevation data needs |
Lidar inadequate. |
