| Basis for focus area |
Tungsten skarn, district outline from USMIN for Site IDs MT00028 and MT00027. |
| Identified resources |
Identified resources of tungsten, Historical production of copper, gold, silver, and tungsten. |
| Production |
Calvert mine (1956-1957 and 1960-1962): 112,800 tons with a grade of 1.1:2% WO3; (Walker, 1963). |
| Status |
Past mining. |
| Estimated resources |
Calvert mine (2016): Unclassified reserve of 128,000 tons grading 1.1% WO3; Brown's Lake mine (1991): 3,300,000 tons grading 0.48% WO3 (Messenger, 2016). |
| Geologic maps |
Horton and others (2017), scale 1:500,000; Zen (1988), scale 1:48,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Skarn developed in Pennsylvanian Amsden Formation near or in contact with Cretaceous plutons. |
| Deposits |
Calvert mine (MRDS dep_id: 10269525; USMIN Site_ID: MT00028). |
| Evidence from mineral occurrences |
MRDS; USMIN; Pearson, Trautwein, Moll and others (1992). |
| Geochemical evidence |
Geochemical reconnaissance in Berger and others (1979). |
| Geophysical evidence |
Hanna and others (1993); Kaufmann and others (1983). |
| Evidence from other sources |
None. |
| Cover thickness and description |
Parts are exposed or buried under shallow cover. |
| Authors |
Kaleb C. Scarberry, Stanley L. Korzeb. |
| New data needs |
High resolution geophysics, lidar, geochemistry, geologic mapping, trace element analysis on skarn related intrusions, and skarns for critical elements. |
| Geologic mapping and modeling needs |
Detailed geologic mapping of known skarn deposits to build exploration model. |
| Geophysical survey and modeling needs |
High resolution aeromagnetic and aeroradiometric coverage can be used to see through structural and soil cover to explore for undiscovered skarn deposits. |
| Digital elevation data needs |
Lidar inadequate. |
