Calvert Hill District

Region West, Northwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

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.