Rock Creek-Lost Creek Mining Districts

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 focus area is within the district includes the contact between the Pennsylvanian Amsden Formation and Mount Torrey batholith.
Identified resources Historical production of tungsten.
Production Browns Lake mine (1928-1957): produced 625,107 tons with a grade of 0.35% WO3; (1928-1939): 87 tons with a grade of 0.01 troy oz/ton Au, 7.4 troy oz/ton Ag, and 7.3% Cu (Geach, 1972). Lost Creek mine (1952-1956): produced 21,150 tons of ore with a grade of 0.18% WO3.
Status Past mining. Brown's Lake mine closed in 1958 following termination of U.S. Federal stockpiling program.
Estimated resources Unknown.
Geologic maps Geach (1972, figure 65), scale 1:20.000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage.
Favorable rocks and structures Favorable rock types are upper Paleozoic carbonates in contact with quartz monzonite intrusions.
Deposits Brown's Lake mine (MRDS dep_id: 10055833; USMIN Site_ID: MT00027), Lost Creek mining district (USMIN Site_ID: MT00015).
Evidence from mineral occurrences MRDS; USMIN; Pearson, Trautwein, Berger and others (1992); Pearson, Trautwein, Moll and others (1992).
Geochemical evidence Unknown.
Geophysical evidence Hanna and others (1993); Kaufmann and others (1983).
Evidence from other sources None.
Comments It is conceivable magnetic geophysical mapping could lead to the discovery of buried calc-silicate skarn deposits within the Pioneer Mountains. Carbonate formations contacted by silicic intrusions hosting past producing tungsten mines are found throughout the region. The same carbonate rocks and intrusions could occur at other unexplored locations within the Pioneer Mountain range.
Cover thickness and description Part of the Browns Lake deposit is buried under shallow cover.
Authors 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 incomplete.