Mount Tolman

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

Information leading to the delineation of this focus area

Basis for focus area Mount Tolman porphyry copper deposit and surrounding area.
Identified resources Identified resources of copper and molybdenum. Historical production of gold, molybdenum, and tungsten.
Production Unknown.
Status Past mining.
Estimated resources Drilling, underground exploration, and bulk sampling have outlined Proven and Probable reserves of 2.4 billion tons of ore with an average grade of 0.093% MoS2 and 0.09% Cu; the cutoff grade used was 0.048% MoS2. Metallurgical testing resulted in recoveries of 80% of the molybdenite and 80% of the chalcopyrite. The deposit represents a recoverable reserve of 1.9 million tons MoS2 and 1.73 million tons of Cu. A mine plan designed by AMAX would have recovered 727,260 tons MoS2 and 662,400 tons Cu. The AMAX plan was based on mining approximately 900 million tons of ore averaging 0.10% MoS2 and 0.09% Cu and a waste to ore ratio of 0.83:1 (Derkey and others, 1990).
Geologic maps Washington Division of Geology and Earth Resources (2016), scale 1:100,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage. Excellent gravity on deposit but only fair regionally.
Favorable rocks and structures Intrusive rocks of the Eocene to Paleocene Keller Butte pluton.
Deposits Mount Tolman mine (MRDS dep_id; 10155557; USMIN Site_ID: WA00005).
Evidence from mineral occurrences MRDS; USMIN; Derkey and others (1990).
Geochemical evidence Ore contains 0.163 g/t Re (John and others, 2017).
Geophysical evidence Unknown.
Evidence from other sources Unknown.
Comments Focus area is entirely within the Colville Reservation. The Mount Tolman deposit is owned (1990) by the Colville Confederated Tribes. Estimated resources rank the Mount Tolman deposit as the third or fourth largest molybdenum deposits in the world after Climax and Quartz Hill. Whole-rock analyses indicate the Mount Tolman rocks contain 0.3-0.5% Ti02, and if recoverable, the deposit could produce titanium.
Cover thickness and description Exposed at surface and reaches to some depth along veins.
Authors Daniel W. Eungard.
New data needs High resolution mapping, geophysics, and lidar.
Geologic mapping and modeling needs Mapping of one quadrangle at 1:24,000 scale or better resolution.
Geophysical survey and modeling needs High resolution aeromagnetic and aeroradiometric survey.
Digital elevation data needs Lidar inadequate for most of focus area.