Bear Lodge Mountains District

The Bear Lodge Mountains district in northeastern Wyoming was first prospected in 1875 after the discovery of gold in feldspar porphyry near Warren Peak. Recent exploration in the area has been fostered by both historically known mineralization and by similarities this Tertiary intrusive complex shares with the 30 Ma gold-hosting Cripple Creek igneous complex in Colorado. In addition to gold, mineral values in the Bear Lodge have included rare earth elements (REE), barium, copper, lead, zinc, manganese, niobium, tantalum, thorium, fluorine, and phosphate. Mineralization in the Bear Lodge Mountains includes disseminated, vein, carbonatite, and replacement deposits. The greatest potential for resource development are the REE followed by gold.

Rare Element Resources in October 2014 reported an NI 43-101-compliant (*see footnote on Laramie Mtns page) total high-grade Measured and Indicated (M&I) mineral resource of 15.7 million tonnes (17.3 million tons) averaging 3.11 percent total rare earth oxides at a 1.5 percent cutoff grade, which included M&I resources of 5.4 million tonnes (6 million tons) grading 4.51 percent rare earth oxides at 3 percent cutoff grade.

Gold mineralization occurs within the same large alkaline-igneous complex as the REE mineralization and is comingled with REE in places. On March 15, 2011, Rare Element Resources released an NI 43-101-compliant inferred mineral resource estimate of 26,850 kg (947,000 oz) of gold contained in 69.3 million tonnes (76.4 million tons) averaging 0.42 ppm (0.42 g/tonne; 0.122 oz/ton) using a 0.15 ppm (0.15 g/tonne; 0.004 oz/ton) cutoff grade.

Bear Lodge
Extensive drilling and trenching in the Bear Lodge Mountains contributed to the delineation of significant REE and gold mineralization. [Credit: Wayne M. Sutherland, WSGS]


Patty Webber,