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A Tungsten-rich Porphyry Molybdenum Occurrence At Bear Mountain, Northeast Alaska.
For Reference Only At Bureau Libraries :64 pages
In 1983, the Bureau of Mines investigated an occurrence of molybdenum and tungsten near Bear Mountain in northeastern Alaska. A mineralized area defined by greater than 600 ppm molybdenum in soils over approximately 100 acres is underlain by an altered complex of rhyolite porphyry, intrusive breccia, and rhyolite porphyry dikes. Soil with at least 500 ppm tungsten also defines an area partially coincident with the molybdenum area. These values are approximately equivalent to 0.1 pct mos2 and 0.06 pct wo3. Soil samples also indicate low-grade niobium (columbium) enrichment. Rock samples from the Bear Mountain occurrence contained 0.1 to 0.8 pct molybdenum and 0.06 to 0.6 pct tungsten. Although sulfide minerals have been leached, the tungsten mineral wolframite comprising both the huebnerite and ferberite end members was identified in rocks and placer concentrates. Zonation between a higher level, silicarich, wolframite-topaz zone and a lower level, central molybdenum-rich, gossan zone with lower tungsten values is evident.
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Alaska Field Operations Center
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division