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Columbium- and Rare-earth Element-Bearing Deposits At Bokan Mountain, Southeast Alaska.
Available for Reference Only At Bureau Libraries :196 pages
From 1984 through 1987, the Bureau of Mines investigated numerous prospects and new discoveries of columbium, rare-earth elements (ree), uranium, zirconium, and other metals associated with the multiphased peralkaline granite at Bokan Muntain, southeastern Alaska. This report summarizes the mineral evaluations and estimates indicated and inferred resources for those prospects containing significant tonnage and grade. Approximately 96.2 million lb cb2o5 (43 pct of the tonnage at a grade exceeding 0.125 pct cb2o5), 11.8 million lb u3o8, 27.9 million lb tho2, 133.0 million lb y2o3, 637.6 million lb zro2, and 241 million lb rare earth oxides (reo) are estimated to be contained within nine deposits totalling 37.8 million tons (at least 80 pct of resource tonnage also exceeds 0.5 pct y2o3 + reo). Generally, half of the reo content is composed of the heavy yttrium subgroup. Several deposits also contain beryllium and tantalum; 2.1 million lb of ta2o5 and 8.9 million lb of beo were estimated. These estimates would likely be substantially increased with additional exploration. Four deposit types were investigated: shear zones and fracture- related deposits, pegmatites, mineralized dikes, and placers. Mineralized dikes contain most of the beryllium, columbium, tantalum, yttrium, zirconium, and ree resources, whereas shear zones and fracture-related deposits (Ross-Adams Mine) contain the principal uranium resource. Pegmatites are similarly mineralized, as are dike deposits, and contain low levels of gold. Placer potential is suggested, but no deposits were found.
Available for Reference Only At Bureau Libraries
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division