Bokan Mountain is underlain by a multiple-phase peralkaline granite that has four types of related mineral deposits or occurrences. Shear zones and fracture-controlled deposits are best typified by the Ross-Adams mine, which has produced uranium and contains remaining resources of thorium, uranium, and yttrium, but no appreciable columbium in a pipe-shaped ore body. Pegmatites, the second type of deposit, are common: 1) within the peralkaline granite and range from small tabular bodies to larger convoluted sheets or pods, and 2) within the border zone pegmatite where they occur as linear bands and variable lenses subparallel to the contact of the Bokan intrusive complex. Typically, they have complex mineralogies and variably elevated quantities of gold, beryllium, columbium, hafnium, REE, tantalum, tin, titanium, thorium, uranium, yttrium, and zirconium. The third type of deposit comprises over 35,000 ft of strike length along five systems of northwest trending mineralized dikes. These dikes radiate from the peralkaline granite into the country rock and contain complex suites of REE, beryllium, columbium, tantalum, thorium, yttrium, uranium, and other economic minerals. Fourth, placer deposits associated with post-glacial sedimentation are suggested by geomorphic evidence and limited sampling data from surface sediments. However, no economic or subeconomic placer deposits were delineated. Numerous prospects and mines and previously unreported mineralized occurrences were examined during this investigation. Nine of the prospects, six of which have not been previously described, were found to have sufficient size and grade to warrant estimation of indicated and/or inferred resources totaling
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