Several important uranium deposits associated with fluorspar and beryllium are located in parts of Thomas Range area. The mineralization is found in dolomites and dolomitic limestones of Paleozoic age and sandstones, tuffs, and rhyolites belonging to the Tertiary Spor Mountain and Topaz Mountain Formations.

The pipes, veins, and nodules of fluorspar are replaced by uranium. Veins and disseminations of radioactive fluorspar opal and overgrowths of secondary minerals are found in rhyolites, tuffs, carbonate rocks, and breccias. The radioactivity in sandstones and conglomerates emanates from weeksite, beta-uranophane, zircon, gummite, etc. Uraninite occurs as rare inclusions in fluorite, gummite, and zircon. It also occurs as highly oxidized rare aphanitic grains disseminated in a few ore deposits. The results of the present investigations may influence the initiation of future exploration programs in the Thomas Range mining district.

Hydrothermal fluids of deep-seated magmatic origin rich in U, V, Th, Be, and F reacted with the country rocks. The nature and sequence of wall-rock alteration and its paragenetic relationship with the ores have been determined. The mineralization is confined to the altered zones. The ore bodies in the sedimentary rocks and the breccias are located in the fault zones. More than 1,000 faults are present in the area, greatly complicating mineral prospecting. The wall-rock alteration is very conspicuous and can be used as a valuable tool in mineral exploration.

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