The possibility of using lithium in batteries to power electric vehicles and as fuel for thermonuclear power has focused attention on the limited resources of lithium other than in pegmatite minerals. The Clayton Valley, Nev., subsurface lithium brine has been the major source of lithium carbonate since about 1967, but the life of this brine field is probably limited to several more decades at the present rate of production. Lithium is so highly soluble during weathering and in sedimentary environments that no lithium-rich sedimentary minerals other than clays have been identified to date. The known deposits of lithium, such as the clay mineral hectorite and the lithium-rich brines, occur in closed desert basins of the Southwest in association with nonmarine evaporites. However, the ultimate source for the lithium in these deposits may be from hydrothermal solutions. The search for previously unreported deposits of nonpegmatitic lithium should consider its probable association, not only with nonmarine evaporite minerals, but also with recent volcanic and tectonic activity, as well as with deposits of boron, beryllium, fluorine, manganese, and possibly phosphate.
