Rare Metals: Tin, Tungsten, Molybdenum, Lithium, Tantalum, and Niobium Deposits

Abstract

Rare metal ore deposits and occurrences of Sn-W and W-Mo-Be greisen/stockwork and vein-type, Sn-polymetallic skarn, Sn placers, sedimentary Li, Li-bearing Li-F granites, pegmatites, and ongonites are mainly associated with late Triassic-early Jurassic and Middle Jurassic-early Cretaceous highly differentiated granites and are well-known in Eastern Mongolia, Mongolian Altai, and South Mongolia. Commercial tin deposits occur as small- and medium-sized eluvial and alluvial placers sourced from Sn-W greisen and vein deposits. Many of the Sn-W greisen/stockwork and quartz vein and placer deposits were mined in the last century. Beryllium-bearing pegmatites are common, but Be is mainly a by-product of W-Mo deposits. Other Be resources could be Be-bearing tuffs in Cretaceous volcanic rocks. Lithium is known to occur in pegmatites; however a recent discovery was made of a new type of sedimentary lithium deposit. Other future sources of Li could be Li-F granites and Li-ongonite. The Li-F-bearing granites also contain Ta and Nb; the latter is known from Nb-Zr-REE deposits associated with alkaline rocks in Lake zone of Western Mongolia.