Tungsten and tin are very abundant and economically important metals of Mongolia. There are more than 160 primary and placer deposits of these metals, of which only 20 are primary deposits. The tin and tungsten deposits of Central and Eastern Mongolia are genetically associated with Mesozoic granitoids. These granitoids occur widely in the zone of Mesozoic tectonic and magmatic activity. Most of the tin and tungsten deposits are genetically associated with both “normal” and lithium-fluorine types of granitoids. Greisen and quartz-vein type wolframite and cassiterite deposits are associated with the granites of normal composition. Tantalum-bearing lepidolite-albite and amazonite granites are genetically associated with lithium-fluorine granites, ongonites, rare-earth microclinites and rare-element zwitters. The tin-tungsten mineralization of Mongolia is very diverse, and includes hydrothermal and pegmatitic shows as well as skarns. The most commercially viable hydrothermal deposits containing wolframite and quartz and cassiterite, wolframite and quartz. The highest value in the economy have deposits of tungsten and tin, represented mostly by quartz vein, greisen and placer types, although detailed ore genesis studies of the mineralization have not yet been conducted.