Recent work on these deposits shows that the simple hydrothermal model does not fit the observed features of these deposits. The gold deposit of Kolar occurs in a high-grade metamorphic terrain closely associated with amphibolites which have been later intruded by granitic rocks. It now seems that the amphibolites, which were primarily basic lava flows, may have been the source of gold while the later granitic rocks helped to mobilize it. The Cu deposits of Khetri and Singhbhum, and the associated uranium ores in the latter, also seem to be primarily syngenetic materials which have been later mobilized through metamorphic processes that gave rise to granitic magmatism which, in turn, mobilized the ore materials. The same model applies to the Pb-Zn deposits of Zawar though no granitic rocks are exposed at the present level of erosion.-J.M.H.