Rare earth deposits in India - An outline of their types, distribution, mineralogy-geochemistry and genesis
Sarkar, S. C.; Dwivedy, K. K.; Das, A. K.
published: Nov 27, 1995
ArtNo. ESP136000501010, Price: 19.00 €
Rare earth deposits in India are divided here into two principal types: endogenic and exogenic. While the former includes some carbonatites, metamorphic-metasomatic veins, the latter comprises coastal or beach placer, in land placer and offshore placer. As of today, the endogenic deposits do not appear to be very much attractive from exploitational point of view. Mainly beach placers are mined in India at present. Monazite is the principal ore mineral for REE in India, although xenotime holds out some prospect for the future. Of India's estimated reserve of 5 million tonnes of monazite, 70-75 % occur in beach placer and the rest in the inland and offshore varieties. Monazite-content of beach sands may be upto 11 wt%. Th02 ranges between 8-10.5 %. Average Sigma REO 60 %. Inland placers contain either monazite or xenotime as the principal REE-bearing mineral. Of late, work on inland placer has started for xenotime. Factors controlling placer formation are: (1) provenance, (2) physico-chemical properties of the minerals in the placer, (3) physico-chemical ambience, the source rocks/earlier deposits are exposed to, and (4) physical process of concentration. In the development of India's beach placer deposits, granites, granitic pegmatites, migmatites, gneisses, charnockites, leptynites and khondalites provided the necessary source and the tropical climate with heavy rainfall and strong wave action was especially conducive to the concentration of the placer-minerals in suitable locales.