Occurrence of precious metals in Ultramafic hosted magnetite of J. C. Pura belt, Western Dharwar Craton, Karnataka

摘要

Occurrence of discrete gold and silver grains in the Archaean ultramafic rocks is rare with very few exceptions. In India gold grains have been reported from chromiferous sequences of Nuggihalli and Sukinda ultramafic. Here occurrences of gold and silver grains in various shape and sizes with varying concentration are reported for the first time from ultramafic rocks of Meso-Archaean Jayachamarajapura (J.C.Pura) belt. Preliminary characterization studies of gold (3 grains; 3-6u. in size; oval, rounded and flaky in shape) and silver grains (single grain; oval in shape and <6u in size) along with back-scattered images, X-ray 'dot' element mapping and quantitative elemental scanning are presented which suggest their hydrothermal origin.