Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

B. Chattopadhyay ¹, R. S. Rajawat ¹, K. N. Mathur ², Gajanand ², G. L. Dwivedi ³

Affiliations
1 Regional Petrology Laboratory, Geological Survey of India, Jaipur-302004, IN
2 Geochemical Laboratory, Geological Survey of India, Jaipur-302004, IN
3 Mineral Physics Laboratory, Geological Survey of India, Jaipur-302004, IN

Abstract

Lohawat Meteorite is a differentiated silicate rich aerolite of the high calcium howardite type. Unquestionable magmatic signature is stamped by ophitic, intersertal and spinifex texture, corona and vesicular structures, as seen in lithic fragment clasts. The simple mineralogy has been discussed in terms of the system olivine-clinopyroxene-plagioclase-silica. Varietal texture and compositional features suggest that the meteorite has sampled terrains of distinctly different genetic history.

Keywords

Meteorite, Aerolite, Howardite, Rajasthan.

Full Text

     

P. R. Golani ¹, R. S. Rajawat ¹, N. C. Pant ², M. S. Rao ³

Affiliations
1 Geological Survey of India, AMSE Wing, Central Zone, Seminary Hills, Nagpur - 440 006, IN
2 Geological Survey of India, EPMA Laboratory, NIT-5, Faridabad - 121 001, IN
3 Geological Survey of India, PPOD, AMSE Wing, Bangalore - 560 078, IN

Abstract

Primary gold occurs with sulfides in Paleoproterozoic Aravalli rocks in the Bhukia area of Banswara District, Rajasthan. It occurs as microscopic grains of various shapes, mainly in arsenopyrite and lollingite. With a combined approach of ore petrologic and EPMA studies, we report high purity gold, native bismuth and alloys of gold-bismuth and bismuth-tellurium which best approximate to the rare minerals maldonite and wehrlite respectivety. The fineness of gold ranges between 934 and 995. Preliminary estimates on temperature using arsenopyrite composition coupled with rare presence of spherulitic graphite indicate the temperature of equilibration of around 550°C for the coexisting mineral phases of pyrrhotite, arsenopyrite and lollingite.

Keywords

Economic Geology, Gold Mineralogy, Bismuth, Maldonite, Wehrlite, Lollingite, Bhukia, Aravalli, Rajasthan.

Full Text