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

Jayasree Thomas ¹, M. S. Riyazulla ¹, S. Subramanian ², V. N. Vasudev ³, C. S. Gundewar ⁴

Affiliations
1 Indian Bureau of Mines, G G Palaya, Bangalore-560022, IN
2 Department of Metallurgy, Indian Institute of Science, Bangalore-560012, IN
3 Australian Indian Resources, SBI Colony,7th Main, 111 Block, Bangalore-560034, IN
4 Indian Bureau of Mines, Indira Bhavan, Civil lines, Nagpur-400001, IN

Abstract

Cobalt mineralisation in the Kalyadi copper-Cobalt deposit in the Hassan district, Karnataka, is mostly in sulphidic banded, feldspathic cherty quartzite. Electron microprobe study conducted on sulphide concentrates from this deposit revealed that cobalt up to 3.21 wt% is present exclusively in pyrite grains, whereas it is absent in chalcopyrite and arsenopyrite. From this, it infers that pyrite crystallized first, followed by chalcopyrite and arsenopyrite with most cobalt present in the mineralizing system replacing Fe in the paragenetically early-Formed pyrite,thereby rendering the system deficient in cobalt during later crystallization of chalcopyrite and arsenopyrite.

Keywords

Pyrite, Cobalt, Electron Microprobe Study, Kalyadi, Karnataka.

Full Text

     

N. V. Chalapathi Rao ¹, Mohan Ram ¹, A. T. Sutaone ¹, C. S. Gundewar ¹

Affiliations
1 Ore Dressing Division, Indian Bureau of Mines, Ministry of Mines, L-8, MIDC-Hingna Road, Nagpur - 440 016, IN

Abstract

Gold in the form of cuprian grains is reported based on Electron Probe Micro Analyzer (EPMA) study of a sample received from the chromite tailing dumps of South Kallapani mines, Sukinda Ultramafic Belt, Jajpur district, Orissa The cuprian gold grains vary in size from 3 microns to 10 microns and are found as disserninations within the chromite host-phase Chromite is one of the eallest minerials to form whereas hydrothermal process is charactenstic of gold The association of chromite and gold grains is therefore unusual and highly intcresting Textural features suggest that the gold gram are more likely to be genuine primary inclussions within the host chromite rather than being late stage hydrothermal products filling up cavities or open spaces A preliminaray account of characterization studies of gold grains involving back-scattered electron imaging, X-ray element 'dot' mapping, and qualitative elemental scanning are presented.

Keywords

Cuprian Gold, Chromite, Sukinda Valley, Kaliapani mines, Jajpur district Orissa.

Full Text