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D. Narasimhan ¹, T. S. Sunilkumar ¹, E. V. S. S. K. Babu ², N. Krishna Rao ¹

Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN
2 Department of Earth Sciences, University of Cambridge, GB

Abstract

Palladian melonite, containing upto 7% palladium is reported for the first time from the uranium ores, Jaduguda Mines.

Keywords

Mineralogy, Palladian Melonite, Uranium, Singhbhum, Bihar.

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N. Krishna Rao ¹, T. S. Sunilkumar ¹, D. Narasimhan ¹

Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN

Abstract

Uranium in the sandstone-hosted uranium deposit at Domiasiat, Meghalaya is mainly associated with organic matter (OM), which is also enriched in several trace elements, viz. Zn, Pb, Ni, V, Co, Ba, Sn, Mo, Cr, Ag, P etc. This paper is an attempt to characterize and discuss the origin of the OM and the associated uranium.

The OM occurs in several forms - lumps, layers, veins, dispersions, fracture fillings, coatings and impregnations. Based on structural features and optical properties, seven types of OM are identified. The structural and compositional features indicate that the OM is type II kerogen with macerals mainly belonging to liptinite group. Some of the primary structures have acted as loci of deposition of uraninite and other inorganic minerals like pyrite, marcasite, sphaleri'te and apatite, thereby giving rise to certain interesting textural features. Development of asecondary granular structure and bIades of secondary OM are features related to maturation. Uranium occurs in the form of uraninite of three generations, minor coffinite and a distinct organo-uranyl complex.

Both the South Khasi granite batholith and the tuffaceous matter related to Sylhet Trap episode appear to be the source for various inorganic elements enriched in the OM. From structures and association it appears that uranium fixation in the OM has taken pIace both due to anaerobic reduction by bacterial H₂S and complexation to form organo-uranyl complexes. The latter, on maturation, was reduced to form fine precipitates of uraninite dispersed in the OM. It is suggested that the maturity of OM, extending up to semi-anthracitic stage, has taken place due to radiolysis and radiogenic heat.

Keywords

Organic Matter, Uranium Ore, Sandstone, Domiasiat, Meghalaya.

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N. Krishna Rao ¹, T. S. Sunilkumar ¹, D. Narasimhan ¹

Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN

Abstract

Native gold, etectrum with a wide spectrum of compositional variations between gold and silver, and native silver are identified based on ore microscopic and scanning electron microscopic studies in the copper ores of Khetri-Kolihan, Rajasthan and probable mode of origin is discussed.

Keywords

Economic Geology, Gold, Silver, Copper, Rajasthan.

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N. Krishna Rao ¹, T. S. Sunilkumar ², D. Narasimhan ²

Affiliations
1 B-41, Taxila Apartments, Sardar Patel Road, Secunderabad 500 003, IN
2 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad 500 016, IN

Abstract

Nature of occurrence of native gold in the uranium ore from Jaduguda and copper ore from Mosabani in the Singhbhum Shear Zone, Bihar, is described. Preliminary data on the gold contents of different ore deposits along the shear zone, and their beneficiation products, are also reported. The native gold particles appear to be of detrital origin.

Keywords

Economic Geology, Gold, Detrital Origin, U-Cu Ores, Singhbhum Shear Zone, Bihar.

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K. K. Sinha ¹, N. Krishna Rao ², V. L. Shah ³, T. S. Sunilkumar ²

Affiliations
1 Prem Mandir, Anugrah Narayan Road, Kadamkuan, Patna - 800 003, IN
2 Ore Dressing Section, Bhabha Atomic Research Centre, Hyderabad - 500 016, IN
3 Atomic Minerals Division, Begumpet, Hyderabad - 500 016, IN

Abstract

Though the stratigraphic succession in the Precambrian of Singbhum-Orissa region of the Indian shield given by Saba et al. is widely accepted, there are several contentious issues whieh have been hotly debated over the years. The occurrence of uraninite and pyrite bearing quartz-pebble conglomerate at the base of Iron Ore Group (lOG) as well as the Dhanjori Group has indicated the necessity for a revision in the stratigraphic succession in view of the temporal significance of such conglomerate the world over.

The conglomerate contains a significant population of zircon, chromite and shows a typical minor and trace element composition. The zircon has morphometric properties similar to those found in several members of the Singhbhum Granite Complex. The presence of detrital chromite and high Cr content indicate the occurrence of older mafics/ultramafics in the provenance along with the Singhbhum Granite Complex. It is suggested that some mafic and ultramafic members presently grouped within the IOG may represent such "older greenstones". The IOG as well as the Dhanjori Group with basal QPC horizon lie over a basement of Singhbhum Granite-Greenstone Complex. From available evidences it is surmised that both IOG sensu stricto (the BIF sequence and associated ferruginous cherts. greywackes and acid-intennediate volcanics) and the Dhanjori Group represent late Archaean (2500-3000 Ma) supracrustals and hence are nearly coeval. The Singhbhum Group north of the shear zone represents early Proterozoic supracrustals.

Keywords

Stratigraphy, Quartz-Pebble Conglomerate, Detrital Zircon, Singhbhum Craton, Bihar.

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T. S. Sunilkumar ¹, D. Narasimhan ¹, N. Krishna Rao ¹

Affiliations
1 Ore Dressing Section, Bhabha Atomic Research Centre, Begumpet, Hyderabad - 500 016, IN

Abstract

The occurrence of authigenic apatite with uraninite, pyrite, sphalerite and galena within organic matter is a characteristic feature of the sandstone-type uranium deposit at Domiasiat, Meghalaya. Apatite occurs in the form of thin hexagonal basal plates and its identification is confirmed by x-ray diffraction. The authigenic apatite in this specific association points towards diagenesis in euxenic conditions of marine affinity.

Keywords

Mineralogy, Economic Geology, Apatite, Uranium, Organic Matter, Meghalaya.

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