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BLACK GRANITE RESOURCES OF RAJASTHAN AND THEIR FUTURE PROSPE
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INTRODUCTION
Black granites are categorised as a major exportable commodity amongst the dimension stones in India. India possess11, 114 thousand cubic metres of proved recoverable reserves of black granites. Their probable and possible reserves are 203,057 and 29,370 thousand cubic metres respectively (Brahmanandan and Iyer, 2002). The Rajasthan's share of all categories of total recoverable probable and possible reserves being 4 and 201, 692 thousand cubic metres only. Out of above the reserve estimates of black granites of Rajasthan are only 80.00 million cubic metres ( G.S.I.; 1996-1997) compared to 1385.00 million cubic metres of multicoloured granites.
Recent estimates by Brahmanandan and Iyer (2002) the Rajasthan's share in the total production of all categories of Indian granites of 14,55,013 tonnes is only 3%, indicating that there is a vast scope for enhancing the production of black granites in Rajasthan for indigenous as well as overseas consumption. In this context it may be mentioned that very little attention has been paid in the development of black granites in Rajasthan although they occur in abundunt quantities in almost all the geological horizons between Precambrians to Cretaceous ages. Author's recent field work in different districts of Rajasthan indicate that there is an immense scope for the production of black granites in Rajasthan if a systematic evaluation of such granites is carried out from commercial point of view including the reserve estimates. There is a great need to take up a comparative study of black granites of Andhra Pradesh, Karnataka, Tamilnadu and Orissa with Rajasthan counter parts delineating the different varieties according to dyke wise reserve estimates along with their physical, petrographic, physicomechanical and chemical properties.
Popular black granites of exportable value produced in India are, Joypur Black, Keonjhar Black (Orissa); Kunnam Black (Tamil Nadu); Black granites of Uttar Pradesh and West Bengal; Black Jet of Assam and Meghalaya; Black Galaxy and Jet Black varieties of Andhra Pradesh; Black granite, Black Cheetah and Black zebra (Bihar); Ajapur Galaxy, Maharaj and Tiger Black of  Gujarat.                  
Black Galaxy, Jet Black, Tiger Black and Black Granite (Karnataka) and Black Granite of Madhya Pradesh. 
The only known black granite of Rajasthan is sold under the trade name of Cobra Black, although a large number of varieties are available.
Black granites, in general are least porous with least water absorption values. The true apparent specific gravity is highest for these rocks compared to coloured granites. 
Geological distribution of Black Granites in Rajasthan in given in Table No. 1, A detailed description along with physical, petrographic, mineralogical and chemical characteristic of Black Granites of Rajasthan is being presented in this paper.