Platinum is only one of a group of related metals consisting of osmium, iridium, palladium, rhodium, and ruthenium. They are not only associated together but also are generally alloyed, and are called, therefore the “platinum metals.” They are very heavy, insoluble in most acids, melt at temperatures of 1,549 degree to 2,700 degree C, and range in hardness from 4.8 to over 7. Iridium is the heaviest metal and osmium the hardest.
Platinum is invariably associated with basic igneous rocks and with the ore minerals characteristic of these rocks. Most of the platinum of the world is intimately associated either with chromite or nickel. Even platinum placers are derived from basic rocks rich in chromite. The platiniferous nickel ores also contain copper and appreciable quantities of gold and silver.
In India, reported values of platinum group of metals worthy of attention are from the pre-cambrian mafic/ultramafic complexes in Sukinda and Nausahi sectors of Orissa and Sitampudi in Tamil Nadu. Geological Survey of India carried out sampling of the chromite ore bodies and their associated rocks. It was observed that the incidence of Platinum group of metals is much less in chromite bodies but it is somewhat more, of 20 to 100 ppb (parts per billion) in the chromite horizons.
Seeing the association of platinum with chromite and its deposits in ultramafic rocks in Jharkhand state of India, presence of platinum cannot be ruled out. Till today no detail research work has been done on the possibilities of platinum in the chromite deposit areas in Jharkhand State. Jojohatu, Hatgamariya, Keshargariya, Roroburu, Chitungburu, Kimsiburu, Kittaburu, Kusmita, Gurgaon, Tonto and Janoa-Ranjrakocha areas must be targeted for platinum deposits.
Chromite deposits of Jharkhand had a pioneering role in the early history of chromite exploitation in India. Small deposits of chromite ore are confined to the southern part of Singhbhum district in Jharkhand. Such deposits are exposed around Jojohatu, Hatgamariya, Keshargariya, Roroburu, Chitungburu, Kimsiburu, Kittaburu. Small occurrences of chromite are also found at Kusmita, Gurgaon, Tonto and Janoa-Ranjrakocha areas. Many of the deposits have been prospected by private parties but abandoned afterwards. The deposits are rather scattered and small and the grade is generally inferior (30-40% Cr2O3).
Jojohatu lies about 25 km to the west of Chaibasa, the district headquarters of Singhbhum. The Jojohatu ultramafic body is spread in three blocks with a cumulative length of 8 km in N-S direction and over a width of 3 km. These blocks are named successively from North to South as Kimsiburu, Kittaburu and Roroburu-Chitungburu. The ultrabasic rocks with which chromite is associated is intrusive into the rocks of Iron Ore Super Group represented in the area.
In one report of B.D. Sharma and others, Chalcopyrite concentrates from the Singhbhum district, India, contained 25-70 ppb Pt, which is greater than amounts found in rocks and chromite. Platinum group of metal are also reported in Kinkel and Kurdeg area of Simdega District.
Sharma, B.D. Economic Geology; May 1966; v. 61; no. 3; p. 592-597; DOI: 10.2113/gsecongeo.61.3.592