Co-Rich Lithiophorite in Manganese Ores of the Bonai-Keonjhar Belt, Orissa

Co-Rich Lithiophonte is reported for the first time from low-grade Mn ores of the Bonai-Keonjhar belt (Jamda-Koira valley), Orissa. It occurs in two distinct Litho-Host associations, (i) lateritic zone capping Mn-ore horizon and (ii) shear zone-controlled siliceous manganese ore. It mostly appears as thinly banded and as Vug-Filled linings, in close association with cryptomelane. It occurs as Micron-Sized acicular to pea-shaped crystallites in the first litho association and as coarse, radiating crystals showing Zig-Saw pattern arrangement in the second association Co content is low (CoO 0 14 0 8%) in the Fine-Grained variety whereas in the Coarse-Grained variety it ranges up to 2% (CoO 0 14 2 00%). Appreciable quantity of Ni (N10 0 15-1 5%) is observed along with Co only in Coarse-Grained variety. The mechanism of Co-Entry into the two varieties of supergene lithiophorite through adsorption has been discussed Report of Co in terrestrial Mn-ore has opened up new potential in this part of Orissa.