Abstract
Manganese ores at Kutinga occur as distinctly conformable bands in the khondalite suit of rocks of Eastern Ghats complex. The dominant manganese ore minerals include cryptomelane, psilomelane, pyrolusite, hausmannite, lithiophorite and wad. Quartz, chalcedony, orthoclase, garnet and kaolinite are the associated gangue minerals. Presence of high iron, high phosphorous, low to medium silica and dominance of CaO over MgO, K2O over Na2O, Ni over Co, Zn over Pb and Cu over Pb are the characteristics of this manganese deposit. Phosphorous occurs as discrete apatite inclusions within the quartz and orthoclase; and also adsorbed in the secondary manganese and iron minerals. Field characters, mineralogy and geochemistry of manganese ores suggest their formation as chemical precipitates, and the source of which appears to be continental erosion. Manganese formation along with the country rocks have been metamorphosed under granulite facies conditions, affected by granitisation and subsequently undergone supergene enrichment to give rise to the present deposit. These ores will be amenable to removal of silica, but will not respond well to removal of iron and phosphorous by physical beneficiation.
