Geology, Geochemistry and Genesis of Manganese Ore Deposits of Vizianagaram District, Andhra Pradesh, India
Manganese deposits of Vizianagaram district, Andhra pradesh shows conformable bands like in
the khondalite suite of rocks of Easteran Ghats complex. The dominant manganese ore minerals
include cryptomelane, psilomelane, pyrolusite, hausmannite bixbyite and wad etc,. Quartz orthoclase,
garnet, kaolinite, hematite and mica are the associated gangue minerals. Presence of high silica and
dominance of CaO over MgO, K2O over Na2O, Ni over CO, Zn and Cu over Pb are the elemental
characteristics of the deposit. Discrete apatite inclusious are identified in quartz and orthoclase.
Continental weathering appears to be the source for manganese and iron. After deposition and
diagenesis, the manganese rich sediments were metamorphosed under granulite facies (max.7000C
and min.6 kb pressure) conditions and subsequent deformation and supergene enrichment produced
the present deposit. The manganese ores are generally of low grade with high phosphorus content.