GENESIS OF LEAD-COPPER ORES IN AGNIGUNDALA AREA ANDHRA PRADESH.

Lead-Copper deposits in dolomites, cherty dolomites, quartzites, and calcareous quartzites occur at Bandalamottu, Dhukonda, and Nallakonda of Agnigundala area. The mineralization is mainly controlled by stratigraphic and lithologic features. Galena, sphalerite and pyrite are the dominant ore minerals in dolomites, while chalcopyrite and bornite are dominant in quartzites. Linnaeite, covellite, chalcocite, and bravoite are accessories. In addition to these, X-ray patterns show the presence of violarite, cobaltite, niccolite, stibnite, meneghinite, sternbergite, penroseite, and cuprobismutite. Malachite and azurite are the liberation products of chalcopyrite and bornite during oxidation. The field and mineralogical associations, textural, petrographic and petrochemical features show that Pb, Zn, and Fe sulphides represent a primary sedimentary genesis, subsequently metamorphosed and recrystallized, while copper mineralization is due to later hydrothermal activity. The presence of linnaeite and bravoite indicates low temperature of the order of 300°C and below, low pressure, and low oxidation for the ore formation.