Studies of copper minerals in old workings for copper in Yenambail, Khamman District, Andhra Pradesh

Abstract

The old workings for copper about 2 miles north of Yenambail (Long. 80° 41′, Lat. 17° 41′) in Khammam District were first reported by C. Mahadevan in 1943, while in Hyderabad Geological Survey and later were taken up for detailed prospecting in summer, 1957, by the staff and students of the Geology and Geophysics Departments of the Andhra University. The work was sponsored by the Government of Andhra Pradesh.

The formations in this area consist of hornblende schists, phyllites, magnesian limestones and quartzites, striking N.E.-S.W. to N.N.E.-S.S.W., dipping towards west, with concordant intrusions of quartz veins. Some of the quartz veins carry the copper minerals—chalcopyrite, chalcocite and covellite along with other sulphide minerals like pyrite and arsenopyrite. Malachite, azurite and cuprite are conspicuous as thin films and coatings on the surfaces of quartzites and silicified limestones. The ore minerals have been studied both in the field and the laboratory and the results are briefly recorded. The textures are due to replacement and colloform zoning. The paragenetic sequence of the minerals is arsenopyrite, pyrite, chalcopyrite, covellite and chalcocite. Chalcopyrite, pyrite and arsenopyrite are considered to be hypogene and covellite and chalcocite are of supergene origin.