gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1973.039.301.11 Ortho- and Clino-Pyroxenes from the Charnockite Series of Amaravathi, Andhra Pradesh, South India Ramaswamy A. Ph.D. Murty M. S. D.Sc. Department of Geology, S.V. University, Tirupati, South India 3 1973 39 301 74 77 13 3 1972 8 5 1972 Copyright © 1973, The Mineralogical Society 1973 Summary

The chemical analyses, structural formulae, and optical data of seven orthopyroxenes and six clinopyroxenes, all from the charnockite series of Amaravathi, are presented. The orthopyroxenes are in the hypersthene-ferrohypersthene range while the clinopyroxenes are in the sahlite range. The aluminous nature of the pyroxene is believed to be the result of high pressure. The clinopyroxenes have the granulite trend on the Wo-En-Fs plot. The tie-line projections and the KD values for the pyroxene pairs indicate conditions of chemical equilibrium around 670 °C for the charnockite series of Amaravathi.