gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1972.038.299.13 Coexisting Hornblende and Cummingtonite from the Khetri Copper Belt, Rajasthan, India Das Gupta S. P. Geological Survey of India, 5-5-449 Mukaramjahi Road, Hyderabad-1, A.P., India 9 1972 38 299 890 893 26 7 1971 Copyright © 1972, The Mineralogical Society 1972 Summary

Coexisting hornblende and cummingtonite in an amphibolite near Peliwali have been analysed. The rock formed by Fe-Mg addition and Ca removal from pre-existing amphibole quartzites within the altered wall rocks surrounding sulphide lodes. The amphibole compositions are controlled by the bulk composition of the rock. The Mg/(Mg+Fe2+) ratio of the hornblende (0·66) is only slightly higher than that of the cummingtonite (0·64).