Coexisting Hornblende and Cummingtonite from the Khetri Copper Belt, Rajasthan, India

S. P. Das Gupta
Geological Survey of India, 5-5-449 Mukaramjahi Road, Hyderabad-1, A.P., India

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).

Mineralogical Magazine; September 1972 v. 38; no. 299; p. 890-893; DOI: 10.1180/minmag.1972.038.299.13
© 1972, The Mineralogical Society
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