KIMBERLITE MINERALS FROM VARGEM (MINAS GERAIS) AND REDONDAO (PIAUi) DIATREMES, BRAZIL; AND GARNET LHERZOL]TE XENOLITH FROM REDONDAO DIATREME

Garnet, diopside and Mg-ilmenite have been analyzed from the Vargem diatreme, near Coromandel, State of Minas Gerais, and conlirmed to be comparable to similar minerals from kimberlites in South Africa, Siberia and the United States. Similar minerals occur downstream from the Vargem kimberlite in placer deposits in which diamond is found. The Redondão diatreme in southwest State of Piaul also contairs kimberlitic garnets as well as several xenoliths of crustal and mantle rocks. One xenolith, although extensively serpentinized, was originally a garnetJherzolite comparable in texture and garnet chemistry to those from kimberlites in Southern Africa.