Mineral Chemistry and IMA Nomenclature of Amphibole Minerals of Amphibolite Sills from Chhotanagpur Granite Gneiss Complex (CGGC), Southern Sonbhadra, Central India

In southern part of Sonbhadra District, near the Rihand Dam, low to medium grade amphibolites of Paleoproterozoic age are exposed. The outcrops are in the form of sills that occur at places in the Chhotanagpur Granite Gneiss Complex (CGGC). The essential mineralogical constituents of the amphibolite are amphibole-plagioclase-chlorite-biotite-iron oxides. Based on the mineral chemistry and interpretation as per the international mineralogical association (IMA) nomenclature scheme, amphiboles in the analysed amphibolite rock samples have been identified as magnesio-hornblende, magnesio-ferri-hornblende and edenite. � 2024 Geological Society of India, Bengaluru, India.