Abstract:
Gorceixite, a Ba-Al alunite supergroup mineral, associated with ferromanganese ores of the Precambrian Eastern Ghats Group is reported for the first time from Odisha. The characteristics of gorceixite are described using optical microscopy, XRD, FTIR, Raman, SEM-EDAX and EPMA techniques. The Odisha gorceixite is subhedral, with a broadly prismatic habit and occasional twinning. The calculated formula of present gorceixite is (Ba-0.54 Ca0(0.39) Sr-0.05)(Sigma 0.98) Al-2.96 (PO4)(2.05)(OH)(5).H2O. The Ba is partly substituted by Ca and Sr. Texture of the ores indicates that during supergene alteration, earlier silicate minerals, like celsian (Ba-feldspar), were replaced by gorceixite.