Abstract:
The occurrence of rhythmic layering of chromite and host serpentinites in the deformed
layered igneous complexes has been noticed in the Nuggihalli schist belt (NSB) in the western Dharwar
craton, Karnataka, South India. For this study, the chromitite rock samples were collected from
Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore
microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The
ferritchromite compositions are characterized by higher Cr number (Cr/[Cr + Al]) (0.68–0.98) and
lower Mg number (Mg/[Mg + Fe]) (0.33–0.82) ratios in ferritchromite compared to that of parent
chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg,
Al, Cr, and Fe between the chromite, surrounding silicates (serpentines, chlorites), and fluid during
serpentinization.
