MINERAL MATTER IN THE RAJMAHAL COALS - STUDY THROUGH INCIDENT LIGHT-MICROSCOPY AND SCANNING ELECTRON MICROGRAPHY

The Lower Gondwana coals of the Rajmahal group of coalfields have been studied, in detail, under the Petrological and the Scanning Electron Microscopes to elucidate the mode of occurrence of mineral matter and their microstructural relations with organic constituents. Observation s of both the methods reveal the occurrence of mineral matter as massi ve impregnation, intimate intergrowth, superficial mounting, superfici al blanketting, pore filling and solution cavity filling. The absence of microstructures, when observed via incident light microscopy, such as superficial blanketting and superficial mounting in the macerals an d microlithotypes, in general, suggests their elimination during the c ourse of grinding and polishing of the coal pellets: This suggests ske wing of the mineral matter assessment through microscopic examination. The quantitative distribution of mineral matter in the coal lithotype s as observed in SEM is Durain > Clarain > Vitrain > Fusain while the ash analysis of different lithotypes shows the order of dominance of a sh (equivalent to mineral matter) as Durain > Fusain > Vitrain > Clara in.