The petrological characteristics of many of the Permian coal seams of India have a profound and particular influence upon their preparation and utilization properties. Relatively high proportions of ash are largely derived from the finely dispersed sedimentary mineral matter generally present in all coal types. The proportions of the clastic minerals generally increase with those of the "inert" seam constituents and are thus generally greatest in the common "dull" coals. The intimate association of fine mineral matter and "inert" organic constituents in both macroscopic and microscopic bands makes the problems of preparation more difficult. Reduction in the proportions of clastic mineral matter inevitably lowers the content of the "inerts" and thus increases those of the "coking" constituents. Consequently the characteristics of the coke produced vary considerably with the degree of cleaning achieved on the coal. Substantial reduction in the clastic mineral content of the coal charge could be accompanied by significant deterioration in the mechanical strength of the coke produced.