Mineralogical characteristics of coal seams Ia, I and IIa from Bobov Dol Basin, SW Bulgaria

The mineralogical composition of Bobov Dol sub-bituminous coals from the lower part of the coal-bearing formation, was studied using optical microscopy, XRD and SEM-EDS analyses. Clay minerals (smectite, illite and kaolinite) and quartz, are the dominant minerals. Their characteristics indicate predominant terrigenous origin and argue for major detrital input from intermediate to mafic rocks. Accessory epigenetic barite-celestine mineralization, substituting almost completely oxidized siderite crystals and spheroidal aggregates, denotes circulation of meteoric aqueous solutions in the absence of other fracture-filing minerals. Finite glass spheres from the top of the coal seam I indicate synchronous volcanic activity, which did not influence peat formation.