The mineralogy and chemical composition of lignitic, subbituminous and bituminous coal and coal-ash samples from six Bulgarian deposits, namely Maritza West (MW), Sofia (S), Maritza East (ME), Bobov Dol (BD), Pernik (P) and Balkan (B), were studied and a model for comparative characterization of their composition was done. Major minerals identified in the crystalline matter of Bulgarian coals are commonly quartz, kaolinite, illite, calcite, pyrite, plagioclase, K-feldspar and gypsum and occasionally dolomite, siderite, Fe oxyhydroxides and Fe sulphates. Some genetic features of the inorganic matter in coal and coal ash are described and compared. The coals studied show high detrital (P, B, ED, ME) or high authigenic (SI MW) mineral abundance with sulphide-sulphate (P, ED, ME, MW) or mixed carbonate and sulphide-sulphate (B, S) authigenic mineral tendencies. The high-temperature ashes of these coals belong to sialic (P), sialoferricalcic (B, ED), sialoferric (ME) or ferricalsialic (MW, S) chemical types. They have high (B, P, ED) or low (ME, MW, S) silicate mineral abundance with sulphate (B, P, ME, MW, S) or oxyhydroxide (BD) mineral tendencies.