Geochemistry and Macromolecular Structure of Coal

Coal is a complex sedimentary rock derived from plant remains that underwent peatification and subsequent coalification. Coals originated as peat deposits formed in prehistoric swamps through the accumulation of plant substances whose components underwent differing degrees of chemical decomposition and polymerization. The most uniform microscopic constituents of coal, whose morphologically preserved or repolymerized materials retain distinct characteristics, are known as macerais. A brief study of the organic geochemistry of coal and its macerai characteristics will be helpful in clarifying the nature of coal structure and will give a basis for the understanding of coal structural characteristics. Given (1984b) states that even though the organic chemistry of coal has been studied for more than 100 years, the geological factors in coal chemistry have been almost totally ignored. According to Given (1984b), it is the geoscience of coals, or their geochemistry of origin and postburial geological history, that is responsible for the fact that coals are a very diverse set of materials. Consequently, it is only a study based on geological origins of coal chemistry that will enable coal researchers to rationalize the diversity in coal and to express this in a systematic manner.