Composition of Coal (CO-07)
To many people coal is a black, somewhat shiny rock that burns. Most coals are not simple, uniform substances but consist of bright and dull bands and are complex mixtures of several basic groups of organic compounds.

Coal petrologists study coals to determine their composition. The term maceral is used to describe groups of chemically and physically distinct substances that have unique properties. For example, vitrinite is a maceral in the bright-banded part of coal, and fusain represents dull material. By microscopic examination coal samples can be classified according to maceral composition.

Coal petrographic studies can tell us much about the environment in which the coal formed and about the chemical nature of coal. Chemical properties are useful in determining ways that coal can be used. If coal is needed someday to make synthetic natural gas or petroleum products, petrographic information about the coal will be necessary for designing the process.

Our Hoosier State Beneath Us: Coal

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