Coal
Macerals

The macerals are coalified plant parts that retain the morphology and some properties of the original plant. In many coals, individual macerals can be identified visually. Some macerals include:

In coalification huminite is replaced by vitreous (shiny) vitrinite. Maturation of bituminous coal is characterized by bitumenization, in which part of the coal is converted to bitumen, a hydrocarbon-rich gel. Maturation to anthracite is characterized by debitumenization (from demethanation) and the increasing tendency of the anthracite to break with a conchoidal fracture, similar to the way thick glass breaks.
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