Exinite

In coal geology, liptinite is the finely-ground and macerated remains found in coal deposits. It replaced the term exinite as one of the four categories of kerogen. Liptinites were originally formed by spores, pollen, dinoflagellate cysts, leaf cuticles, and plant resins and waxes.

M.C. Stopes introduced the term exinite in 1935 to describe the microscopic constituent of coal, rich in volatiles and relatively rich in hydrogen, that is represented by the exines of spores. C.A. Seyler in 1932, however, used the term with its present meaning, designating the following group of macerals: sporinite, cutinite, alginite (telalginite and lamalginite), resinite.

Macerals (from the same Latin source as 'macerate') are to coal as minerals are to rock. The term was coined by M. C. Stopes in 1935, who wrote

The macerals grouped under the term exinite are not necessarily entirely composed from exines, but appear to have similar technical properties, though little information is so far available on the technological behavior of pure exinite.

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