Liptinite

In coalgeology,liptiniteis the finely-ground andmaceratedremains found incoaldeposits.It replaced the termexiniteas one of the four categories ofkerogen.Liptinites were originally formed byspores,pollen,dinoflagellatecysts,leafcuticles, andplantresins and waxes.

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

Macerals(from the same Latin source as 'macerate') are to coal as minerals are to rock. The term wascoinedbyM. C. Stopesin 1935, who wrote

"The concept behind the word ‘macerals’ is that the complex of biological units represented by a forest tree which crashed into a watery swamp and there partly decomposed and was macerated in theprocess of coal formation,did not in that process become uniform throughout but still retains delimited regions optically differing under the microscope, which may or may not have different chemical formulae and properties. These organic units, composing the coal mass I propose to call macerals, and they are the descriptive equivalent of the inorganic units composing most rock masses and universally called minerals. "

The macerals grouped under the termexiniteare 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.