One of a particular assemblage of coal macerals. Exinite (liptinite) is a group consisting of spores, cuticles, resins, and waxes, rich in hydrogen and typical of attrital coals. It includes sparain, cutan, alginite, resinite, and liptodetrinite. Inertinite is charcoal-like, the result of bacterial action or forest fires; high in carbon, relatively inert during carbonization. It includes micrinite, semifusinite, fusinite, sclerotinite, and detrinite. Vitrinite is characteristic of vitrain coal derived from humus; with medium reflectivity. It is subdivided into telinite with visible residual cell-wall material, and collinite which is structureless.