Vitrinite

Vitrinite is a maceral, a major constituent of many coals and some sedimentary rocks, derived primarily from woody plant tissue that has undergone coalification. It forms during peat formation and burial, as plant cell walls are transformed by heat and pressure into a carbon-rich, relatively mineral-free material. Vitrinite is typically the most abundant maceral in many coal beds and is commonly accompanied by inertinite and liptinite in varying proportions depending on the peat's original composition and diagenetic history.

In reflected-light petrography, vitrinite shows relatively high reflectance compared with other coal macerals and can range in luster from dull to glassy. It is usually homogeneous in texture and can appear pale brown to dark brown in transmitted light. The mean vitrinite reflectance is a standard measure of coal rank and thermal maturity in petroleum geology; as burial temperature and time increase, vitrinite reflectance generally increases, enabling assessments of coal quality, maturation histories, and kerogen potential.

Vitrinite content is quantified as part of maceral analysis in coal studies. It provides insight into coal properties such as gas yield, coking behavior, and combustion characteristics. While vitrinite is the principal constituent in many coals, other maceral groups—such as inertinite (oxidized or char-like material) and liptinite (lipid-rich components)—also contribute to the overall petrographic composition and affect coal behavior under processing and use.