Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass (vitreous). It is derived from the cell-wall material or woody tissue of the plants from which coal was formed. Chemically, it is composed of polymers, cellulose and lignin.
Vitrinite Reflectance (Ro%): Vitrinite reflectance (Ro%) is an important geochemical parameter used to assess and evaluate the thermal maturity of sedimentary rocks, particularly those rich in organic matter, such as shales. It is a measure of the reflectivity of vitrinite—a type of maceral (organic component of coal and sedimentary rock)—when viewed under a microscope using oil immersion and reflected light. It is expressed as a percentage (Ro%), vitrinite reflectance increases with greater burial depth and thermal exposure, making it a reliable indicator of the maximum temperature a rock has experienced during its geological history.