Brown matter is found in varying amounts in the attrital matter of all splint and semisplint coals; it is occasionally present in the attritus of bright coals. It consists of cell-wall degradation matter and the contents of cells, which in thin sections are brown and semitranslucent. The term has no exact equivalent in the Stopes-Heerlen nomenclature. Constituents with a reflectance between that of vitrinite and fusinite may correspond in part to brown matter. Some brown matter is identical with semifusinite and massive micrinite.