clarain

clarain, macroscopically distinguishable component, or lithotype, of coal that is characterized by alternating bright and dull black laminae. The brightest layers are composed chiefly of the maceral vitrinite and the duller layers of the other maceral groups exinite and inertinite. Clarain exhibits a silky lustre less brilliant than that of vitrain (q.v.). It seems to have originated under conditions that alternated between those in which durain (q.v.) and vitrain were formed. See also maceral.