The appearance of the surface of a substance in reflected light. The term is used particularly in describing minerals. Types of luster include (1) metallic, like metals or the mineral pyrite;(2) vitreous, like glass or quartz; (3) adamantine, exceedingly brilliant, like diamond; (4) resinous, like resin, or sphalerite; (5) dull, not bright or shiny, like chalk.See Delustrant.