The term luster refers to the appearance of a fresh surface of a mineral in reflected light. The two basic types of luster are metallic and non-metallic.
Minerals with metallic luster look shiny like metals. Gold, silver, and copper have metallic luster. Other minerals have a metallic luster as well.
Gold (top left), galena (top right), and copper (bottom) exhibit metallic luster. (Photographs by Parvinder Sethi)
Minerals with non-metallic luster can be divided into groups of minerals with earthy, waxy, vitreous (glassy), adamantine (diamond-like), resinous (like resin), pearly, silky, or dull luster.
These pictures show examples of different types of non-metallic luster. Limonite (upper left) has an earthy luster. Amber (upper right), which is not a mineral because it is organic, has a resinous luster. Quartz (lower left) has a vitreous luster. Diamond (lower right) has adamantine luster. (Photographs by Parvinder Sethi)