Colemanite - CaB₃O₄(OH)₃ · H₂O

Habit: Colorless to white or gray. Complex crystals; also massive or granular to compact. Adamantine to vitreous luster; transparent to translucent. White streak.

Environment: A common constituent of borate deposits formed in arid alkaline lacustrine environments that are deficient in sodium and carbonate, typically under warm conditions.

Etymology: Named for William T. Coleman (1824-93), pioneer developer of the California borate industry and owner of the mine where the mineral was first found.