Colemanite Sample
US Borax & Chemical Corp

Colemanite (CaB3O4(OH)3·H2O) is a borate mineral found in evaporite deposits of alkaline lacustrine environments. Colemanite is a secondary mineral that forms by alteration of borax and ulexite.[1]It was first described in 1884 for an occurrence near Furnace Creek in Death Valley and was named after William Tell Coleman (1824-1893), owner of the mine Harmony Borax Works where it was first found.
Colemanite. H 12, L 19 cm
Death Valley National Park, DEVA 33004