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monoclinicuncommonBorates
Colemanite
CaB3O4(OH)3·H2O
This specimen of Colemanite displays a strong green fluorescence under long-wave UV light, indicating its characteristic luminescent properties. In natural light, it typically appears as colorless to white, often forming blocky or prismatic crystals.
Colemanite Physical Properties
Mohs Hardness
4.5Crystal System
monoclinicLuster
vitreousStreak Color
whiteCleavage
Perfect on {010}, good on {001}, distinct on {100}Fracture
unevenSpecific Gravity
2.42Colors
colorless, white, yellowish, grayishTransparency
transparentType Locality
Boron, California, USA; Death Valley, California, USA; Bigadiç, TurkeyMineral Group
BoratesUses
boron source, fiberglass production, ceramics, detergents, agriculture, collectorAssociated Minerals
borax, ulexite, gypsum, calcite, celestine, sulfurRarity
uncommonGeological Context
Colemanite is a secondary borate mineral that forms in evaporite deposits, particularly in arid lacustrine environments where boron-rich waters evaporate. It is often found in association with other borate minerals in ancient lake beds.
