Boracite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameBoracite
Chemical FormulaMg₃B₇O₁₃Cl
Mohs Hardness7.5
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavageindistinct {110}
Fractureconchoidal
Specific Gravity2.95
Colorscolorless, white, gray, yellowish, greenish, bluish
Transparencytransparent
Type LocalityKalkberg hill, Lüneburg, Lower Saxony, Germany
Mineral GroupBorates
Usescollector, minor_boron_ore
Associated Mineralsgypsum, anhydrite, halite, carnallite, sylvite
Rarityuncommon
Description
Boracite forms small, well-formed crystals, often pseudocubic, with a vitreous to adamantine luster, typically appearing colorless, white, yellowish, or greenish.
Geological Context
This rare borate mineral is found primarily in evaporite deposits, particularly within salt domes, where it crystallizes from highly concentrated boron-rich brines.
