a white mineral that forms salt deposits of magnesium borate and chloride in orthorhombic crystalline form. Formula: Mg3ClB7O13
boracite in American English
(ˈbɔrəˌsaɪt)
noun
a very hard, brittle, orthorhombic mineral, magnesium borate, Mg3B7O13Cl, formed by the evaporation of salt water: it has a strong pyroelectric property