Boracite
Chemical compound
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Boracite is a magnesium borate mineral with formula: Mg₃B₇O₁₃Cl. It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system. Boracite also shows pseudo-isometric cubical and octahedral forms. Wikipedia
Formula mass: 392.03 g/mol
Crystal class: Pyramidal (mm2); (same H-M symbol)
Crystal habit: Crystalline, disseminated (pseudocubic)
Crystal system: Orthorhombic
Formula (repeating unit): Mg3B7O13Cl
Luster: Vitreous - adamantine
Mohs scale hardness: 7 - 7.5