Collection: Dumortierite

Formula: Al(Al₂O)(Al₂O)₂(SiO₄)₃(BO₃)

The given formula is the anhydrous end-member. Hydrogen incorporation leads to a more complex formula: (Al,◻)[Al₂(O,OH)](Al₂O)₂[SiO₃(O,OH)]₃(BO₃)

Colour: Blue, greenish-blue, violet-blue, pale blue, pink, red

Luster: Vitreous

Hardness: 7 - 8

Specific Gravity: 3.21 - 3.41

Crystal System: Orthorhombic

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