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Andalusite [abbr. And ]

Year of discovery: 1798 (El Cardoso de la Sierra, Spain), 1890 (Japan)

Locality list: 404 localities of andalusite

• Al₂SiO₅
• [Al³⁺][Al³⁺][O|SiO₄]^6-

• Class: Nesosilicate - Oxide
• Variety: Viridine (+Mn, Green)
• Variety: Chiastolite (+Carbon inclusions, Cross pattern)
• Insoluble in: HCl
• Substitution pseudomorph: Replaced by Muscovite.

• Polymorph: Kyanite (High pressure, Triclinic)
• Polymorph: Sillimanite (High temperature, Orthorhombic)

• Al => Mn: Kanonaite (Series)

• Color: Gray, Pink, Green
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Granular, Prismatic

• Cleavage: Perfect on {110} (2 planes), Indistinct on {100} (1 plane)
• Hardness: 6.5-7.5
• Density: 3.2

• System: Orthorhombic
• Group: mmm, Pnnm
• Lattice: a=7.8, b=7.9, c=5.6

Etymology: Andalucia district, Spain