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Kyanite [abbr. Ky ], Cyanite

Year of discovery: 1789 (World), 1897 (Japan)

Locality list: 53 localities of kyanite

• Al₂SiO₅
• [Al³⁺][Al³⁺][O|SiO₄]^6-

• Class: Nesosilicate - Oxide
• Insoluble in: HCl

• Polymorph: Sillimanite (High temperature, Orthorhombic)
• Polymorph: Andalusite (Low pressure, Orthorhombic)

• Al => Mn: Kanonaite

• Color: Grayish blue, Gray
• Streak: Colorless
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Prismatic

• Cleavage: Perfect on {100} and {010} (2 planes), Parting on {001} (1 plane)
• Hardness: 5.5 [001] - 7 [100], Large variation depending on crystallographic directions
• Density: 3.6

• System: Triclinic
• Group: (-1), P(-1)
• Lattice: a=7.1, b=7.9, c=5.6, α=90.0, β=101.1, γ=106.0

Etymology: Kyanos (Blue) in Greek