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Itoigawaite

Year of discovery: 1999 (Japan as the first occurence in the World)

Locality list: 3 localities of itoigawaite

• SrAl₂Si₂O₇(OH)₂,H₂O
• [Sr²⁺][Al³⁺₂][(OH)₂|Si₂O₇]^8-,H₂O

• Class: Lawsonite group
• Class: Sorosilicate - Hydroxide - Hydrate

• Sr => Ca: Lawsonite

• Al => Mn: Hennomartinite

• Color: Blue
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent

• Cleavage: Good
• Hardness: 5-5.5

• System: Orthorhombic
• Group: mmm, Cmcm
• Lattice: a=6.0, b=8.9, c=13.2

• Coexist: Natrolite, Jadeite

Etymology: Itoigawa city in Niigata prefecture, Japan, where this mineral was discovered for the first time.