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Lawsonite [abbr. Lws ]

Year of discovery: 1895 (Reed station, USA), 1938 (Japan)

Locality list: 64 localities of lawsonite

• CaAl₂Si₂O₇(OH)₂,H₂O
• [Ca²⁺][Al³⁺₂][(OH)₂|Si₂O₇]^8-,H₂O

• Class: Lawsonite group
• Class: Sorosilicate - Hydroxide - Hydrate
• Insoluble in: HCl

• Ca => Sr: Itoigawaite

• Color: Colorless, White, Pale blue
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Rectanglar, Granular

• Cleavage: Perfect on {001} (1 plane), Poor on {110} (2 planes)
• Hardness: 7.5
• Density: 3.1

• System: Orthorhombic
• Group: mmm, Cmcm
• Lattice: a=5.8, b=8.8, c=13.1