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Cuspidine [abbr. Csp ]

Year of discovery: 1876 (Monte Somma, Italy), 1965 (Japan)

Locality list: 4 localities of cuspidine

• Ca₄Si₂O₇F₂
• Ca₄Si₂O₇(F,OH)₂
• [Ca²⁺₄][F₂|Si₂O₇]^8-

• Class: Cuspidine group
• Class: Sorosilicate - Fluoride
• Fluorescence: UV excitation (Franklin, NJ only, Yellow-Purple)

• Color: Colorless, Yellowish brown
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent

• Cleavage: Distinct on {100} (1 planes), Imperfect on {122} (1 plane)
• Hardness: 5-6
• Density: 3.0

• System: Monoclinic
• Group: 2/m, P2₁/b
• Lattice: a=10.9, b=10.6, c=7.6, β=110.1