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Slawsonite

Year of discovery: 1977 (Martin Bridge formation, USA), 1980 (Japan)

Locality list: 10 localities of slawsonite

• SrAl₂Si₂O₈
• (Sr,Ca)Al₂Si₂O₈
• [Sr²⁺][(AlSiO₄)₂]^2-

• Class: Tecto-Aluminosilicate
• Fluorescence: Short UV excitation (Reddish purple)

• Sr => Ca: Anorthite, Dmisteinbergite, Svyatoslavite
• Sr => Ba: Celsian, Paracelsian

• Sr_0.5 => Na: Stronalsite

• SrAl => (Na,K)Si: Anorthoclase
• SrAl => RbSi: Rubicline
• SrAl => NaSi: Albite, Kumdykolite, Lingunite
• SrAl => KSi: Orthoclase, Adularia, Microcline, Sanidine

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

• Habit: Prismatic

• Cleavage: Perfect on {001} (1 plane), Distinct on {010} (1 plane)
• Hardness: 5.5-6.5
• Density: 3.3

• System: Monoclinic, Triclinic
• Group: 2/m, P2₁/a
• Lattice: a=8.9, b=9.3, c=8.3, β=90.3