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Sapphirine [abbr. Spr ]

Year of discovery: 1819 (Fiskenæsset old harbour, Greenland), 1976 (Japan)

Locality list: 5 localities of sapphirine

• Mg₄Al₈Si₂O₂₀
• (Mg,Al)₈(Al,Si)₆O₂₀
• (Mg,Fe)_4-xAl_4+xAl_4+xSi_2-xO₂₀
• [Mg²⁺₄][Al³⁺₄][O₂|(Al₂SiO₉)₂]^20-

• Class: Sapphirine group < Sapphirine supergroup
• Class: Ino-Aluminosilicate (Single chain) - Oxide
• Insoluble in: HCl

• Color: Pale blue, Bluish gray, Pale green
• Streak: Colorless
• Luster: Vitreous
• Diaphaneity: Transparent

• Cleavage: Indistinct on {100}, {010}, and {001} (3 planes)
• Hardness: 7.5
• Density: 3.4

• System: Monoclinic (2M, 4M), Triclinic (1A, 3A, 5A) (Layer-stacking polytype)
• Group: 2/m, P2₁/c
• Lattice: a=11.3, b=14.4, c=9.9, β=125.5