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Ottrélite, Ottrelite

Year of discovery: 1842 (Ottré, Belgium), 1927 (Japan)

Locality list: 6 localities of ottrélite

• MnAl₂SiO₅(OH)₂
• (Mn, Fe, Mg)Al₂SiO₅(OH)₂
• [Mn²⁺][Al³⁺₂][(OH)₂|O|SiO₄]^8-

• Class: Chloritoid group
• Class: Nesosilicate - Oxide - Hydroxide

• Mn => Fe: Chloritoid
• Mn => Mg: Magnesiochloritoid

• Color: Grayish green
• Streak: Greenish gray
• Luster: Vitreous
• Diaphaneity: Translucent

• Cleavage: Perfect on {001} (1 plane), Indistinct on {110} (2 planes)
• Hardness: 6-7
• Density: 3.5

• System: Monoclinic
• Group: 2/m, C2/c
• Lattice: a=9.5, b=5.5, c=18.2, β=101.7