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Richterite (Photo) [abbr. Rct, Ri ]

Year of discovery: 1865 (Långban, Sweden), 1937 (Japan)

Locality list: 21 localities of richterite

• Na₂CaMg₅Si₈O₂₂(OH)₂
• Na₂Ca(Mg,Fe)₅Si₈O₂₂(OH)₂
• [Na⁺][Ca²⁺][Na⁺][Mg²⁺₅][(OH)₂|(Si₄O₁₁)₂]^14-

• Class: Na-Ca amphibole subgroup < w(OH,F,Cl)-dominant amphibole group < Amphibole supergroup
• Class: Inoslicate (Double chain) - Hydroxide

• Na₂ => Ca: Tremolite

• Mg => Fe: Ferro-richterite (Series)

• OH => F: Fluoro-richterite

• NaMg => []Al: Winchite
• NaMg => []Fe: Ferri-winchite

• NaSi => CaAl: Edenite

• MgSi => Al₂: Katophorite

• Mg₂Si₂ => Al₄: Taramite

• Color: Brown, Reddish brown, Yellow, Grayish green
• Streak: White
• Luster: Vitreous
• Diaphaneity: Translucent

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {110} (2 plane, 120 degree), Perfect on {100} (1 plane)
• Hardness: 5-6
• Density: 3.1

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=9.9, b=18.0, c=5.3, β=104.3

Etymology: Theodor Richter (1824-1898), German mineralogist