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Potassic-ferro-ferri-sadanagaite

• KCa₂Fe₅Al₃Si₅O₂₂(OH)₂
• (K,Na)Ca₂(Fe,Mg)₃(Fe,Al)₂Al₃Si₅O₂₂(OH,F,O)₂
• [K⁺][Ca²⁺₂][Fe²⁺₃][Fe³⁺₂][(OH)₂|Al₃Si₅O₂₂]^17-

• Class: Ca amphibole subgroup < w(OH,F,Cl)-dominant amphibole group < Amphibole supergroup
• Class: Ino-Aluminosilicate (Double chain) - Hydroxide
• Radioactive: Very weak

• K => Na: Ferro-ferri-sadanagaite

• Fe³⁺ => Al: Potassic-ferro-sadanagaite

• Color: Black
• Streak: Greenish gray
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {110} (2 planes, 120 degree)
• Hardness: 5.5-6
• Density: 4.3

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice (2009): a=9.9, b=18.1, c=5.4, β=105.2