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Potassic-sadanagaite [abbr. K-Sdg ]

Year of discovery: 1984 (Japan as the first occurence in the World)

Locality list: 4 localities of potassic-sadanagaite

• KCa₂Mg₃Al₂Al₃Si₅O₂₂(OH)₂
• (K,Na)Ca₂(Mg,Fe,Al,Ti)₅(Si,Al)₈O₂₂(OH)₂
• [K⁺][Ca²⁺₂][Mg²⁺₃][Al³⁺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: Sadanagaite (Series)

• Mg => Fe: Potassic-ferro-sadanagaite (Series)

• Al₂ => MgSi: Potassic-pargasite

• Color: Black, Dark brown
• Streak: Pale brown
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Acicular, Prismatic

• Cleavage: Perfect on {110} (2 planes, 120 degree)
• Hardness: 5-6
• Density: 3.3

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=10.0, b=18.1, c=5.4, β=105.6

Synonym: Potassic-magnesiosadanagaite