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Masutomilite (Photo)

Year of discovery: 1974 (Japan as the first occurence in the World)

Locality list: 4 localities of masutomilite

• KLiMnAl₂Si₃O₁₀F₂
• (K,Rb)(Li,Mn,Al)₃(Si,Al)₄O₁₀(F,OH)₂
• [K⁺][Li⁺][Mn²⁺][Al³⁺][F₂|AlSi₃O₁₀]^7-

• Class: Trioctahedral < True mica group < Mica supergroup
• Class: Phyllo-Aluminosilicate - Fluoride
• Radioactive: Very weak

• Mn => Li_0.5Al_0.5: Trilithionite
• Mn => LiSi: Polylithionite

• LiMnAl => Mg₃: Fluorophlogopite
• LiMnAl => Fe₃: Fluorannite

• Color: Pale purple
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Hexagonal platy

• Cleavage: Perfect on {001} (1 plane)
• Hardness: 2.5
• Density: 2.9

• System: Monoclinic, Pseudohexagonal
• Group: 2/m, C2/m
• Lattice: a=5.3, b=9.1, c=10.1, β=100.8

Etymology: Kazunosuke Masutomi (1901-1993), Japanese pharmacist and mineralogist