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Manjiroite

Year of discovery: 1965 (Japan as the first occurence in the World)

Locality list: 6 localities of manjiroite

• NaMn₈O₁₆,nH₂O
• (Na,K)Mn₈O₁₆,nH₂O
• [Na⁺][Mn⁴⁺₆][Mn⁴⁺Mn³⁺][O₁₆]^32-,nH₂O

• Class: Cryptomelane group
• Class: Oxide - Hydrate
• Radioactive: Very weak

• Na => K: Cryptomelane
• Na => Ba: Hollandite
• Na => Pb: Coronadite
• Na => Sr: Strontiomelane

• Color: Dark grayish brown
• Streak: Brownish black
• Luster: Earthy
• Diaphaneity: Opaque

• Habit: Massive

• Cleavage: No
• Hardness: 7
• Density: 4.3

• System: Tetragonal
• Group: 4/m, I4/m
• Lattice: a=9.9, c=2.9

Etymology: Manjiro Watanabe (1891-1980), Japanese mineralogist of Tohoku University