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Hollandite [abbr. Hol ]

Year of discovery: 1906 (Gowari Wadhona mine, India), 1960 (Japan)

Locality list: 25 localities of hollandite

• BaMn₈O₁₆
• (Ba,K,Ca,Sr)(Mn⁴⁺,Mn³⁺,Ti,Fe³⁺)₈O₁₆
• [Ba²⁺][Mn⁴⁺₆][Mn³⁺₂][O₁₆]^32-

• Class: Cryptomelane group
• Class: Oxide

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

• Mn³⁺ => Fe: Ferrihollandite

• Mn⁴⁺ => Ti: Ankangite

• Mn₈ => FeTi₇: Henrymeyerite

• Color: Silver gray, Black
• Streak: Black
• Luster: Metallic
• Diaphaneity: Opaque

• Cleavage: Distinct, Parting on {001} (1 plane)
• Hardness: 4-6
• Density: 5.0

• System: Monoclinic
• Group: 2/m, I2/m
• Lattice: a=10.0, b=2.9, c=9.7, β=91.0