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Birnessite (Photo)

Year of discovery: 1956 (Birness, UK), 1943 (Japan)

Locality list: 102 localities of birnessite

• NaMn₄O₈,3H₂O
• (Na,Ca,K)(Mn⁴⁺,Mn³⁺)₄O₈,3H₂O
• [Na⁺][Mn³⁺Mn⁴⁺₃O₈]^-,3H₂O

• Class: Oxide - Hydrate
• Radioactive: Very weak
• Formed on dehydration of Buserite.

• Color: Black
• Streak: Black
• Luster: Submetallic
• Diaphaneity: Opaque

• Habit: Earthy

• Hardness: 1.5
• Density: 3.0

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=5.2, b=2.9, c=7.3, β=103.2