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Cryptomelane (Photo)

Year of discovery: 1942 (Tombstone, USA), 1938 (Japan)

Locality list: 200 localities of cryptomelane

• KMn₈O₁₆
• [K⁺][Mn⁴⁺₆][Mn⁴⁺Mn³⁺][O₁₆]^32-

• Class: Cryptomelane group
• Class: Oxide
• Radioactive: Very weak
• Formed by weathering alteration of Rhodonite.

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

• Color: Brownish black, Iron black
• Streak: Brownish black
• Luster: Sub-Metallic
• Diaphaneity: Opaque

• Habit: Earthy
• Aggregate: Amygdalodial

• Cleavage: No
• Hardness: 5-6.5
• Density: 4.6

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