General Information:
Chemical Formula:
K(Mn++++,Mn++)8O16
Composition:
(Molecular Weight = 734.59 gm)
Potassium 5.32 % K
Manganese 59.83 % Mn
Oxygen 34.85 % O
Empirical Formula:
KMn2.5+8O16
Environment:
Commonest of the hard, black, fine-grained manganese oxides formerly called psilomelane.
IMA Status:
Approved IMA 1963
Locality:
Chindwara, India.
Name Origin:
From the Greek for hidden and black, as the identity of this common, black mineral is lost in the group of other black Mn-bearing oxides.
Physical Properties:
Color:
black, gray, or blue gray.
Density:
4.36
Diaphaniety:
Opaque
Habits:
Cryptocrystalline - Occurs as crystals too small to distinguish with the naked eye., Botryoidal - "Grape-like" rounded forms (e.g.. malachite)., Massive - Uniformly indistinguishable crystals forming large masses.
Hardness:
6-6.5 - Orthoclase-Pyrite
Luster:
Sub Metallic
Streak:
brownish black
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