Ramsdellite

General Information:
 Chemical Formula:
MnO2
 Composition:
(Molecular Weight = 86.94 gm)
Manganese 63.19 % Mn
Oxygen 36.81 % O 
 Empirical Formula:
Mn4+O2
 Environment:
Manganese deposits with pyrolucite.
 Locality:
Lake Valley, Sierra County, New Mexico.
 Name Origin:
Named after the American mineralogist, Lewis S. Ramsdell (1895-1975), of the University of Michigan, who first described the mineral.
Physical Properties:
 Cleavage:
[???] Good
 Color:
iron black, black, or steel gray.
 Density:
4.37
 Diaphaniety:
Opaque
 Habits:
Massive - Fibrous - Distinctly fibrous fine-grained forms., Granular - Generally occurs as anhedral to subhedral crystals in matrix., Platy - Sheet forms (e.g. micas).
 Hardness:
3 - Calcite
 Luster:
Metallic
 Streak:
brownish black
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