Gaudefroyite

General Information:
 Chemical Formula:
Ca4Mn+++3-x(BO3)3(CO3)(O,OH)3
 Composition:
(Molecular Weight = 582.85 gm)
Calcium 27.51 % Ca
Manganese 23.56 % Mn
Boron 5.56 % B 
Hydrogen 0.13 % H 
Carbon 2.06 % C 
Oxygen 41.18 % O 
 Empirical Formula:
Ca4Mn3+2.5(BO3)3(CO3)O2.25(OH)0.75
 IMA Status:
Approved IMA 1964
Physical Properties:
 Cleavage:
None
 Color:
black.
 Density:
3.35 - 3.5, Average = 3.42
 Diaphaniety:
Subopaque
 Hardness:
6 - Orthoclase
 Luster:
Adamantine - Resinous
 Streak:
brown
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