Welshite

General Information:
 Chemical Formula:
Ca2Sb+++++Mg4Fe+++Si4Be2O20
 Composition:
(Molecular Weight = 765.25 gm)
Calcium 5.24 % Ca
Magnesium 12.70 % Mg
Beryllium 2.36 % Be
Iron 7.30 % Fe
Silicon 14.68 % Si
Antimony 15.91 % Sb
Oxygen 41.81 % O 
 Empirical Formula:
CaSbMg4Fe3+Si4Be2O20
 IMA Status:
Approved IMA 1978
Physical Properties:
 Cleavage:
None
 Color:
brown, reddish black, orange brown, or deep tan.
 Density:
3.77
 Diaphaniety:
Subtranslucent to Opaque
 Hardness:
6 - Orthoclase
 Luster:
Subadamantine
 Streak:
light brown
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