General Information:
Chemical Formula:
[ ](CaNa)Mg4(AL,Fe+++)Si8O22(OH)2
Composition:
(Molecular Weight = 805.17 gm)
Sodium 2.86 % Na
Calcium 4.98 % Ca
Magnesium 12.07 % Mg
Aluminum 2.51 % Al
Iron 1.73 % Fe
Silicon 27.91 % Si
Hydrogen 0.25 % H
Oxygen 47.69 % O
Empirical Formula:
CaNaMg4Al0.75Fe3+0.25(Si8O22)(OH)2
IMA Status:
Approved IMA 1978
Name Origin:
Named for Howard J. Winch, Geological survey of India.
Physical Properties:
Cleavage:
[110] Good, [110] Good
Color:
blue violet or cobalt blue.
Density:
2.97
Diaphaniety:
Translucent to Subopaque
Hardness:
5-6 - Between Apatite and Orthoclase
Luster:
Vitreous (Glassy)
Streak:
bluish white
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