General Information:
Chemical Formula:
CaAl2(Al2Si2)O10(OH)2
Composition:
(Molecular Weight = 398.18 gm)
Calcium 10.07 % Ca
Aluminum 27.10 % Al
Silicon 14.11 % Si
Hydrogen 0.51 % H
Oxygen 48.22 % O
Empirical Formula:
CaAl4Si2O10(OH)2
Environment:
Commony associated with corundum as an alteration product.
Locality:
Corundum mines at Ekaterinurg Distict, Ural Mountains, Russia.
Name Origin:
From the Greek margaritos - "pearl."
Physical Properties:
Cleavage:
[001] Good
Color:
white, gray, pinkish gray, or yellowish gray.
Density:
2.99 - 3.08, Average = 3.03
Diaphaniety:
Translucent to subtranslucent
Habits:
Lamellar - Thin laminae producing a lamellar structure., Massive - Lamellar - Distinctly foliated fine-grained forms., Scaly - Morphology like fish scales.
Hardness:
4 - Fluorite
Luminescence:
None.
Luster:
Pearly
Streak:
white
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