Optical
properties
(may vary
slightly according to source area)
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Uniaxial (-) |
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Crystal system |
Hexagonal |
Z = 2 |
Habit Hexagonal prism, columnar
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Refractive index: 1.576 – 1.582 |
Birefringence: 0.006 |
Dispersion : 0.014
weak |
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Pleochroism: definite green, blue green , yellow green
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Fluorescence : usually inert but
may fluoresce orange-red to red |
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Chemical composition |
Beryllium aluminum silicate (Be3 Al2(Si6O18) |
Molecular
Weight 537.50 gm |
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Cell Parameters |
a
9.263 Å |
c 9.199
Å |
c/a
0.9931 |
Vol. 683.6 Å3 |
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Ordinary ray two lines in the red at 6830 and 6800 Å, a third at 6370 Å and a line in the blue at 4775 Å - Extraordinary ray - doublet at 6830 Å and 6800 Å
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