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Powellite
Powellite

Sillimanite
Sillimanite



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Sillimanite

Powellite and Sillimanite Optical Properties

Optical Properties

Luster

Greasy, Subadamantine
Vitreous, Subadamantine, Silky

Pleochroism

In deeply colored specimens: blue greenAnthony et al
Colourless to pale brown to yellow

Dispersion

0.030.02
0.005 1
👆🏻

Transparency

Transparent
Transparent, Translucent

Refractive Index

1.974-1.9841.653-1.685
1 3.25
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Optic Character

-
-

Crystal System

-
Orthorhombic

Birefringence

-99990.020-0.022
0 0.296
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Clarity

Transparent
Transparent

Powellite and Sillimanite Optic Character

Powellite and Sillimanite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Powellite and Sillimanite Physical Properties like crystallographic symmetry, pleochroism,etc. in the crystal. Some of the optical properties are refractive index, luster, optic character, pleochroism etc. Prominent among these is Powellite and Sillimanite optic character. You might have noticed your gemologist rotating the gemstone while testing it. Rotating a gemstone along its optic axis helps in determining its optic character.

Powellite and Sillimanite Transparency

Similar to their colors, Powellite and Sillimanite transparency can also be used as criteria for their primary identification. Although transparency cannot be the only criteria for gemstone identification, it can efficiently used in gemstone grading. Talking about their transparency, Powellite is Transparent while Powellite is Transparent in appearance.