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Almandine
Almandine

Sillimanite
Sillimanite



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Almandine
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Sillimanite

Almandine and Sillimanite Optical Properties

Optical Properties

Luster

Greasy, Vitreous
Vitreous, Subadamantine, Silky

Pleochroism

None
Colourless to pale brown to yellow

Dispersion

0.030.02
0.005 1
👆🏻

Transparency

-
Transparent, Translucent

Refractive Index

1.770-1.8201.653-1.685
1 3.25
👆🏻

Optic Character

-
-

Crystal System

cubic
Orthorhombic

Birefringence

-99990.020-0.022
0 0.296
👆🏻

Clarity

TransparentUlrich Henn and Claudio C. Milisenda
Transparent

Almandine and Sillimanite Optic Character

Almandine and Sillimanite optical properties play a significant role while distinguishing these gemstones from each other. These properties are influenced by the Almandine 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 Almandine 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.

Almandine and Sillimanite Transparency

Similar to their colors, Almandine 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, Almandine is while Almandine is in appearance.