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Sillimanite
Sillimanite

Almandine
Almandine



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Sillimanite
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Almandine

Sillimanite and Almandine Optical Properties

Optical Properties

Luster

Vitreous, Subadamantine, Silky
Greasy, Vitreous

Pleochroism

Colourless to pale brown to yellow
None

Dispersion

0.020.03
0.005 1
👆🏻

Transparency

Transparent, Translucent
-

Refractive Index

1.653-1.6851.770-1.820
1 3.25
👆🏻

Optic Character

-
-

Crystal System

Orthorhombic
cubic

Birefringence

0.020-0.022-9999
0 0.296
👆🏻

Clarity

Transparent
TransparentUlrich Henn and Claudio C. Milisenda

Sillimanite and Almandine Optic Character

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

Sillimanite and Almandine Transparency

Similar to their colors, Sillimanite and Almandine 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, Sillimanite is Transparent and Translucent while Sillimanite is Transparent and Translucent in appearance.