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Sillimanite
Sillimanite

Corundum
Corundum



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Sillimanite
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Corundum

Sillimanite and Corundum Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Adamantine, Vitreous
1.2 Pleochroism
Colourless to pale brown to yellow
None
1.3 Dispersion
NA0.02
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Transparent, Translucent
1.5 Refractive Index
1.653-1.6851.758-1.780
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
Trigonal
1.8 Birefringence
0.020-0.0220.007-0.010
Achroite
0 0.296
1.9 Clarity
Transparent
Gemmological Tables (2004) More from other references

Sillimanite and Corundum Optic Character

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

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