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Sillimanite
Sillimanite

Iolite
Iolite



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Sillimanite
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Iolite

Sillimanite and Iolite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Vitreous
1.2 Pleochroism
Colourless to pale brown to yellow
Not Available
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Transparent, Translucent, Transparent to translucent
1.5 Refractive Index
1.653-1.6851.52-1.56
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
Orthorhombic
1.8 Birefringence
0.020-0.022Not Available
Achroite
0 0.296
1.9 Clarity
Transparent
Transparent to translucent

Sillimanite and Iolite Optic Character

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

Similar to their colors, Sillimanite and Iolite 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.