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Sillimanite
Sillimanite

Bertrandite
Bertrandite



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Sillimanite
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Bertrandite

Sillimanite and Bertrandite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Vitreous
1.2 Pleochroism
Colourless to pale brown to yellow
none.
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
TransparentAnthony et al, Handbook of mineralogy (2001)
1.5 Refractive Index
1.653-1.6851.583-1.614
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21
1.8 Birefringence
0.020-0.022Not Available
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentAnthony et al

Sillimanite and Bertrandite Optic Character

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

Similar to their colors, Sillimanite and Bertrandite 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.