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Sillimanite and Bastnasite Optical Properties


Bastnasite and Sillimanite Optical Properties


Optical Properties

Luster
Vitreous, Subadamantine, Silky   
Vitreous, Greasy, Pearly   

Pleochroism
Colourless to pale brown to yellow   
Faint   

Dispersion
Not Available   
Not Available   

Transparency
Transparent, Translucent   
Gemmological Tables (2004) More from other references   

Refractive Index
1.653-1.685   
1.717-1.722   

Optic Character
Not Available   
Not Available   

Crystal System
Orthorhombic   
Hexagonal   

Birefringence
0.020-0.022   
0.100   

Clarity
Transparent   
TransparentUlrich Henn and Claudio C. Milisenda   

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Sillimanite and Bastnasite Optic Character

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

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Sillimanite and Bastnasite Transparency

Similar to their colors, Sillimanite and Bastnasite 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.

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