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Sillimanite
Sillimanite

Phosgenite
Phosgenite



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Sillimanite
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Phosgenite

Sillimanite and Phosgenite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Subadamantine, Silky
Adamantine
1.2 Pleochroism
Colourless to pale brown to yellow
Weakly pleochroic with O reddish and E greenish in thick sections.
1.3 Dispersion
NANA
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Gemmological Tables (2004) More from other references
1.5 Refractive Index
1.653-1.6852.117-2.145
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
tetragonal
1.8 Birefringence
0.020-0.0220.027
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentUlrich Henn and Claudio C. Milisenda

Sillimanite and Phosgenite Optic Character

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

Similar to their colors, Sillimanite and Phosgenite 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.