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Andalusite
Andalusite

Petalite
Petalite



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Andalusite
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Petalite

Andalusite and Petalite Optical Properties

1 Optical Properties
1.1 Luster
Vitreous, Greasy
Vitreous, Pearly
1.2 Pleochroism
strongly trichroic
AbsentWalter Schumann
1.3 Dispersion
0.020.01
Fluorite Optical Properties
0.007 1
1.4 Transparency
Transparent, Translucent
Gemmological Tables (2004) More from other references
1.5 Refractive Index
1.627-1.6501.502-1.523
Agate Opal
1 3.25
1.6 Optic Character
Not Available
Not Available
1.7 Crystal System
Orthorhombic
monoclinic
1.8 Birefringence
0.009-0.0100.012-0.016
Achroite
0 0.296
1.9 Clarity
Transparent
TransparentUlrich Henn and Claudio C. Milisenda

Andalusite and Petalite Optic Character

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

Andalusite and Petalite Transparency

Similar to their colors, Andalusite and Petalite 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, Andalusite is Translucent and Transparent while Andalusite is Translucent and Transparent in appearance.