Thulite and Petalite Optical Properties

Thulite

Petalite

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1 Optical Properties

1.1 Luster

Vitreous

Vitreous, Pearly

1.2 Pleochroism

Present

AbsentWalter Schumann

1.3 Dispersion

NA0.01

0.007 1

1.4 Transparency

Opaque, Translucent, Opaque . May be translucent in thin backlit sections.

Gemmological Tables (2004) More from other references

1.5 Refractive Index

1.6951.502-1.523

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

monoclinic

1.8 Birefringence

0.006-0.0180.012-0.016

0 0.296

1.9 Clarity

OpaqueHerve Nicolas Lazzarelli

TransparentUlrich Henn and Claudio C. Milisenda

Thulite and Petalite Optic Character

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

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Thulite and Petalite Transparency

Similar to their colors, Thulite 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, Thulite is Opaque, Opaque . May be translucent in thin backlit sections. and Translucent while Thulite is Opaque, Opaque . May be translucent in thin backlit sections. and Translucent in appearance.