Andalusite and Bertrandite Optical Properties

Andalusite

Bertrandite

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1 Optical Properties

1.1 Luster

Vitreous, Greasy

Vitreous

1.2 Pleochroism

strongly trichroic

none.

1.3 Dispersion

0.02NA

0.007 1

1.4 Transparency

Transparent, Translucent

TransparentAnthony et al, Handbook of mineralogy (2001)

1.5 Refractive Index

1.627-1.6501.583-1.614

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

Orthorhombic Pyramidal H-M Symbol (mm2) Space Group: Ccm21

1.8 Birefringence

0.009-0.010Not Available

0 0.296

1.9 Clarity

Transparent

TransparentAnthony et al

Andalusite and Bertrandite Optic Character

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

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Andalusite and Bertrandite Transparency

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