Atacamite and Sillimanite Optical Properties

Atacamite

Sillimanite

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1 Optical Properties

1.1 Luster

Adamantine, Vitreous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

X = pale green; Y = yellow-green; Z = grass-green

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

Not Available

Transparent, Translucent

1.5 Refractive Index

1.8311.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Orthorhombic

1.8 Birefringence

0.0490.020-0.022

0 0.296

1.9 Clarity

Not Available

Transparent

Atacamite and Sillimanite Optic Character

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

Similar to their colors, Atacamite and Sillimanite 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, Atacamite is Not Available while Atacamite is Not Available in appearance.