Covellite and Sillimanite Optical Properties

Covellite

Sillimanite

Add ⊕

1 Optical Properties

1.1 Luster

Resinous

Vitreous, Subadamantine, Silky

1.2 Pleochroism

Marked

Colourless to pale brown to yellow

1.3 Dispersion

NANA

0.007 1

1.4 Transparency

OpaqueAnthony et al, Handbook of mineralogy (2001) More from other references

Transparent, Translucent

1.5 Refractive Index

1.45-2.621.653-1.685

1 3.25

1.6 Optic Character

Not Available

1.7 Crystal System

Hexagonal

Orthorhombic

1.8 Birefringence

Not Available0.020-0.022

0 0.296

1.9 Clarity

OpaqueAnthony et al

Transparent

Covellite and Sillimanite Optic Character

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

Compare Blue Gemstones

Covellite Vs Fluorapatite

Covellite Vs Elbaite

Covellite Vs Falcons Eye

Covellite and Sillimanite Transparency

Similar to their colors, Covellite 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, Covellite is Handbook of mineralogy (2001) More from other references and OpaqueAnthony et al while Covellite is Handbook of mineralogy (2001) More from other references and OpaqueAnthony et al in appearance.