Cryolite Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Cryolite

Cut cryolite is somewhat translucent, and has a “sleepy” look. The cuttable material has a very low birefringence, is colorless, and very soft—not exactly an exciting-looking gem. However, there are very few cut stones in existence because of the extreme scarcity of suitable rough. In addition, cryolite is only found abundantly at one locality (Ivigtut).

Cryolite Information

Data Value
Name Cryolite
Colors Colorless, white, brownish, reddish; rarely gray to black.
Hardness 2.5
Fracture Uneven
Cleavage None
Stone Sizes Large cabochons could be cut from the abundant material in Greenland. Facetable material is quite rare, however, and only tiny gems can be obtained.
Formula Na3AlF6.
Crystallography Monoclinic. Crystals cuboidal and prismatic; usually massive.
Refractive Index 1.338-1.339
Birefringence 0.001; almost isotropic.
Dispersion 0.024 (approximately)
Luminescence None observed.
Luminescence Present No
Absorption Spectrum Not diagnostic.
Pleochroism None
Optics a = 1.338; β = 1.338; γ = 1.339. Biaxial (+), 2= 43°.
Optic Sign Biaxial +
Luster Vitreous to greasy.
Specific Gravity 2.97
Transparency Translucent.

Optics:  a = 1.338; β = 1.338; γ = 1.339.

Biaxial (+), 2V= 43°.

Occurrence: Occurs in alkalic rocks at Ivigtut, Greenland.

Also Spain; USSR; Colorado (small amounts).

Comments: Cut cryolite is somewhat translucent, and has a “sleepy” look. The cuttable material has a very low birefringence, is colorless, and very soft—not exactly an exciting-looking gem. However, there are very few cut stones in existence because of the extreme scarcity of suitable rough. In addition, cryolite is only found abundantly at one locality (Ivigtut).

Name: From the Greek kryos (frost) and lithos (stone), hence ice-stone, in allusion to its appearance.

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