Cryolite
A variety of Minerals
What is Cryolite?
Cryolite (Na3AlF6, sodium hexafluoroaluminate) is an uncommon mineral identified with the once-large deposit at Ivittuut on the west coast of Greenland, depleted by 1987.
Uses & Applications
Molten cryolite is used as a solvent for aluminium oxide (Al2O3) in the Hall–Héroult process, used in the refining of aluminium. It decreases the melting point of molten (liquid state) aluminium oxide from 2000 to 2500 °C to 900–1000 °C, and increases its conductivity thus making the extraction of aluminium more economical. Cryolite is used as an insecticide and a pesticide. It is also used to give fireworks a yellow color.
Optical Properties
- Refractive Index
- 1.338-1.339
- Birefringence
- 0.001
- Optical Character
- Biaxial positive
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Cryolite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Cryolite Localities Map
See where Cryolite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
The Meaning
In traditional folklore, cryolite was considered a stone of protection. During ancient times, people believed that cryolite warded off evil spirits, so they would wear it around their chests, often set in gold, to deter phantoms and thus protect themselves.
Key Characteristics
Characteristics of Cryolite
Cryolite occurs as glassy, colorless, white-reddish to gray-black prismatic monoclinic crystals. It has a Mohs hardness of 2.5 to 3 and a specific gravity of about 2.95 to 3.0. It is translucent to transparent with a very low refractive index of about 1.34, which is very close to that of water; thus if immersed in water, cryolite becomes essentially invisible.
Quick Facts
Physical Properties
- Color
- Colourless, white, brown, grey, black, colourless in transmitted light
- Hardness (Mohs)
- 2.5
- Density
- 2.973 - 2.9732 g/cm³
- Streak
- White
Chemical Properties
- Chemical Formula
- Na2NaAlF6
- Elements
- Al, F, Na
Also Known As
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Cryolite FAQs
How do I identify Cryolite?
Cryolite can be identified by its hardness of 2.5 on the Mohs scale, Colourless color. Look for these key characteristics when examining specimens.
What color is Cryolite?
Cryolite typically appears in Colourless, white, brown, grey, black, colourless in transmitted light. Color can vary depending on impurities and formation conditions.
How hard is Cryolite?
Cryolite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the characteristics of cryolite of Cryolite?
Cryolite occurs as glassy, colorless, white-reddish to gray-black prismatic monoclinic crystals. It has a Mohs hardness of 2.5 to 3 and a specific gravity of about 2.95 to 3.0. It is translucent to transparent with a very low refractive index of about 1.34, which is very close to that of water; thus if immersed in water, cryolite becomes essentially invisible.
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