Cryolite

Cryolite is a rare sodium aluminium fluoride mineral with the formula Na₃AlF₆. It was historically mined in Greenland and is used as a flux in aluminium production.

Hall–Héroult process: An industrial process that produces aluminium by electrolysing alumina dissolved in molten cryolite-based electrolyte. Cryolite is the principal solvent in the process’s molten electrolyte.
Electrolytic reduction: The use of electrical energy to drive a chemical reduction that would not proceed spontaneously. The Hall–Héroult process reduces dissolved aluminium ions by this method.
Ivittuut: A settlement in southwestern Greenland beside the historic major natural cryolite deposit. The mine at Ivittuut supplied most commercially important natural cryolite.
Sodium: A soft, highly reactive chemical element with symbol Na and atomic number 11. Three sodium ions balance the charge of the aluminium-fluoride framework in cryolite.
Aluminium smelting: The extraction of metallic aluminium from aluminium-bearing compounds, chiefly by electrolysis. Cryolite makes the dominant electrolytic method for smelting aluminium practical.
Electrolyte: A substance that conducts electricity through mobile ions when molten or dissolved. Molten cryolite carries ions between the electrodes during aluminium electrolysis.
Cryolite mine: A historic mine at Ivittuut, Greenland, worked primarily for its unusually abundant cryolite deposit. Its extraction turned a rare mineral into a strategic industrial commodity.
Aluminium: A lightweight, corrosion-resistant chemical element with symbol Al and atomic number 13. One aluminium ion is part of each formula unit of cryolite.
Alumina: Aluminium oxide, Al₂O₃, the principal feedstock for primary aluminium production. Alumina dissolves in molten cryolite instead of requiring electrolysis as a pure melt.
Melting point depression: The lowering of a substance’s melting temperature when another substance is dissolved in it. Dissolving alumina in cryolite-based melts avoids the much higher temperature needed to melt pure alumina.

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