Cryolite is commonly associated with the industrial electrolysis of alumina to obtain aluminum (Hall-Héroult process): addition of cryolite lowers the production cost by lowering alumina's melting point by over 1,000 degrees. Cryolite is a rare mineral, whose name is derived from the Greek words for frost or ice and stone, referring to the allusion of its frozen-water appearance (mindat.org/min-1161).
Cryolite is mainly composed of sodium hexafluoroaluminate: Na3[AlF6]. Commercial mining of a huge deposit of this mineral started in the late 1850s near the town of Ivittuut in southwest Greenland (Kalaallit Nunaat, meaning “Land of the Kalaallit people”). Cryolite and its mining site is depicted in a stamp issued in Greenland on October 19, 2009 [1,2]: Aatsitassanik ilisimatuutut misissuineq, kryolit, Mineralforskning, kryolit.
Link and reference to Kalaallit Nunaat's cryolite stamp
[1] http://www.geostamps.eu/res/G/2764gro09.jpg.
[2] Daniel Rabinovich: The Stone that Came in from the Cold. Chemistry International September-October 2010, page 33.
Monday, October 11, 2010
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