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The Collaborative International Dictionary
Ralstonite

Ralstonite \Ral"ston*ite\ (r[add]l"st[u^]n*[imac]t), n. [So named after J. G. Ralston of Norristown, Penn.] (Min.) A fluoride of alumina and soda occurring with the Greenland cryolite in octahedral crystals.

Wiktionary
ralstonite

n. (context mineralogy English) An isometric-hexoctahedral mineral containing aluminum, fluorine, hydrogen, magnesium, oxygen, and sodium.