Entry 1 sense Webster, 1913 Ralstonite /(ra̤l"stŭn*īt)/ · Ral·ston·ite · IPA 01 n. A fluoride of alumina and soda occurring with the Greenland cryolite in octahedral crystals. 1. A fluoride of alumina and soda occurring with the Greenland cryolite in octahedral crystals.(Min.)