Cryolite (Na3[AlF6], sodium hexafluoroaluminate) is a mineral with an unusual use: as the molten salt it is used as a solvent for aluminium oxides in the electrolytic refining of aluminium from its ores. The nature of the liquid phase is controversial with [AlF6]3-, [AlF5]2-, [AlF4]- and F- ions claimed to be present. The solid state has been much less studied. In principle, the low symmetry found in the low temperature phase, should remove all degeneracies and allow all the modes to be observed. However, only the Raman modes and the infrared active bending mode have been observed and there is no information on the whole body motions. The aim of this proposal is to observe all of the modes of cryolite by a simultaneous combination of Raman and INS spectroscopies.