Magnesium Hexafluorosilicate
Like several related compounds, hexafluorosilicic acid does not exist as a discrete species, that is, a material with the formula H2SiF6 has not been isolated. Acids described similarly include chloroplatinic acid, fluoroboric acid, and hexafluorophosphoric acid, and, more commonly, carbonic acid.
Sodium Hexafluorosilicate
Sodium fluorosilicate is a compound with formula Na2SiF6.