Formula : Na2SiF6
It is colorless hexagonal, odorless and tasteless crystal with relative density 2.679. It is hygroscopic. It is soluble in ether, insoluble in alcohol. The solubility in acid is greater than in water.
It decomposes in alkaline solution and produces sodium fluoride and silicon dioxide. It is decomposed to sodium fluoride and silicon tetrafluoride by heating to 300'C. It is noxious !
It is used as antiseptic in timber industry, hygroscopic agent of acid-resisting concrete, solidifying agent in natural latex products, additive in plating with zinc, nickel, iron and filler in plastic and fluorinating agent in pharmaceuticals and drinking water. It is used to produce insecticide in pesticide industry and sodium fluoride in man-made cryolite.