In general, selenate salts resemble sulfate salts, but are more soluble. One of the earliest applications of sodium selenate was in the glass industry. Minerals that are pure selenide or selenate compounds are known but rare. Another method is the reaction of liquid sulfur trioxide with potassium selenate. Sodium selenate and selenite are also common in premix animal feed. SeO. Oxidation of this anion gives sodium selenate, NaSeO. For this purpose, various selenite and selenate salts are added. Chronic exposure to sodium selenate can cause severe lung, kidney, and liver damage. In strongly acidic conditions, the hydrogen selenate ion, , is formed. Selenate and other forms of selenium are highest in areas where ancient seas have evaporated. Sodium selenate is also used as a decolorizing agent in glass production. A diammonium dicadmium selenate langbeinite could not be crystallised from water, but a trihydrate exists. Many selenate salts have the same crystal structure as the corresponding sulfate salts. Sodium selenate is a common ingredient in some insecticides used against mites, aphids, and mealybugs. Sodium selenate is produced by oxidation of selenium, first with nitric acid, producing selenous acid.