Sodium Selenite is a colourless solid. The pentahydrate Na₂SeO₃H₂O₅ is the most common water-soluble selenium compound.
anhydrous salt is used in the production of some glass. Although the selenates are much more toxic, many physical properties of sodium selenate and sodium sulfate are similar.
One of the earliest applications of sodium selenate was in the glass industry. Selenium produces a red hue in glass.