What is sodium sulphate?

Sodium sulfate is the sodium salt of sulfuric acid. When anhydrous, it is a white crystalline solid of formula Na2SO4 known as the mineral thenardite. The decahydrate, Na2SO4·10H2O, is known as Glauber’s salt. Sodium sulfate is mainly used for the manufacture of detergents and in the Kraft process of paper pulping, though it has many other uses. About half of the world’s production is from the natural mineral form of the decahydrate (mirabilite), and half from by-products of chemical processes.