Anhydrous sodium sulfate

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 found naturally as the mineral mirabilite, and in processed form has been known as Glauber's salt or, historically, sal mirabilis since the 17th century. Another solid is the heptahydrate, which transforms to mirabilite when cooled. With an annual production of 6 million tonnes, it is a major commodity chemical product.
Sodium sulfate is mainly used for the manufacture of detergents and in the Kraft process of paper pulping. About two-thirds of the world's production is from mirabilite, the natural mineral form of the decahydrate, and the remainder from by-products of chemical processes such as hydrochloric acid production.
Anhydrous sodium sulfate is widely used in the manufacture of sodium sulfide, sodium silicate etc.; also used in the making of sulphate pulping the paper making industry; as filler in dyeing industry; as dyeing auxiliary in printing & dyeing industry; also used in synthetic fibers, leather making, enamel and soaps etc.