Anhydrous, it is a white crystalline solid of formula Na2SO4 known as the mineral thenardite; the decahydrate Na2SO4•10H2O has been known as Glauber's salt or, historically, sal mirabilis since the 17th century. With an annual production of 6 million tonnes, it is one of the world's major commodity chemicals. 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.