Borax Decahydrate, also known as Sodium Tetraborate Decahydrate or simply Borax, is a naturally occurring compound used widely in detergents and cleaning agents. A salt of boric acid, its typical form is a white powder consisting of soft water-soluble crystals. Its anti-fungal properties make it useful in treating certain skin conditions, and it is also used in pest control applications. Borax has several industrial applications as well, including use as a flux to eliminate undesired metal oxides and use in flame retardants.