Sodium Sulfate, Anhydrous is chemically very stable, and is unreactive toward most oxidizing or reducing agents at normal temperatures. It is a neutral salt and will form aqueous solutions with a ph of ~7. Anhydrous sodium sulfate occurs in arid environments as the mineral thenardite; however the decahydrate (sc-203405) is the most abundant natural form and is derived from the mineral, mirabilite, often found in lake beds. Anhydrous sodium sulfate is used in the laboratory as an inert drying agent for removing traces of water from organic solutions. It is only effective below 30°C, but is fairly inert and can be used with a variety of materials.