What is Magnesium sulfate?

Magnesium sulfate or magnesium sulphate (in British English) is a chemical compound, a salt with the formula MgSO4, consisting of magnesium cations Mg²⁺ (20.19% by mass) and sulfate anions SO₂⁻⁴. It is a white crystalline solid, soluble in water but not in ethanol.

Uses

The main use of magnesium sulfate is in agriculture, to correct soils deficient in magnesium (an essential plant nutrient because of the role of magnesium in chlorophyll and photosynthesis). The monohydrate is favored for this use; by the mid 1970s, its production was 2.3 million tons per year.The anhydrous form and several hydrates occur in nature as minerals, and the salt is a significant component of the water from some springs.

Magnesium is a naturally occurring mineral that is important for many systems in the body especially the muscles and nerves. Magnesium sulfate also increases water in the intestines.

Magnesium sulfate is used as a laxative to relieve occasional constipation.

Not all external uses for magnesium sulfate have been approved by the FDA. Epsom salt should not be used in place of medication prescribed for you by your doctor.

Magnesium sulfate may also be used for purposes not listed in this medication guide.

Preparation

Magnesium sulfate is usually obtained directly from dry lake beds and other natural sources. It can also be prepared by reacting magnesite (magnesium carbonate, MgCO3) or magnesia (oxide, MgO) with sulfuric acid.

Another possible method is to treat seawater or magnesium-containing industrial wastes so as to precipitate magnesium hydroxide and react the precipitate with sulfuric acid.