MgSO4

Magnesium sulfate, with the chemical formula MgSO4, is an inorganic salt composed of Mg2+ and SO4 2-. It forms several hydrates; the most common is the heptahydrate MgSO4·7H2O, widely sold as Epsom salt. The anhydrous form is a white crystalline solid.

Natural occurrences include the evaporite minerals epsomite (MgSO4·7H2O), kieserite (MgSO4·H2O), and starkeyite (MgSO4·4H2O). These minerals are found in saline lakes and sedimentary deposits, while seawater brines are major industrial sources of magnesium sulfate.

Magnesium sulfate is highly soluble in water and forms mildly acidic solutions. It is hygroscopic and readily absorbs moisture from the air. In laboratories, the anhydrous form is frequently used as a drying agent for solvents and gases.

Medical use includes magnesium supplementation for deficiency and as an anticonvulsant in obstetrics to prevent seizures in eclampsia. It can be given orally as a laxative and, in some regimens, used to help delay preterm labor (tocolysis). In agriculture, it corrects magnesium deficiency in soils.

Industrial production typically involves reacting sulfuric acid with magnesium oxide or carbonate, yielding MgSO4 and water. Magnesium sulfate is also recovered from brines and evaporite deposits. It serves as a precursor for other magnesium compounds and as a laboratory reagent.

Safety: magnesium sulfate is of moderate toxicity with low volatility. Ingestion in large amounts can cause diarrhea, electrolyte imbalance, and cardiac effects. Inhalation of dust should be avoided. Proper handling, use of personal protective equipment, and adherence to regulatory guidelines are recommended.