Polarised light micrograph of crystals of magnesium sulphate. Magnesium sulphate may be produced by the action of sulphuric acid on magnesium carbonate, and occurs naturally as kieserite or reichardite. In its hydrated form (MgSO4. 7H2O) it is known as Epsom Salts, and is used as a purgative. Magnesium sulphate also has uses in the textile industry, being used as a dressing for cotton goods and as a dyeing agent. Magnification: x45 at 6x7cm size.