Magnesium sulfate constituents of evaporitic potassium-magnesium (K-Mg) salts deposits. Bright spots observed by the Dawn Spacecraft in Occator Crater on the dwarf planet Ceres are most consistent with reflected light from magnesium sulfate hexahydrate. Almost all known mineralogical forms of MgSO are hydrates. Epsomite is the natural analogue of "Epsom salt". Another heptahydrate, the copper-containing mineral alpersite (Mg,Cu)SO·7HO, was recently recognized. Both are, however, not the highest known hydrates of MgSO, due to the recent terrestrial find of meridianiite, MgSO·11HO, which is thought to also occur on Mars. Hexahydrite is the next lower (6) hydrate. Three next lower hydrates—pentahydrite, starkeyite, and especially
Magnesium hydroxide formation of expansive brucite. This reaction, one of the two main alkali-aggregate reaction (AAR) is also known as alkali-carbonate reaction. Magnesium hydroxide Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH). It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk of magnesia, as well as laxatives. Combining a solution of many magnesium salts with alkaline water induces precipitation of solid Mg(OH): On a commercial scale, Mg(OH) is produced by treating seawater with lime (Ca(OH)). 600m of seawater