E530 - Òxid de magnesi

Magnesium oxide -MgO-, or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium -see also oxide-. It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water -MgO + H2O → Mg-OH-2-, but it can be reversed by heating it to separate moisture. Magnesium oxide was historically known as magnesia alba -literally, the white mineral from magnesia – other sources give magnesia alba as MgCO3-, to differentiate it from magnesia negra, a black mineral containing what is now known as manganese. While "magnesium oxide" normally refers to MgO, magnesium peroxide MgO2 is also known as a compound. According to evolutionary crystal structure prediction, MgO2 is thermodynamically stable at pressures above 116 GPa -gigapascals-, and a semiconducting suboxide Mg3O2 is thermodynamically stable above 500 GPa. Because of its stability, MgO is used as a model system for investigating vibrational properties of crystals. - Viquipèdia