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.
M 0184 (OTTO) Magnesuim oxide, 99.999% Cas 1039-48-4 - used in medicine, colorimetry, industrial cables, heating elements, ceramics, spin-tunneling devices, and several other materials.