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 remove moisture. Magnesium oxide was historically known as magnesia alba (literally, the white mineral from Magnesia), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese. Related oxides
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. Electric properties
Pure MgO is not conductive and has a high resistance to electric current at room temperature. The pure powder of MgO has a relative permettivity inbetween 3.2 to 9.9 
  
    
      
        k
      
    
    {\displaystyle k}
   with an approximate dielectric loss of tan(δ) > 2.16x103 at 1kHz. Production
Magnesium oxide is produced by the calcination of magnesium carbonate or magnesium hydroxide.
Gas Mantles
Most Gas Mantles utilize Magnesium Oxide. Early Iterations such as the Clamond basket used only this. Later versions use ~60% Magnesium oxide, with other components such as Lanthanum oxide or Yttrium oxide making up the rest. Another exception would be Thoriated gas mantles. Niche uses
MgO is one of the components in Portland cement in dry process plants. Magnesium oxide is used extensively in the soil and groundwater remediation, wastewater treatment, drinking water treatment, air emissions treatment, and waste treatment industries for its acid buffering capacity and related effectiveness in stabilizing dissolved heavy metal species.Many heavy metals species, such as lead and cadmium are most soluble in water at acidic pH (below 6) as well as high pH (above 11). Solubility of metals affects bioavailability of the species and mobility soil and groundwater systems. Most metal species are toxic to humans at certain concentrations, therefore it is imperative to minimize metal bioavailability and mobility. Granular MgO is often blended into metals-contaminated soil or waste material, which is also commonly of a low pH (acidic), in order to drive the pH into the 8–10 range where most metals are at their lowest solubilities (basic). Metal-hydroxide complexes have a tendency to precipitate out of aqueous solution in the pH range of 8–10. MgO is widely regarded as the most effective metals stabilization compound when compared to Portland cement, lime, kiln dust products, power generation waste products, and various proprietary products due to MgOs superior buffering capacity, cost effectiveness, and ease/safety of handling.