Magnesium oxide

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A fine, white powdery compound that occurs naturally as the mineral periclase. Magnesium oxide is a highly refractive material that is most often used to manufacture crucibles, ceramic glazes, glass, fire brick, and magnesia cement. It was tried as an Abrasive for polishing silver by Wharton et al. (1990) but gave poor results and is not recommended. Magnesium oxide has also been used as a non aqueous Alkalization agent for paper.

Synonyms and Related Terms

magnesia; magnesian earth; Maglite; Bookkeeper; periclase; calcined brucite


  • Noncombustible.
  • Toxic by inhalation of fumes.
  • ThermoFisher: SDS

Physical and Chemical Properties

Soluble in acids and ammonium salt solutions. Slightly soluble in water (reacts to form magnesium hydroxide).

Composition MgO
CAS 1309-48-4
Melting Point 2800 C
Density 3.6 g/ml
Molecular Weight mol. wt. = 40.32
Boiling Point 3600 C

Resources and Citations

  • G.Wharton, S.Lansing, W.Ginell, "A Comparative Study of Silver Cleaning Abrasives" JAIC 29:13-31, 1990. LINK
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 5713