Magnesia is a term used to describe various products from magnesium-rich sources. Magnesium makes up two percent of the earth's crust and is the eighth most plentiful element. It also is the third most abundant element found in sea water. The two most important magnesium minerals are magnesite (MgCO3 ) and brucite (Mg(OH)2). Magnesite is the most common source of magnesia and serves many important industrial applications. Magnesia either is produced from magnesite ore or extracted from seawater or brines as magnesium hydroxide.
Magnesia is produced in three forms: caustic calcined (CCM), dead burned (DBM) and fused (FM). The latter two are largely used in the production of refractories. DBM and FM grades are typically used in basic refractories in combination with graphite, dolomite, alumina, or chrome.Magnesia is generally derived from the calcination of magnesite, although higher-purity synthetic magnesia can be produced from seawater or brine sources.