Magnesium oxide (MgO) varies in reactivity according to the temperature at which it has been produced.
- Natural magnesite is the raw material used, most commonly for industrial grades of magnesium oxide.
Magnesite (MgC03) can be calcined to produce highly reactive magnesium oxide which is generally known as caustic calcined magnesite (CCM). - At higher temperatures the resultant magnesium oxide is considerably less reactive and colloquially known as dead burned magnesite (DBM).
- Electric arc furnaces producing very high temperatures to melt the magnesite create fused magnesite or fused magnesia.
- Another source of magnesium carbonate is sea water brine, from which the magnesium salts are precipitated and then calcined to produce light magnesium oxide.