The Mg0-Mn203-Mn0 system in air exhibits two series of solid solutions, (Mg,Mn)Mn204 and (Mg,Mn)O, the boundaries of which have been located. At 1600 +5' C a tie-triangle exists in which these two solid solution phases and a liquid phase coexist with the gas phase. The Mn3+/Mn2+ ratio of the crystalline phases is lowered by the addition of CaSi03 and this has the effect of stabilising the (Mg,M...
