Gas Release from Minerals

Quite generally, volatiles are released from minerals during heat treatment in high vacuum conditions. Well known is the gas release during the decomposition of hydrates, hydroxides, carbonates, less so is the release of sulphur species by the decomposition of sulfates, sulfites and sulfides. Oxygen released during the thermal treatment of oxides with polyvalent cations. Most interest is the charge transfer between Fe2+ and Fe3+ in oxides and silicates and the formation of volatile oxygen. The thermal stability of halogenides in crystalline structures is strongly determined by the water presence. The decomposition of complex silicates and borates with halogen anions in the crystal structure is especially of interest.