THE NATURE OF CLAY VOLATILES AND CONDENSATES AND THE EFFECT ON THEIR ENVIRONMENT - A REVIEW

When clays are heated, a mass loss occurs due to the evolution of vola tiles. Most of these are water vapour, but in addition minor amounts o f a complex assemblage of other species are liberated. The correspondi ng condensates are colloidal suspensions. The composition of the volat iles and condensates and the release patterns of the gases are reviewe d. The nature of the assemblages varies from one clay to another and d epends on the thermal regime. Both volatiles and condensates are very reactive. Their reactivity persists even after prolonged storage. They act as acid catalysts in reactions with organic matter and decompose calcite and other carbonates. Condensates were found to etch the surfa ces of quartz crystals and to dealuminate and partly destroy an Al-ric h faujasite (zeolite). Possible implications of reactions of clay vola tiles and condensates for natural processes are discussed.