Abstract: The progressive reconstitution of the thermally decomposed members of the kaolin group (the so-called “meta” phases) has been studied as a function of time, temperature and water vapor pressure of reconstitution, with a view to determining the extent of “pseudomorphism” after the parent structure. The nature of the dehydroxylated dickite which shows a 14A reflection has been investigated further but no additional x-ray data characteristic of a 14A-type structure can be found.
The sequence of rehydration shows that all the meta phases tend to form kaolinite, but the actual sequence of events depends on the parent material. Under the proper conditions well-crystallized kaolinite is obtained from all the meta phases. However, the original minerals themselves could not be converted directly to kaolinite within the time limits of the experiments.