sentences:  After dehydroxylation (and dehydration), generally above 250 °C, geopolymers become more and more crystalline (right in the picture) and above 500-1000 °C (depending on the nature of the alkali cation present) crystallise and have X-ray diffraction patterns and framework structures identical to their geological analogues.There exist a wide variety of potential and existing applications.Some of the geopolymer applications are still in development whereas others are already industrialized and commercialized.