Natural Zeolite Crystal Chemistry: Structural Diversity and Behavior Under Non-ambient Conditions

Zeolites have remarkable structural and chemical versatility, arising from their wide range of framework configurations, the variable populations of extra-framework species occupying their structural voids, and their ability to adsorb molecular species. These characteristics underpin unique properties like cation exchange, molecular sieving, selective adsorption, and catalytic behavior. Their framework flexibility allows dynamic responses to environmental stimuli, including temperature, pressure, and relative humidity, leading to phenomena such as negative thermal expansion (contraction), amorphization, and dehydration. Under pressure, zeolites can undergo pressure-induced incorporation of ions and molecules from surrounding fluids, modifying their structure and properties. Understanding these responses opens new pathways for tailoring zeolite behavior for technological applications and deepening our comprehension of their role in geological processes.