The X-ray diffraction patterns of the chabazite sample before and after the conditioning process are shown in Fig. 1. Both pat-terns contain crystalline forms of chabazite-Ca (JCPDS #034–0137) and clinoptilolite-Ca (JCPDS #039–1383). Most of the peaks correspond to hexagonal chabazite-Ca, Ca2Al4Si8O24 12H2O. A clear increase in peak intensity is observed in the pattern of the condi-tioned chabazite sample relative to the unconditioned sample, showing that the conditioning process results in an increase in the crystallinity of the natural zeolite. This increased crystallinity can be associated with modifications in the amount and position of the extra framework species in the zeolite cavities after the