Abstract: The tuffs of Neogene basin around the Gördes Region have high content of zeolite about 2/3 magnituteof their volume and contain less or not in some zones. Zeolite mineral type is clinoptilolite in the lower tuffs and heulandite is present in the upper tuffs. This difference is seen clearly on the whole rock chemistry of two tuff units. The geochemical relations between chemical elements and the quantity of zeolitization were examined and it is found thatall the major chemical elements are mobile. Some elements were been liberated from fresh glasses and used again for zeolitization or other alterations in the same system. Although, some of the major elements may have come from out ofthe system. Lossing of SiO2, Na ^ and K^O, and gaining of A12O3, MgO, CaO and HgO have been determined whenwe compared unaltereted rock with zeolite - rich rock. These changes show more increasing in both the loss and gain inthe heulandite alteration than in the clinoptilolite alteration.