MuhdarinaA.Wahab, MohammadSyaiful, Bahri2014-11-092014-11-092014-11-091907-0500Dodyhttp://repository.unri.ac.id/xmlui/handle/123456789/6508Natural clay from Desa Cengar in Riau Province has been taken as an experimental focus. The natural clay which consist of kaolinite, muscovite and quartz were modified in chloride acid, acetic acid, and salts of ammonium chloride and ammonium acetic, exactly in 1 molar aqueous solution by mixing it there, respectively. The modified clay, then, were characterized the physicochemical is change of mineral identities, chemical composition, Si/Al ratio, exchangeable cation capacity and specific surface area. The modifying processes don’t change their mineral content and Si/Al ratio, but some of Ca and Mg cations have been exposure from surfaces of natural clay, while the change of specific surface area of the modified clay have been varied. Ammonium chloride salt modifier with the highest decationization action and the other one, ammonium acetic salt have increased the specific surface area of natural clay. Keywords: Cengar natural clay, physicochemical, modifying process, decationizationclayCengarUR-Proceedings