Abstract: Part of the research on the structure, synthesis, and properties of clay minerals in Yugoslavia is reviewed with particular reference to the following problems: (a) attempts to synthesize halloysite from solutions under normal conditions; (b) structure and properties of synthetic montmorillonites; (c) dehydroxylation of kaolin minerals under nonequilibrium conditions; (d) structural properties of metakaolin as shown by adsorption of colloidal gold; and (e) free silica in bentonites.