[en] Radioactive sand stone samples of sedimentary rocks constitute fine particles like clays, hydrous iron oxides (goethite) and humic acid. All these colloidal particles have the property of sorption, ion-exchange etc. under suitable conditions. Hence the ability of these fine particles for uranium sorption and retention has been investigated in detail individually on ferric hydroxide gel, goethite and humic acid gel and the thermoanalytical studies were also carried out. Freshly precipitated ferric hydroxide gel exhibited uranyl sorption upto 9%. Natural and synthetic goethite showed upto 2.8%, and humic acid upto 6% under optimum conditions of pH and uranyl concentration. Differential thermal analysis was carried out to characterise ferric hydroxide gel, natural and synthetic goethite and humic acid gel. (author)