in distribution coefficient with ph above about 7 7 5 this is attributed to hydrolysis of am and np which is typical behavior for trivalent actinides sorption studies on granite rocks gave reasonably good agreement between the experimentally determined values of the distribution coefficients of am and np and those calculated from values of the individual components of the granite samples accordingly prediction of distribution coefficients of rock mixtures based on values determined for individual components appears feasible experimental determination of the effect of anions on sorption of actinides indicated that apatite and anhydrite were particularly effective sorbents a combination of naturally occurring minerals has been found which is uniquely suited for sorption of all hazardous nuclides in radioactive wastes the combination of minerals includes quartz montmorillonite phosphate containing mineral such as apatite sulfate mineral such as anhydrite ferrous mineral such as magnetite and clay mineral such as attapulgite it is proposed that the phosphate mineral sorbs the actinides of all valence states by a strong chemisorption reaction the sulfate mineral causes precipitation of the fission products sr and ra as insoluble sulfates the ferrous mineral reduces the higher valent actinides and tco 4 to the more readily sorbed iii and iv valent states and attapulgite sorbs both actinides and cesium it is proposed that rare earth fission products will be sorbed in a manner similar to the trivalent actinides quartz provides thermal and structural stability to the mixture and montmorillonite forms an impervious elastic barrier to water flow and serves as a strong cation exchanger although the specific mechanism by which each mineral sorbs radioactive products.