Data on the kinetic anion replacement systems calcite-PO 4 (super -3) , calcite-F (super -) , gypsum-CO 3 (super -2) , and gypsum-PO 4 (super -3) are given, along with concomitant Sr (super +2) inclusion into the final product. In a system containing several anions, only the anion forming the least soluble compound with the available cation is stable. The replacement reaction rate is directly proportional to the solubility difference between the original solid and final product. Several other variables also affect the reaction rate including temperature, column flow rate, influent pH, surface area of the initial solid, concentration of extraneous ions, and concentration of active anion. These variables affect diffusion rates to and from reaction sites as well as differences in solubility between initial and final reaction products. The crystal structure of the resulting product greatly affects the concomitant removal rate of Sr (super +2) into the resulting product.