A model is developed that calculates the chemical equilibrium that exists between a flowing electrolyte solution and mineral assemblages. The development computes the mineral and aqueous compositions as a function of time and position in a one-dimensional porous medium. The model considers the dissolution of solids as well as their precipitation. The application of the model to various problems has revealed that characteristic aqueous and solid phase concentration waves develop and propagate through the system in a chromatographic manner. Example calculations are presented that illustrate the widespread applicability of the model. Specifically, a calculation is presented that reproduces the genetic mineralization features that are found in sandstone-type uranium deposits.