Rates of dissolution of a natural barite single crystal mounted in a rotating disc have been found to be proportional to the square of undersaturation in terms of concentration, depressed by added common ion, enhanced by foreign bivalent metal ions and unaffected by monovalent ions.

Activation energies for dissolution of barium sulphate microcrystals of three types show variation from 20 to 80kJ mol^–1 and are inversely correlated with energies of dissolution calculated from kinetic solubilities, these energies varying from ΔH° to near zero.

Monte Carlo simulation of dissolution of crystals with stress fields such as would arise from screw, edge and plane dislocations and from edges and apices gave a corresponding variation of simulated activation energy, depending on the degree of stress and on the initial configuration of the surface.

Effects of foreign ions were simulated by introducing next-neighbour repulsions in the Monte Carlo treatment of adsorption on an initially flat surface with a 4 × 4 columnar hole.