An impact test apparatus can be used to determine particle interfacial energies with varying relative air humidity. It was observed that capillary condensation increased the adhesive forces of hydrophilic materials. A systems humidity separation window was identified and the differences in interfacial energy for a hydrophilic surface and for a hydrophobic surface can be exploited in order to achieve the separation of particles. Separation and concentration of particles, particularly particles within a mineral ore body, can be obtained.