Because of its importance in the fields of environmental and mineral engineering, study of metal ion adsorption on silicate minerals has received extensive continuing interest. However, limited work has been done to compare the behavior of silicates that are hydrophilic with those that are naturally hydrophobic. Our investigation was undertaken to provide a better understanding of the effect of hydrophobicity and surface heterogeneity on the adsorption of hydrolyzable metal ions (Pb and Cd) at the solid/liquid interface. Concurrent measurements of zeta potentials, the extent of the adsorption, and suspension stability were conducted on colloidal suspensions of two silicate minerals, namely naturally hydrophilic quartz and hydrophobic talc.