A combined quaternary ammonium salt was used as a collector for the flotation of quartz. It shows better selectivity and collectability than dodecyl amine chloride and cetyl trimethylammonium bromide for the flotation of quartz from magnetite and specularite, but the quebracho should be used in the flotation separation of quartz from specularite. By the measurement of zeta potentials, contact angles, and adsorption of the combined quateman, ammonium salt the results show that the combined quaternary ammonium salt is preferred to adsorb on the surface of quartz, changes its zeta potentials and contact angles, and increases its hydrophobicity. The results of FTIR show that the combined quaternary ammonium salt adsorbs on the quartz surface in physical adsorption with no new products. (c) 2005 Elsevier B.V. All rights reserved.