Froth flotation of high-iron marmatite particles activated by ammoniacal copper(II) solution has been studied in this work. This study was performed on single marmatite mineral of 76-125 mu m in size and 20% iron content by using micro-flotation. The results have shown that ammoniacal copper(II) solution effectively activated high-iron marmatite particles in the flotation with xanthate as the collector, being much better than copper sulfate, a traditional activator for sphalerite and marmatite flotation. Also, the maximum activation by ammoniacal copper(II) solution in the flotation appeared around pH 9, compared with pH 13-14 by copper sulfate. Therefore, the substitution of ammoniacal copper(II) solution for copper sulfate in high-iron marmatite flotation would increase the separation efficiency and would allow large savings on the consumptions of time and xanthate. Based on the species distribution diagram for copper(II)-ammonia system, it has been found that the activation of ammoniacal copper(II) solution in high-iron marmatite flotation might be originated from copper(II)-ammonia complexes, CuNH32+ and Cu(NH3)(2)(2+), through the adsorption on the mineral surface. (C) 2006 Elsevier Ltd. All rights reserved.