The specific affinity of iron minerals for starch has been successfully exploited in the selective flocculation and flotation of iron ores. The same phenomenon complicates the flotation separation between iron oxides, i.e., magnetite and Fe-Mg-Al-bearing silicates. Adsorption isotherms were constructed, and the mechanisms of the adsorption of starch on quartz, magnetite and Fe-Mg-Al-bearing amphibole pargasite were discussed in this paper. The nature of the species adsorbed on minerals was determined by DRIFT and XPS spectroscopy. The flotation behaviour of magnetite and silicates at pH 10 upon stirring in a starch solution was demonstrated. The adsorption and DRIFT study results concluded that starch is adsorbed both on quartz and amphiboles. However, the starch adsorption mechanism based on the chemical complexation is proposed to explain the strong depression effect of the starch during the magnetite and Fe-Mg-Al-bearing amphibole flotation with an amine compared with quartz. (C) 2013 Elsevier B.V. All rights reserved.