AbstractThe responses of chromite and the gangue minerals olivine and serpentine commonly associated with it to fluoride activation in soap and anine flotation were studied.Hydrofluoric acid was shown to have good selective properties in amine flotation of chromite that qualify it as a possible flotation reagent. It seems that hydrofluoric acid could be adsorbed strongly and preferentially on the chromite surface to give the extremely insoluble CrF2−ion that exhibits great affinity for the positively charged dodecylammonium ion, leading to the formation of water‐repellent coatings. On the other hand, hydrofluoric acid attacks the magnesium and ferrous sites on the surface of olivine and serpentine with the formation of soluble magnesium and ferrous fluorides. Hydrofluoric acid also attacks the silicon sites at pH<4 with the formation of fluosilicic acid, and therefore impedes the formation of collector‐coating on the surface of olivine and serpentine.In contrast, sodium fluosilicate had a detrimental effect on both soap and amine flotation of chromite. This is probable due to its dissociation to SiF62−ions which are probably adsorbed on to cationic sites of chromite and gangue minerals with the formation of the corresponding negatively charged fluosilicates. As a consquence, dodecylammonium ions could be attached to the surface of chromite and gangue minerals, whereas oleate ions could not and hence the selectivity is completely de