Microflotation experiments conducted with pyrite showed that the mineral acquires considerable floatability upon superficial oxidation. The flotation occurs at potentials anodic to the stable potential of the mineral identified by chronoamperometric studies conducted on freshly-fractured pyrite electrodes. It is believed that sulfur-rich species, such as iron polysulfides, formed during the initial stages of oxidation are responsible for the flotation. The collectorless flotation of pyrite is suppressed in strongly oxidizing and moderately reducing environments.