Chlorite as a gangue mineral is associated with valuable minerals such as gold, copper and uranium. At low pH, chlorite leaching may generate viscous slurries, which deleteriously impact on metal extractions. The presence of fluorite (CaF2) as an accessory mineral phase may markedly affect leach behavior of chlorite. In this study, leaching and rheological behavior of chlorite were investigated over 5 h in the presence of varied concentrations of fluorite (chlorite to fluorite mass ratios of 20, 12, 10, 8 and 5 to 1) in sulphuric acid at 70ºC. Electron microprobe analysis indicated the chlorite chemical structure as [(Mg7.11Fe2+2.13Al2.65Fe3+3.89][Al2.60Si5.40]O20(OH)16. Incongruent leaching occurred, as evidenced by the kinetics sequence of the elemental species released in supernatants: Mg > Fe > Al > Si > Ca. Fluorite was found to enhance the leaching of chlorite due to the action of HF. Bulk analysis of leach residues by XRD showed gypsum formation as a secondary mineral phase. Rheological studies showed an increase of the yield stress during the leaching. Maximum shear yield stress was observed at chlorite to fluorite ratio of around 10:1. Surface chemical state analysis by XPS demonstrated that the chemical state of Si shifted from an initial alumino-silicate structure, gradually to structures of more silica/hydrated silica.