The reactivities of olivine and serpentine towards mixture of chlorine in air, nitrogen and carbon monoxide were studied in non-isothermal conditions up to 1000°C. The samples were also chlorinated in a horizontal reactor over 2 h between 500° and 1000°C, under oxidizing and reducing atmospheres. The chlorination products were examined by XRD and SEM. The iron-bearing compounds contained in the natural olivine and serpentine samples can be eliminated through chlorination or oxychlorination of these solids at temperatures lower than 900°C. Carbochlorination of olivine and serpentine is incomplete even at 1000°C for a reaction time of 2 h. Pure magnesium chloride can be recovered by cooling the gas phase at ca. 500°C.