In the manufacture of ordinary Portland cement, the clinker is inter-ground with mineral gypsum which provides sulphate ions to regulate hydration of calcium aluminate (C3A) phase resulting in retardation of cement setting.The available sulphate ions assist in formation of temporary coating of gelatinous ettringite on the hydrating particles of C3A causing delay in its hydration reaction.In the by-product jarosite, the presence of mineral phases such as natrojarosite, gypsum and anhydrite contribute in sulphate ions resulting in its utilization potential in regulating cement setting similar to mineral gypsum.The physical characteristics of OPC and PPC samples prepared using 5% gypsum which is made up of mixtures of mineral gypsum and jarosite in different proportions showed comparable setting behaviour.Long term compressive strength developments of OPC and PPC cement mortars prepared by partially replacing mineral gypsum by jarosite and cured under different aggressive environments containing sulphate, chloride and alkaline salts up to 24 months showed strength developments comparable to the cement samples containing only mineral gypsum and cured under lean water.The above cement samples also showed negligible amount of leachates indicating fixation of heavy elements in hardened cement matrix