Abstract: The objectives of this study are to record the occurrences of the alunite in the Kaolinite beds of the Hiswa Clay Deposits, South Jordan and to explain its possible mode of origin. The results of the field, chemical and mineralogical studies indicated that the alunite is present as minor and trace constituents (0.79-2.65%) in kaolinite bed of the Hiswa clay deposits, South Jordan. The alunite occurs as small white spots along bedding planes within the lower part of the Shale Member, which belongs to the lowest part of Hiswa Sandstone Formation. The Hiswa Sandstone Formation contains well preserved graptolite of middle Ordovician. The sulfur trioxide (SO3) content (0.42-1.44%) is related to the presence of gypsum and alunite. Iron sulfides (source of sulfur) could be originally produced by mineral replacement of chitinous tests of graptolites in oxygen deficient marine environment.