Abstract: Seven natural zeolite minerals from different region of China have been studied byXRD, IR, DTA and ESR methods for the structure, purity and acidic property characteri-zation.It is found that six of the zeolite samples are twin minerals of mordenite and cli-noptilolite and have the following order according to their mordenite content: C-2≈NZ-3>NZ-7>NZ-2>NZ-1 Zeolite C-1 is a pures clinoptilolite.Mineral NZ-6 is a kaolinite of high purity.ESRmeasurements showed that all zeolite samples give Fe³⁺ in large content and different con-tent of Mn²⁺, while NZ-6 shows O₂^- signals in ESR spectra as a result of absorbed oxy-gen from air.

Key words: natural zeolite, mordenite, clinoptilolite, kaolinite, physico-chemical property