Iron cations in the octahedral sheet are a disadvantage to the industrial application of palygorskite clays. In this study, a palygorskite sample from eastern China (Mayaoshan deposit, Jiangsu Province) is shown to have an Fe content that is much greater than usual. The structural formula of the Fe-rich palygorskite sample was established as (Si7.48Al0.52) (Al1.24Fe0.94Mg1.77Ti0.03⁏1.02)O20(OH)2(OH2)4. The palygorskite is seen to be dioctahedral according to the structural formula, consistent with Fourier transform infrared data. Occurrences of AlFe3+ɏOH and Fe3+Fe3+ɏOH vibrations in the OH-stretching and -bending regions show that Fe atoms occupy inner sites of octahedral sheets. A Mössbauer spectrum confirmed that Fe ions occupy inner octahedral sites as trivalent Fe cations (Fe3+).
