tnemhcrap fo teehs a dna nep lliuq rehtaef a:srehto ot saedi sieciatacinmoc yaw tnereffid a dnueh,yletanutroF. saW notlimaH neppah reven hgim raW yranoituloveR7h,nosreffeJ tuohtiw oot,gnht doog a AatAat AtaT. However, future work is required to understand the possible mechanisms linking chemical, morphological, hydration and charge properties of halloysite. Celestian tales old north guide Celestian tales old north walkthrough. Clear trends seem to relate particle morphology and structural Fe. Yet, hydration properties of the mineral probably play a major role in ion sorption. The occurrence of 2:1 phyllosilicate contaminants appears, so far, to provide the best explanation for the high charge and potassium selectivity of halloysite. No unique test seems to be ideal to distinguish these 1:1 clay minerals, especially in soils. This review summarizes the extensive but scattered literature on halloysite, from its natural occurrence, through its crystal structure, chemical and morphological diversity, to its reactivity toward organic compounds, ions and salts, involving the various methods of differentiating halloysite from kaolinite. Diversity also characterizes their chemical composition, cation exchange capacity and potassium selectivity. Delvaux, B.Ībstract Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states. This review summarizes the extensive but scattered literature on halloysite, from its natural occurrence, through its crystal structure. Halloysite clay minerals – a review Halloysite clay minerals – a review Abstract Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states.