EXPERIMENTAL TRANSFORMATION OF KAOLINITE TO HALLOYSITE

A well-characterized kaolinite has been hydrated in order to test the hypothesis that platey kaolinite will roll upon hydration. Kaolinite h ydrates are prepared by repeated intercalation of kaolinite with potas sium acetate and subsequent washing with water. On hydration, kaolinit e plates roll along the major crystallographic directions to form tube s identical to proper tubular halloysite. Most tubes are elongated alo ng the b crystallographic axis, while some are elongated along the a a xis. Overall, the tubes exhibit a range of crystallinity. Well-ordered examples show a 2-layer structure, while poorly ordered tubes show li ttle or no 3-dimensional order. Cross-sectional views of the formed tu bes show both smoothly curved layers and planar faces. These character istics of the experimentally formed tubes are shared by natural halloy sites. Therefore, it is proposed that planar kaolinite can transform t o tubular halloysite.