Abstract
Morphology of well-ordered kaolinite (Keokuk, Iowa) crystals has been analyzed by using the high-resolution SEM and EBSD technique. Elongated hexagonal crystals always show the a-axis parallel to the elongated direction. The side-facets of these crystals are in parallel to the c-axis that is inclined by about 15° from the normal of the basal plane. In other word, the miller indices of the side-facets are exactly ±(110), ±(1-10) and ±(010). A facet indexed as ±(1-30) is occasionally developed. These morphological features must be reflected in the ordered stacking sequences (the position of the octahedral vacancy site and the direction of the interlayer shift) in the kaolinite crystals. Inversely, crystallinity of individual kaolinite grains may be evaluated from their morphology in a SEM.
