Abstract
The crystal structure of a kaolin mineral Al2Si2O5(OH)4 from the northeast of Yaita city, Tochigi Prefecture has been investigated with the procedure of the X-ray powder pattern-fitting. Assuming a two-layer monoclinic cell, three models with different modes of kaolin-layer stacking were derived. The least-squares fitting of the calculated pattern to the observed one selected out a correct model, giving the final R-value (profile) of 0.067 for 1301 observed intensity data measured with CuKα radiation in the range 15°≤2θ≤80°. The present specimen, which was reported previously to bs a six-layer new polytype of kaolin minerals, has been proved to be an aggregate of nacrite crystals containing a small amount of α-quartz and an amorphous material.
