Abstract: Studies on clays in Japan were begun about 1900. Modern clay mineralogical work began about 1940 and is being developed in the following scientific and industrial branches: geology, mineralogy, chemistry, ceramics, soil sciences, soil mechanics, etc. Recent important items are as follows: (a) Order-disorder problems of clay minerals. (b) Studies of clay minerals by electron micrographs and electron diffraction methods. (c) Mixed-layer minerals. (d) Studies on alteration products of volcanic glass. (e) Studies on sedimentary rocks and recent sediments. (f) Clay minerals associated with various kinds of ore deposits, and particularly wall-rock alterations. (g) Soil clay minerals, particularly of volcanic ash soils, paddy soils, etc. (h) Mineralogical and colloid-chemical studies of bentonites and acid clays. (i) Clay deposits for ceramic uses. (j) Studies of complexes between clay minerals and organic reagents. (k) X-ray studies on transformation of kaolin minerals.
The results emphasize certain general characters of Japanese clays such as a complex mode of association among clay minerals, or prevalent occurrence of minerals having a lower degree of crystallinity.