抄録
In soils, we can find clay minerals, whose formation is more or less specific to soil environment. Their structures and properties as well as formation processes provide unique and interesting subjects in clay mineralogy. Examples are taken in this review based on the author's own interest. Studies on allophane, imogolite' and halloysite have shown that weathering of finely comminuted volcanic ash well reflects the effects of climate, vegetation, and time, and produces minerals of unique structures. “Vermi culite or smectite-chlorite intergrades” have been reported in many temperate soils, but there are indications that their “interlayer” materials are other than polymer hydroxy-aluminum ions. A possibility that at least some of these “intergrades” represent an intermediate phase in the transformation from a 2:1 type layer silicate to a 1:1 or another 2:1 type layer silicate during weathering is suggested.
