Clay minerals of volcanic ash in japan

Soils formed from volcanic ash distributed by several volcanos in the northeastern part of Japan have been studied by means of X-ray diffraction, infrared spectroscopy, differential thermal analysis and chemical analysis. The content of amorphous materials of the clay less than one micron is about seventy five per cent in the early stage os weathering, and is about forty per cent in the advanced. The essential minerals of the soils in every stage of weathering are 14A clay minerals. The kaolin minerals are found in small amounts. The weathering sequence of the volcanic ash soils in this district based on the mineralogy appears to be as follows: Volcanic ash soil - allophane - montmorillonite - vermiculite-Al chlorite intergrade The small amounts of halloysite, Al-chlorite and illite are found in every stage.