Relationships between the inorganic colloid and the parent material of some volcanic ash soils in Miyagi and Iwate Prefectures, Japan

Relationships of the inorganic colloid to the parent material were studied on 13 volcanic ash soli samples taken from Miyagi and Iwate prefectures. Allophane and imogolite were predominant in the soils derived from basaltic or andesitic ashes, while 2 : 1 and 2 : 2 type layer silicates, alumina-rich gel-like materials, and allophane like constituents were abundant in the soils of quartz andesitic ash origin. A randomly interstratified mineral of halloysite and 2 : 1 type layer silicates was found in the fine clay fraction of fairly well-weathered quartz andesitic ash soils. The clay mineralogical compositions of volcanic ash soils were distinguished from each other in terms of the petrological nature of their parent ashes.