Shapes of Halloysite Particles in Japanese Clays

摘要: Hydrated halloysite clays altered from glassy tuff during weathering were examined in detail by x-ray, thermal, and electron micrographic methods. The micrographs show fibrous crystals of hydrated associated with many rounded grains, the former frequently jutting out latter. X-ray powder diffraction data thermal curves clearly presence halloysite, on closer examination dehydrated a small amount montmorillonite can be detected. allophane as an accessory mineral is suggested certain specimens. Furthermore degree crystallinity varies slightly specimen to specimen. variation kinds amounts clay minerals, shapes particles observed are generally related each other. relatively well-crystallized sort co-exists (dehydrated) consists elongated having sharp edges; grains composed entirely these crystals. On other hand, poorly crystallized tends extremely fine hairlike, twisted fibers; well-defined grains. A genetic process clay-mineral formation volcanic glass considered.