SURFACE MICROTOPOGRAPHY OF INTERSTRATIFIED MICA AND SMECTITE FROM THEGOTO PYROPHYLLITE DEPOSIT, JAPAN

By means of a gold decoration transmission electron microscopy (TEM) t echnique, interlaced spiral steps with a 10 A step height were observe d on (001) surfaces of lath-shaped or elongated hexagonal rectorite cr ystals, i.e. interstratified mica-smectite minerals, from the Goto pyr ophyllite deposit in Nagasaki Prefectura, Japan. This is the first dir ect evidence to demonstrate that the growth of interstratified mica-sm ectite takes place by the spiral growth mechanism. The interlacing pat tern is interpreted as appearing by co-operation of two hexagonal spir al layers of mica and smectite-like layers which have originated from a single dislocation and are stacked by rotation of 60-degrees.