Abstract
Surface microtopography and internal textures of corresponding growth sectors of analcime from two localities in Japan were studied by means of polarizing and interference contrast microscopies. On the (211) face, a few large growth hillocks several mm in diameter and several hundred μm in thickness are noted. The hillocks are composed of flat surfaces with steps and also of rounded surfaces. The flat surfaces are almost parallel to the (211) face and the rounded surface is composed of high-index planes consisting of fine steps and kinks. Thin sections produced by cementing the growth surface on a glass slide show that most internal textures seen optically correlate well with growth patterns for both specimens.
These observations indicate that the characteristic internal textures seen on the optical micrographs are formed during the process of crystal growth, and that the symmetry of the sector grown on the vicinal faces {hll} is ordered tetragonal, while that of the sector produced on the rounded vicinal faces consisting of various kinks and steps is disordered isometric. The two-dimensional atomic arrangements exposed on the vicinal faces and their symmetries control the Al/Si ordering in the process of crystal growth.
