SURFACE CHARACTERS OF TWIN DOMAINS AND EXSOLUTION LAMELLAE IN A FELDSPAR CRYSTAL - ATOMIC-FORCE MICROSCOPY STUDY

Atomic force microscopy (AFM) of a (001) cleavage surface of feldspar crystal reveals exsolution lamellae, wave-like (001) surfaces of the N a-rich lamellae, and surface steps with heights about 0.6 nm and 0.3 n m. The wave-like shape of (001) surfaces of albite twin domains result s from surface relaxation of periodic twin domains. Both twin boundary and twin composition planes are parallel to (010). AFM images with 3- dimensional information show surface height difference between Na-rich and K-rich lamellae in some areas, which indicates that the boundarie s are semi-coherent along the c axis. (C) 1997 Elsevier Science Ltd.