The study of complex mineral and inorganic structures by means of computer graphics

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This project may be divided into two major parts. One is to develope a graphic program for calculating crystal structures on personal computers, such as those of the NEC 98001 series. The program must be suited for studying mineral and inorganic crystal structures. The other is to apply the program to study very complex mineral structures, specifically the plagionite group of minerals. The results obtained in the assigned period are summarized below.1. A MS-DOS version was made of the program CRYSTAL which had been written by M. Hirano with n88BASIC. The new improved version, denoted CRYSTAL 18, has various functions which are not available in the original program. Some of the major functions added are: (1) any thin slice of a given structure can be made and displayed and (2) four diagrams having a series of different orientations can be displayed simultaneously.2. The substructure-superstructure rational relationship has been established for plagionite, Pb_5Sb_8S_<17>; the transformation matrix has been derived to relate their sets of crystallographic axes. Further study extended to the fuloppite structure has fully elucidated the mechanism of cell-twinning underlying the whole plagionite group.The results achieved by the present stusy would provide, for example, considerable contribution to the promotion of the systematics of sulfosalts and in general to that of the structural study of minerals and inorganic materials.