抄録
Recently, triple chain silicates which belong to biopyriboles were found by Veblen and Burnham. Biopyriboles are understood as polymerization series based on the concept of pyroxene slab unit. Present knowledge of stability of triple chain silicate is briefly reviewed. The genesis of triple chain silicate in metasomatism was examined in detail on many specimens from Akatani mine in Niigata Prefecture by high resolution electron microscopy. The concept of topotaxy index was introduced here and was used to interpret the tranformation mechanism. Taking account of the mode of occurrences of triple chain silicate in metasomatism, kinetics was considered. Triple chain silicate was assumed to be formed metastably, topotactically from clinopyroxene. The author's hypothetical composition-free energy diagram and reaction coordinate-free energy diagram were proposed. Intermediate depolymerizaton process in heating experiment of hydrous biopyriboles was also directly observed by high resolution electron microscopy.
