Plagioclase fabrics in some metablastic rocks

Abstract

A peculiar orientation of plagioclase porphyroblasts hag been ascertained in some blastic rocks. There are several types of intergranular coordination between neighbouring plagioclase blasts. They are laid facing the equivalent crystallographical planes each other or in twin-like relation. Detailed measurements of these plagioclase fabrics told us that the symmetry elements revealed in one crystal also effectively govern over the two or more neighbouring plagioclase grains without any distinctions whether they are in direct contact or separately formed.