Plagioklazy

Abstract

PLAGIOCLASES Summary The paper deals with the inclination of plagioclases to form twins. The most important twinning laws are discussed, and the frequency of their occurrence and distribution in rocks of various origin are given. Similarly, there are discussed also temperature properties of plagioclases, and the history of discovering and studying these phenomena. Moreover, the author presents zoning in plagioclases, origin of both oscillatory and normal zonings, and gives the methods of investigating the phenomena considered. All the properties are discussed from the viewpoint their usefulness in studying petrogenetics.