Secondary Albite from Granitoids of the Kudowa Zdrój Massif (Central Sudetes, SW Poland)

The value of angle s, which is between pericline composition plane (PCP) and the cleavage (001), was applied to the problem of origin of the albite from the Kudowa Zdrój granitoids. This angle reflects the primary anorthite content in plagioclase. On this ground, albites from the Kudowa Zdrój granitoids seem to be secondary after oligoclase probably due to the chemical reaction of ion exchange in the hydrothermal process. Analyses of the other types of twinnings in plagioclases (Carlsbad, Manebach, Ala-A, Ala-B) show the crystallization of these minerals from the magmatic melt (not by rheomorphism).