An Attempted Classification of Pegmatite Structures

Abstract

An attempt is made to classify structural features of simple pegmatites and pegmatite-like rocks based on observations from the archipelago of SW Finland. The following structures are treated: the shape of the pegmatites, the shape of the contacts, the zoning, the fabric, and the relation to tectonics. On the basis of the structures it is further concluded that the pegmatites arc polygenetic. There occur all transitions from crystallization from magmas or pneumatolytic rest magmas through metasomatism to more or less pure recrystallization with or without loss of water.