The formation of omphacite in blue jadeitites by the Cottrell atmosphere

Abstract

The dusty blue jadeitites from the Kotaki River, Niigata Prefecture, Japan have been analyzed by transmission electron microscopy (TEM) and electron probe microanalyzer (EPMA). The dendritic texture which is made up of omphacite and concentrates minor element such as diopside and acmite components, is found in blue area. The dendritic texture has subgrain boundaries and cell structures where dislocations are tangled up. The concentration of trace elements and the existence of many dislocations in dendritic texture indicate that omphacites are formed by the Cottrell atmosphere.