Abstract:The retrograde metamorphism of eclogites in Dabieshan area can be divided into fluid-poor, fluid-bearing and fluid_rich stages. Recrystallization, polymorphous conversion and exsolution of rock_forming minerals of the eclogites seem to have been the main processes of the fluid-poor stage. The fluid_bearing stage proceeded at high temperatures and pressures, and is characterized by the participation of minor fluids. White mica formed at this stage is dominated by phengite. Due to the participation of large quantities of fluids, the fluid_rich stage is characterized by the formation of various low-pressure and hydrous minerals including a variety of white micas. White mica formed at earlier fluid_rich stage is dominantly phengite, with atom number of Si varying between 6.5 and 7.2 pfu. White mica of the late fluid_rich stage is markedly variable in composition, consisting of paragonite, muscovite and margarite. Biotite is the last kind of mica formed in the process of diaphthoresis. Also studied in this paper is a zoned structure of retrograde mica, which consists of an inner zone of paragonite, an intermediate zone of muscovite-margarite intergrowths and an outer zone of biotite.