Muscovites genetic types of gold ore and crystal-bearing deposits of the Urals

Mica of muscovite-fengite series are ones of the most important rock-forming minerals of metamorphic and metasomatic rocks in various metallic and nonmetallic deposits. The temperature and pressure significantly affects their composition, determining the content of fengite and paragonite molecules. At present many important regularities of changes in composition of muscovite-phengites are revealed in different parageneses of metamorphic rocks under the influence of temperature and pressure. Increasing of AlIV at higher temperatures is now the general rule for the majority of silicates of metamorphic rocks. The effect of pressure has the inverse effect - fengites is increased and the alumina content is decreased. High-pressure parageneses are located in the field of phengites and ferrifengites. It is shown the possibility to determine the temperature and pressure of metasomatic rocks formation using data on chemical composition of muscovite and X-ray data.