The book presents the main achievements of the world petrological physicochemical school of Russian academician D. S. Korzhinski. The theoretical foundations of the genetic classifications in metasomatic petrology are analyzed on the basis of equilibrium thermodynamic developed for natural processes. The author,s investigation of mineral equilibria in the system K2O-Al2O3-SiO2-H2O-SO3 is of particular importance for studying of the physicochemical conditions of mineral formation during the acid metasomatism of rocks. Physicochemical petrological investigations of the wallrock alterations in the Rodalquilar epithermal gold-alunite deposits (Southeast Spain) show the possibilities of obtaining important genetic data on an acid-sulfate type of gold deposit with a high degree of knowledge about it. The ideas advanced by Grunner and Kostov of the crystallochemical (energy and structure) aspect to the sequence of formation of silicate minerals are also confirmed in the complex and different metasomatic processes and formations (families).