A critical review of the accumulated data on the physical chemistry of silicon and its binary systems is provided. The properties and descriptions of the crystalline structures of silicon and all currently known ero binary compounds are described in detail and the main ways of their practical use are indicated. Particular attention is paid to the silicon-oxygen system, in particular silica, which is of exceptional importance for the geological and mineralogical sciences and silicate technology. New silica state diagrams are provided. A significant place is also allocated to silicon carbide (carborundum) and transition metal silicides. All sections are provided with a historical overview. The main literature on the presented issue is given. The book is designed for chemists, silicate technologists, metallurgists, geochemists, petrographs, mineralogists.