The physics of minerals in a broad sense implies the fundamental aspects of understanding mineral matter: the electronic structure of atoms related to their behavior in geochemical processes; the atomic and electronic structures of minerals; the properties of minerals, with their genetic, geophysical, and technical significance, and their pressure and temperature dependence; the mechanisms of phenomena and reactions in mineral formation and transformation processes; the physical me­ thods applied in mineralogical, geochemical and petrological studies, and to a great extent in geological surveys and prospecting. In a narrower sense, it is a branch lying in the border area between mineralogy and solid-state physics, dealing with those aspects of mine­ ralogy which require, for their understanding and investigation, special knowledge in contemporary physics and chemistry of solids. The physics of minerals accounts for the third crucial change within this century in the conceptual foundations of mineralogy: after physi­ cochemical mineralogy, from experimental studies of phase relations to parage netic analyses, and crystal chemistry of minerals, there followed solid-state physics, which has evolved to its present state over the past 25 years. The task of mineralogy has expanded greatly. In addition to the identification and description of minerals, it is becoming necessary to establish the relationships between structure, composition and properties of minerals and their genesis, their distribution within geological regions, magmatic, metamorphic and sedimentary formations and types of ore deposits. The development of new methods of investigation requires an understanding of the physical meaning of the parameters under evaluation.