The article covers factors that determine fundamental difficulties of chemical phase analysis of a mixture of solid phases of inorganic compounds. Stoichiographic principles and methods, novel for analytical chemistry and leading to the efficient solution of the problems of phase analysis, are discussed. Conditions of the selective separation of mixtures of multiphase multielement solid compounds and principles of the new method, fan-like separation, ensuring the extraction of individual phases from unseparated mixtures, are considered. An idea of a complex method of solving analytical problems by stoichiography methods in proposed. The problem of the multiplicity of objects of analysis is discussed and general principles of the efficient solution of problems of the detection and identification of components of complex mixtures of unknown chemical composition are considered.