Preface

A solid-solution series is the continuous sequence of substances with compositions intermediate between two distinct mineral phases, called end members. In a solidsolution series, the components may be thought to substitute for one another on a molecular level in the crystal structure; the intermediate members have properties that vary continuously with composition from those of one end member to those of another. Solid-solution series are said to be complete if examples of complete variation exist in nature or have been synthesized in the laboratory. . . . . . only the appearance of the computer provided a qualitative jump and made it possible to perform effective study of really complex systems in various areas of knowledge. Actually, the concern is with coarse qualitative criteria, differentiating simple systems from complex; if the structure and behaviour of a system can be studied by a single man in a reasonable time, the system is called simple. If the efforts of many persons and the use of special technical equipment (computers) are required to draw the whole picture, the system is called complex.