Role and significance of interior boundaries at magmatic rocks

The paper deals with intergrowth boundaries of mineral grains in igneous rock in terms of their geometry, crystallography and energy accumulated in the course of ontogenesis of individuals and their aggregations. So, all the geometric features of the boundaries, such as the area, length, angular relationships, can be obtained in flat cross-sections of mineral aggregates or in petrographic thin sections, which are used to diagnose rock-forming and accessory minerals as well as rocks. Crystallographic identification of the boundaries of mineral individuals can also be measured and calculated for most of the boundaries in thin sections; sometimes the characteristic of flat cross-sections of mineral grains can be used according to the degree of cross-section contours’ approximation to idiomorphic or xenomorphic forms. The energy characteristic of the mineral aggregate internal boundaries can be estimated indirectly as a result of calculating the projection of a unit cell of the mineral grain’s crystal lattice on the plane of the individual's boundary. Each of these methods of consideration and characteristics of individual’s boundaries and intergrowth’s boundaries in the aggregate is a source of information for the restoration of comparative conditions for the mineral aggregate formation, ontogenesis.