PHYSICOCHEMICAL ASPECT OF METASOMATIC CRY STALLOGENY NON-PERMANENCY

Non-permanency of metasomatic process is the characteristic factor of crystal morphology formation. It is. A result of outer parameter chang e or heterogeneous system evolution under constant conditions. Synchro nous and interconnected processes of initial crystal dissolution and n ew crystal growth are the basic mechanism. That is the source of metas omatic non-permanency. Metasomatic reactions belong to 3 main types of physico-chemical systems that differ in mutual influence of component s on their solubility as well as in presence of isomorphic components. This is one of the bases of morphogenetic classification of replaceme nt products of single crystals suggested recently. Possible variants o l. metasomatic reaction course are analyzed for the most principal var ieties of systems under constant and changing temperature with the use of Schreinemacers concentration diagrams. Principal stages of such pr ocesses as well as correspondent morphological characteristics of new formations are discussed. The analysis; spreads ail over systems conta ining two and more non-isomorphic components or two isomorphic ones as well as having different configuration of isotherms and eutonic lines . We considered some features of congruent reactions as well as non-co ngruent ones that are inherent in all compositions of systems with iso morphic components and certain parts of systems with three or more eut onic lines. Calculation outlines for relative volumes of initial and f inal substances with pointed diagram employment are adduced. We discus sed kinetic differences of processes characterized by deficiency and e xcess of new formation volume.