Introduction to the theory of forced equilibria: General principles, basic concepts, and definitions

Abstract

Until now, only a small amount of work has been done to verify the constraints of using fundamental regularities of the exact sciences in geochemistry and mineralogy. As for the chemical thermodynamics, the most important problem is the inadequate presentation of the thermodynamic state of real mineral systems. Our contention is that this state cannot be rigorously referred to any conventional type, if examined by the traditional chemical thermodynamics, and must be analyzed in terms of forced-equilibrium theory. The forced equilibrium is defined as a specific thermodynamic state resulting from the action of forcing factors, that is, the conditions or constraints which restrict possible variations of principal or internal thermodynamic system parameters. The advantage of this approach is that it proceeds from the operative forcing factor to the actual type of equilibrium of the real system, whereas the traditional analysis usually postulates the type of equilibrium state without proof of adequacy. The equilibrium conditions for thermoelastic solids with a coherent interphase boundary are a good example of forced equilibrium. The numerical modelling of forced equilibria in some real mineral systems and the comparison of the results with experimental and natural data show that the actual thermodynamic states of mineral systems more often represent stable or metastable forced equilibria than kinetically depressed or metastable states in their traditional understanding.