Partitioning of cations between coexisting single-and multi-site phases: A reply with incidental corrections

Abstract

Although the use of chemical potentials in treating species on sites within a single phase is formally correct, the use of potential differences or of other kinds of potentials may prove operationally more useful in the long run. The one site-two site model of Grover and Orville (1969) provides a reasonable explanation for existing Mg-Fe 2+ distribution data for coexisting ortho-and Ca-clinopyroxenes and, in the face of abundant evidence for intracrystalline partitioning in orthopyroxene, is preferred over a one-site model. The relations derived by Grover and Orville are correct, although several can be simplified.