A crystallographic and kinetic study of the thermal decomposition of amphiboles

Abstract

This thesis embodies the results of a two part study of the thermal decomposition of amphiboles. The chief interest in this study has been to obtain a greater insight into the mechanism of the amphibole-pyroxene transformation, and to a lesser extent, the mechanism of formation of the other products. e.g. spinel and forms of silica. Part I is a single crystal study of the amphibole, cummingtonite. Identification of the product phases, and their structural relationships to the amphibole are discussed. This single crystal study was undertaken for two main reasons: 1. To study, in more detail than previously, the sequence of events in the formation of pyroxene. In particular to note the intensity changes, if any, of reflections during the transformation. 2. To continue the study of the effect of isomorphous substitution on the nature and orientation of the products.