The Mineralogy of Illite — What is Illite?

Abstract

The purpose of this chapter is to try to establish a guide line among the numerous uses of the term “illite”, considering first historical definitions, then recent advances in the fields of mineralogy and thermodynamics. The goal is to describe the variability of the crystal structure of illite in its different states of crystallization through X-ray diffraction, particle morphology and HERTM observations. If illite is “a phase”, we must understand how it can grow. From the examination of our present knowledge we hope to propose a “working” definition of illite before considering the way in which illite forms in natural environments.