Full Description
It is our pleasure to present this large body of information and thoughts of many mineral scientists which has accumulated over decades. Illite is a mineral that has been discovered relatively recently, even though it has great importance in the geological cycles of weathering, sedimentation and burial. Illite is the major potassium mineral among silicates in the surface environment. Potassium represents the only alkaline metal, to be bound in silicate structures during the great chemical reshuffling called weathering. The weathering environment is one of strong chemical segregation, where Si and AI become the resistant, of silicate rocks. Iron forms an oxide and potassium forms residual elements the stable clay illite. Then Si and Al form smectites and kaolinite. Sodium, calcium and to a large extent magnesium are extracted from the solids as dissolved ionic species of the altering fluids. Ca and Mg are reintroduced into solid minerals via carbonate precipitation, and Na remains to make the sea saline. This mineral has been difficult to study because it is of fine grain size, as are all clays: 2 pm in diameter. Illite, along with other clays, had to wait to be discovered until a useful method of X-ray detection became available. With such a tool clays, whose definition was initially based upon the resolving power of an optical microscope (2 ]. lm), could be efficiently investigated. In fact the study of illite parallels the use and development of X -ray diffraction techniques.
Contents
The Mineralogy of Illite: Illite Definitions; Definition based on Chemical Composition; Thermodynamic Stability of Illite; The Growth of Illite Crystals; Working Definition of Illite.- The Geology of Illite: Illite in Soils and Weathered Rocks; Illite in Diagnetic Series; Illite in Fossil and Active Geothermal Fields and Hydrothermal Alteration Zones; The Illite Age Measurement.- Dynamics of the Smectite to Illite Transformation: Experimental Studies; Kinetics of Experimental Transformations; The Bulk Composition Effect.- Kinetics of the Smectite to Illite Conversion Process in Natural Environments; Success and Failure of the Multiparameter Models; Stability Controls; Application of Kinetics to K-Ar Dating.- Applications: Exploration and Exploitation of Natural Resources; Environmental Problems.
