The present textbook has been prepared in compliance with the course in mineralogy set by the university curriculum. The first part contains a traditional crystallochemical characterization of minerals. Information on the types of crystalline structure and structural motifs of minerals has been supplemented by a discussion of polymorphic modifications and polytypes. A special section dealing with structural imperfections (defects) has also been introduced. Phenomena pertaining to isomorphism, resolution of solid solutions have received due prominence together with the role of water in the composition of minerals. The graphical representation of the chemical composition of minerals and the calculation of crystallochemical formulae have been illustrated. The description of physical properties is discussed in terms of their nature, the methods of their analysis and the importance for diagnostic purposes, in prospecting, the enrichment of ores, technology, etc. <...>

The clay minerals are small hydrous layer silicates and are part of the phyllosilicate family. As discussed in Chapter 11, many of the hydrous layer silicates in clays, muds, soils, shales, slates, etc. are coarser than clay (< 2 or < 4 pm). Primarily for this reason I have suggested (Weaver, 1980) using the term physil, which has no size connotation, to refer to the low-temperature ( 5 400°C) hydrous layer silicates.

The name bentonite was suggested in 1898 by Knight for a peculiar claylike material with soapy properties from its occurrence in the Fort Benton unit of Cretaceous age formations in Wyoming (U.S.A.). Hewitt (1917) and Wherry (1917) first established that this particular clay is an alteration product of volcanic ash, although an earlier observation by Condra (1908) suggested this origin for a similar clay from northern Nebraska. Ross and Shannon (1926) presented the following definition which has been widely quoted:

Have you tried to walk across a farmer’s field in Montmorillon in France on a rainy October day? Marcel and Bertrand, his father, tried to do so in the fall of 1881 with fatal consequences. We will return to this terrible true story in the first chapter of this book for explaining how the soil at this place made it happen, continuing throughout the rest of the book by explaining how the dreadful soil, in fact, also has extremely beneficial properties in other contexts, like isolation of very hazardous waste.

The writer wishes to acknowledge the help of Dr. R. E. Grim of the Geology Department of the University of Illinois for supervising this work and for reading and criticizing this paper. Grateful acknowledgement is also made to Dr. W. F. Bradley of the Illinois Geological Survey and to Dr. G. W. Clark of the Chemistry Department of the University of Illinois for helpful suggestions in the theoretical and experimental X-ray work; to Dr. D. T. Englis of the Chemistry Department of the University of Illinois for allowing the use of the microphotometer; to Dr. M. M. Knechtel of the U. S. Geological Survey for making possible the field study of the Wyoming bentonite deposits; to the Baroid Sales Division of the National Lead Company for granting the fellowship under which this work was done and for supplying many of the samples which were used for study and to the geologists and chemists of that organization for allowing the use of their physical property determinations. <...>

The word “clays” was assigned early to fine grained material in geological formations (Agricola 1546) or soils (de Serres 1600). Clays have been identified as mineral species in the begining of the 19th century in the production of ceramic materials (Brongniart 1844). Then Ebelmen (1847) carefully analyzed the decomposition of rocks under chemical attack and the way that porcelain can be commonly made. Since this pionner works, the definition of clays has varied.

1. Описание октаэдрического кристалла пирита с Урала

2. О кристаллах пироксена из местности между Сурамским перевалом и Зварским ущельем

3. К вопросу о "ромбическом сечении" у плагиоклазов

4. Своеобразный кристалл турмалина

5. О двойнике турмалина

6. Амазонский камень из копи Мельникова

7. О двух горных породах с содержанием корунда и алювита

8. О кристаллах увльфенита из Кас-Кай-Гыра, Каркаралинского у.Секипалатинской области

This is the tenth book of a series which began in 1974 under the title Short Course Notes. In 1980 the Mineralogical Society of America changed the name and institutionalized this serial under the title Reviews in Mineralogy. The books published thus far are listed on the opposite page (p. ii); they are available at moderate cost from the Society. Volume 9B, "Amphiboles: Petrology and Experimental Phase Relations," was begun in 1981 in preparation for the Short Course on Amphiboles and Other Hydrous Pyriboles presented at Erlanger, Kentucky, October 29 - November 1, 1981, prior to the annual meetings of the Geological Society of America and associated societies. Unfortunately, only the first chapter was in manuscript form at the time of the short course, and publication was delayed by one year. Its printing coincides with that of Volume 10, "Characterization of Metamorphism through Mineral Equilibria," edited by John M. Ferry. <...>