Some Results of the Study of Clay Minerals in the U.s.s.r.*

Clay mineral studies in the U.S.S.R., mainly since 1960, are summarized. Electron diffraction techniques especially have been developed and used extensively. Methods have been developed for simultaneous recording of DTA curves and other properties. Polytypism of phyllosilicates has been studied intensively by Zvyagin and others. Mucfi new information on the structure and morphology of halloysites has been obtained by electron-optical methods. Other clay minerals extensively studied include allophanes, kaolinites, chlorites ("donbassite" is preferred to "sudoite" for dioctahedral varieties), alushtite (or tosudite), monothermite, and various zinc-bearing clays. Much attention has been given to physico-chemical and colloid-chemical properties. The natural occurrence and alteration of clays and clay minerals are described in weathering and oxidation zones, in soils, and in Recent and Ancient sediments. Primary clay minerals of hydrothermal origin are described. INTRODUCTION THE study of clay minerals in the U.S.S.R., as in many other countries, was begun in connection with the practical utilization of kaolinitic and montmorillonitic clays. At the end of the nineteen thirties and forties the interest in clay material had sharply increased; a great number of publications appeared on the mineral composition of clays, their origin and practical use. Concurrently, research began on the clay minerals in the weathering zone, the oxidation zone, soils and sedimentary rocks; much attention was paid to the role of clay minerals in engineering construction. Somewhat later there was a broad development of investigations devoted to the physico-chemical and colloid-chemical properties of clay minerals and to their crystalchemistry. The author's aim is to present some results of the study of clay material by Soviet specialists, mainly during the last decade.