As this excellent book demonstrates, the study of comets has now reached the fas cinating stage where we understand comets in general simple tenns while, at the same time, we are uncertain about practically all the details of cometary nature, structure, processes, and origin. In every aspect, even including dynamics, a choice among several or many competing theories is made impossible simply by the lack of detailed knowledge. The space missions, snapshot studies of two comets, partic ularly the one that immortalizes the name of Sir Edmund Halley, have produced a huge mass of valuable new infonnation and a number of surprises. Nonetheless, we face the tantalizing realization that we have obtained only a fleeting glance at two of perhaps a hundred billion (lOll) or more comets with possibly differing natures, origins, and physical histories. To my personal satisfaction, comets seem to have discrete nuclei made up of dirty snowballs, as I concluded four decades ago, but perhaps they are more like frozen rubbish piles.

Reviewers of the German edition of this book found that the text deals with facts and descriptions of limestones rather than with glo- bal speculations on facies models or large-scale sedimentation pat- terns. The book is neither a picture-book nor a recipe-book for facies interpretation of carbonates, but an attempt to summarize the present "state of the art" of a rather small but increasingly more im- portant part of geology. The book is written for advanced undergraduate and post-grad- uate students as well as for research workers and exploration geol- ogists who need rapid and intensive training in modern methods of microfacies analysis. The book should facilitate decisions about which methods to use in one's own investigations, and where to look for comparative studies. Microfacies interpretation of carbonate rocks can not rely solely on the investigation of sedimentological and paleontological thin- section data, but must also consider geological and palecological cri- teria. It is beyond the scope of this book to describe all of these as- pects. However, broader applications are indicated in the chapters dealing with the relationships between geochemical as well as physi- cal data and the depositional and diagenetic fabric oflimestones.

The original Russian edition of the monograph Paleozoic salt forma- tions ofthe world was published by Nedra, Moscow, in 1974. The description of salt basins was given as of 1970-1971 and based on the literature available at that time. Additional evidence was pre- sented in History of Paleozoic salt accumulation (Nauka, Novosibirsk 1978), with abrief account of new basins of Paleozoic salt accumula- tion. These two books complement each other and have one common list of references, the former providing the material which in the latter is the basis for the major trends in the history of evaporite sedimenta- tion in the Paleozoic. History ofPaleozoic salt accumulation was the first ofthe two books to be published in English (Springer, Berlin, Heidelberg, New York 1981). The present book is the first synthesis dealing with specific Paleozoic salt formations and some salt basins. However, since the first edition was published 10 years ago, new data since then allow more accurate and detailed description of composition, structure, and dis- tribution patterns of salt deposits within Paleozoic evaporite basins. New basins have also been found in some regions of the Earth. The author has attempted to give more complete characterization of Paleo- zoic salt basins using the data available as of 1981.

Documenting a joint Chinese-European study of mesothermal lode gold deposits from early Precambrian rocks of E. Hebei Province (NE China), introductory chapters on gold deposits, and the basement geology of the Sino-Korean Platform are followed by detailed descriptions of the individual gold desposits. These include descriptions of the lithology and structure of the host rocks, ore geochemistry and petrography, and wall-rock alteration. Radiometric ages, fluid inclusion data, and C-O-H-S-Pb isotopic compositions of ore and gangue minerals constrain the timing, physical conditions and the possible origin of mineralization. An important conclusion is that, in contrast to the Archean greenstone-hosted gold desposits in Canada, Australia and Africa, the Chinese examples occur in high-grade polymetamorphic rocks, and the main impetus for mineralization was tectonism and granitic magmatism of the late Mesozoic Yanshanian orogeny. This book will be of considerable value as a source of specific information and extensive references about gold deposits and Archean geology in NE China, and should be equally interesting to geologists working on Archean gold geology and those concerned with Mesozoic Circum-Pacific metallogeny.

We wrote Sedimentology of Shale primarily because we lacked a handy, reasonably comprehensive source of information and ideas about shales for students in our sedimentology program. It was also our feeling that the time for shales to receive more study had finally arrived. Sedimentology of Shale also seems very timely because today more sedimentologists are interested in shales. Certainly in the last five years the pace of shale research has no ticeably quickened because the role of shales as important sources of oil, gas, heavy metals and as a long understudied part of the earth's geologic his tory has been recognized. Noteworthy developments include the elucida tion of the importance of trace fossils in shales, the discovery of thick sequences of overpressured shales in regions such as the Gulf Coast (which have important implications for hydrocarbon migration and faulting), the ex tension of the principles of metamorphic facies to the realm of low tempera ture diagenesis by study of the organic matter in shales, and shales as ul timate sources for mineral deposits. Accordingly, we decided it was timely to write a book on shales. In one respect, however, ours is an unusual book. Most books in geology are produced after one or two decades of progress have been made in a field and attempt to summarize and evaluate that progress."

33 14. 3. 5 REE between Plagioclase and Aqueous Fluid 0 Cullers et al. (1973) measured the distribution of REE at 850 C and 750 bars pressure between a natural plagioclase, An, and gaseous water. The rare earths 65 favored the plagioclase by a factor which varies from about 25 for Ce to 10 for Lu. Data were also obtained for forsterite, diopside, enstatite and two rhyolite glasses, on the one hand, and water on the other hand, thereby permitting estimation of the partition coefficients between all pairs of phases. 14. 4 Chemical Substitution in Natural Feldspars 14. 4. 1 Introduction It is quite impracticable to give all the data on chemical substitution in natural feldspars: indeed many of the details are significant only to some particular pegmatite or rock body. As far as possible, emphasis is placed on features of general interest to crystal chemists and to petrologists. Ironically the well established features can be described more easily than the uncertain ones, and unfortunately it is necessary to use valuable space on data of dubious value. The bibliography is fairly complete, but it was impracticable to locate all data, especially those in obscure journals. Each reference is followed by a list of the elements referred to in the paper, thereby permitting a reader to compile a fairly compre hensive set of references on any chosen element. Not all papers are mentioned in the text. The book on Geochemistry and Mineralogy of Rare Elements, etc."

During the last five years transmission electron microscopy (TEM) has added numerous important new data to mineralogy and has considerably changed its outlook. This is partly due to the fact that metallurgists and crystal physicists having solved most of the structural and crystallographic problems in metals have begun to show a widening interest in the much more complicated structures of minerals, and partly to recent progress in experimental techniques, mainly the availability of ion-thinning devices. While electron microscopists have become increasingly interested in minerals (judging from special symposia at recent meetings such as Fifth European Congress on Electron microscopy, Man chester 1972; Eight International Congress on Electron Microscopy, Canberra 1974) mineralogists have realized advantages of the new technique and applied it with increasing frequency. In an effort to coordinate the growing quantity of research, electron microscopy sessions have been included in meetings of mineralogists (e. g. Geological Society of America, Minneapolis, 1972, American Crystallographic Association, Berkeley, 1974). The tremendous response for the TEM symposium which H. -R. Wenk and G. Thomas organized at the Berkeley Conference of the American Crystallographic Association formed the basis for this book. It appeared useful at this stage to summarize the achievements of electron microscopy, scattered in many different journals in several different fields and present them to mineralogists. A group of participants as the Berkeley symposium formed an Editorial Committee and outlined the content of this book."

Biominerals are generated by the subtle interaction of biological organization and mineral growth. They belong both to the living and the inanimate world and as such their genesis is among the most intri guing and fundamental subjects in science. However, the conceptual and technical resources that are available in physical chemistry and in the biological sciences is often inadequate for the elucidation of the pro blems involved, and hence this field is particularly difficult to ex plore. This may be an important reason why fundamental research on bio mineralization mechanisms has traditionally been carried out by a com paratively small group of scientists. There are signs, however, that the situation is ripe for a change. Various meetings on biomineralization have been organized in the last few years, particularly in the medical sector. It is generally felt that further developments in the therapy of bone and tooth diseases will be largely dependent on an improved understanding of the fundamen tal underlying mechanisms of biomineralization."

Students of a phenomenon as common but complex as andesite genesis often are overwhelmed by, or overlook, the volume and diversity of relevant information. Thus there is need for periodic overview even in the absence of a dramatic breakthrough which "solves the andesite problem" and even though new ideas and data keep the issues in a state of flux. Thus I have summarized the subject through mid.1980 from my perspective to help clarify the long-standing problem and to identify profitable areas for future research. Overviews are more easily justified than achieved and there are fundamental differences of opinion concerning how to go about them. It is professionally dangerous and therefore uncom mon for single authors, especially those under 35 such as I, to summarize a broad, active field of science in book-length thor oughness. Review articles in journals, multi-authored books, or symposia proceedings appear instead. The single-authored approach is intimidating in scale and can result in loss of thoroughness or authority on individual topics. The alternatives lack scope or integration or both."

In modern sediment research on contaminants five aspects are discussed which, in an overlapping succession, also reflect develop ment of knowledge on particle-associated pollutants during the past twenty-five years: (1) identification of sources and their distribution; (2) evaluation of solid/solution relations; (3) study of transfer mecha nisms to biological systems; (4) assessment of environment impact; and (5) selection and further development of remedial measures, in par ticular, of dredged materials. Scientific research and practical develop ment are still expanding in all these individual aspects. Similar to other waste materials, management of contaminated sed iments requires a holistic approach. This means that assessment of biogeochemical reactions, interfacial processes and transfer mecha nisms as well as the prognosis of long-term borderline conditions, in particular of capacity-controlling properties, should be an integrated part of the wider management scheme, i.e., the analytical and experi mental parameters should always be related to potential remediation options for a specific sediment problem. The underlying coordinated project, which was funded by the German Federal Ministry for Science and Technology (now the Federal Ministry for Education, Science, Research and Technology) provided excellent opportunities for multidisciplinary effort, bringing together biologists, chemists, engineers, geologists and other researchers. During its active phase, the group attracted much interest nationally and internationally. The group members highly appreciate the manifold contacts and invitations during the past five years."

In May 1976 Lucian B. Platt organized a highly successful Penrose Confer ence on The Formation of Rock Cleavage at Bryn Mawr College in Penn sylvania, U. S. A. The meeting drew together about 70 specialists from both sides of the Atlantic and from Australasia, who contributed discussions on various aspects of rock cleavage and its formation. Even early in the meet ing it became clear to the participants that they lacked a common terminol ogy, that often the same technical word implied different things to different people and that observables and descriptors were loosely defined. In an at tempt to improve communication the present editors contacted about 190 workers after the conference with a view to compiling a set of photographs with captions to illustrate exactly what workers were talking about. As a re sult the compilation was published as a limited edition by an inexpensive offset process at the University of Tasmania. The success of that provisional edition of the Atlas of Rock Cleavage and the responses of the readers prompted us to make a more extensive collection of material, contact a wider range of workers and, with the support of Dr. Konrad Springer, to publish the present higher-quality reproduction of the contributors' plates."

It is the policy of the federal Canadian Forestry Service to sponsor research initiatives from the private sector that are judged to be pertinent to its mandate and offer particular promise towards the optimal management of Canadian forest resources. This book is based on such an initiative. It represents the philosophy of the author himself and is in no way constrained by the views of the sponsoring agency. Over the past two decades Dr J. A. C. Fortescue has become well known at a number of research centers throughout the world. He has pioneered the approach to environmental understanding that is comprehensively developed in this text. The limitations of traditional compartmentalized approaches are depre cated and the case is made for a holistic rethinking of basic concepts and princi ples. Landscape Geochemistry is the disciplinary outcome that gives expression to this rethinking. It may be viewed as the minimum scale of conceptual approach necessary in the environmental sciences to solve present-day problems and to exploit future opportunities."

The African continent is unique in that it has escaped widespread orogenic activity after the Pan African orogenic event. Therefore, the African Plate provides the world's best example of the relationship between extensional magmatism and structural setting. This first complete and up-to-date review, written by leading scientists, discusses the evolutionary model and offers a new and reliable basis for scientists working on plate tectonics and extensional areas in other continents.

Copper belongs to those metals whose concentrations in nature arise from a broad diversity of endogeneous and exogeneous pro- cesses, which applies to essentially all genetic classes of ore deposits. This is the first proceedings volume on copper metallogeny to cover the worldwide distribution of the four main groups of cop- per deposits, including in Part I: copper-nickel deposits with cobalt and platinum group elements; Part II: copper-molybde- num-gold deposits with silver, zinc, and lead; Part III/IV: copper- zinc-lead deposits (with silver etc.). On the occasion of the 27th International Geological Congress in Moscow, USSR, a symposium on copper metallogeny was held, dealing with metallogenesis and mineral deposits. The symposium was organized and sponsored by three international societies en- gaged in the field of ore deposits: The Society of Economic Geol- ogy (SEG), the Society of Geology Applied to Mineral Deposits (SGA) and the International Association on the Genesis of Ore Deposits (IAGOD). Invited papers were presented in four ses- sions: (1) Copper deposits in mafic and ultramafic complexes, (2) Porphyry copper deposits, (3) Copper deposits of volcanic-hydro- thermal association, and (4) Sediment-hosted copper deposits. The sessions were chaired by A. D. Genkin, A. J. Naldrett, J. D. Ridge and G. I. Gorbunov; V.1. Sotnikov, A. Soregaroli, R. H. Sillitoe and V. A. Evstrakhin; F. M. Vokes, A.1. Krivtsov, M. Solomon and N. I. Eremin; G. H. Friedrich, Yu. V. Bogdanov, A.C. Brown and F.P. Krendelev.

When an area of research is in fast growth, it often happens that no one single journal is to be found where most of the relevant publications are contained. Such is the case of the physics of intercalation compounds, a field which, by sitting at a corner point between materials science, solid state physics, and chemistry, finds its contributions largely scattered about in the literature. Given these circumstances it is of crucial interest to find a place where the most recent contributions and up-to-date referen ces can be found at once. For intercalated graphite and other similar com pounds this role has been played so far by proceedings of international con ferences, such as La Napoule (1977), Nijmegen (1979), Provincetown (1980), and Sendai (1980). The present book is an ideal continuation of this series, as it contains most of the invited and contributed papers of the Trieste International Con ference on the Physics of Intercalation Compounds, held in Trieste, Italy during the week 6-10 July 1981. The main emphasis is on intercalated graphite, though several interesting contributions deal with other materials, such as polyacetylene and transition metal compounds, or with general problems, such as two-dimensional melting. The book is divided into six sections-Structure and General Properties, Electronic Porperties, Stability and Phonons, Ordering and Phase Transitions, Magnetic Resonance, and Transport Properties-reflecting the main areas of interest, and also broadly the main discussion sessions of the Conference."

The decision of Springer-Verlag to publish this book in English came as a pleasant surprise. The fact is that I started writing the first version of the book back in 1978. I wished to attract attention to potentialities inherent in selected-area electron diffraction (SAED) which, for various reasons, were not being put to use. By that time, I had at my disposal certain structural data on natural and synthetic minerals obtained using SAED and high-resolution electron microscopy (HREM), and this stimulated my writing this book. There were several aspects concerning these data that I wished to emphasize. First, it was mostly new and understudied minerals that possess the peculiar structural features studied by SAED and HREM. This could interest mineralogists, crystallo chemists, and crystallographers. Second, the results obtained indi cated that, under certain conditions, SAED could be an effective, and sometimes the only possible, method for structure analysis of minerals. This inference was of primary importance, since fine dispersion and poor crystallinity of numerous natural and synthe tic minerals makes their structure study by conventional diffrac tion methods hardly possible. Third, it was demonstrated that in many cases X-ray powder diffraction analysis of dispersed miner als ought to be combined with SAED and local energy dispersion analysis. This was important, since researchers in structural min eralogy quite often ignored, and still ignore even the simplest in formation which is readily available from geometrical analysis of SAED patterns obtained from microcrystals."

Many interesting and perplexing questions arise in connection with the highly potassic volcanic associa- tion dominated by mafic and ultramafic rocks contain- ing leucite. Its occurrence is very restricted as compar- ed with the olivine-basalt trachyte kindred, but it is distributed at widely scattered points on all the conti- nents, and its chemical and petrographic individuality is both remarkable and constant. A considerable litera- ture is available related to the mineralogy, petrology, geochemistry, phase chemistry, distribution, and origin of this interesting suite of rocks. It seemed that there was a genuine need for a review-synthesis of all these data, which would be intelligible to a wide spectrum of advanced students and professionals in the earth sciences. The monograph may be divided into two parts. The first part consists of six chapters in which the mineralogical and chemical peculiarities of leucite- bearing rocks and their nomenclature, petrology, min- eralogy, distribution, and physical and chemical condi- tions of formation are discussed. Phase equilibria stud- ies on many leucite-bearing ternary, pseudoternary, quaternary, and pseudoquaternary joins and systems, studied by different investigators at variable tempera- tures in air, are described in the second part in Chap- ters 7 to 12. Survival of leucite and formation of pseu- doleucite is discussed in Chapter 13. Leucite-bearing synthetic and natural rock systems studied at different temperatures under variable pressures in presence or absence of water, are summarized in Chapters 14 and 15.

Analyses data on the composition, structure and formation of various petroleum hydrocarbons: the alkanes, cycloalkanes and arenes. Attention is paid to biological markers, com- pounds that may have preserved the main structural features of the original biogenic molecules. Concepts of chemical classification of crude oils are reviewed with respect to the molecular mass distribution of biological markers, and the genesis and chemical evolution of petroleum hydrocarbons are discussed.

and their identification obviates individual thermochemical studies on every genus. The stability relations among sedimentary carbonate minerals are now more or less well known. The common rock-forming minerals cal cite and dolomite are indeed stable phases in the pertinent systems. Most other carbonate minerals of similar composition which are known to occur in the younger sediments are metastable with respect to calcite, dolomite, and magnesite. This implies that the sedimentation of carbon ates is determined only in part by stability relations. Kinetic factors, which allow the formation of metastable minerals, appear to be more important. Although the diagenetic transformations leading to stable minerals take place by virtue of thermodynamic requirements, the reac tions themselves are triggered by kinetic factors as well. Some of the reactions leading from metastable to stable carbonate assemblages are susceptible to simulation in the laboratory; others (e. g. dolomitization) appear to be so slow that they can be studied only in analogous systems characterized by reasonable reaction rates. In all attempts to explain the possible mechanisms of such reactions, we must consider the crystal structures of the final products as well as of the starting materials. This is another viewpoint from which mineralogy is important to carbonate petrology, if we regard the crystal chemistry of minerals as a part of mineralogy. A certain parallelism with clay mineralogy suggests itself."

At last geochemists are offered one comprehensive reference book which gives the Eh-pH diagrams for 75 elements found in the earth's surface environment, including transuranic and other radioactive species. For each of these newly calculated diagrams short explanatory texts are added. For the first time the primary elements are considered in water with metal, sulfur, carbon, and other species as appropriate. Furthermore, based on these figures and up-to-date thermodynamic data presented in this reference, researchers can predict the behavior of elements in the surface environment. Geoscientists, chemists and environmental agencies will also benefit from several brief texts on the importance of various elements to problems of radioactive waste disposal.

In May of 1991, Victor Van Buren, who was then with Springer Verlag in New York City, asked us for timely topics in the earth sciences that would be appropriate for publication as a book. We all quickly agreed that recent interest and research activity on the role of organic acids in geological processes would make a timely book on this diverse and controversial topic. As coeditors, we outlined chapter topics for such a book that maintained a good balance between geological and geochemical interests. Specific authors were then sought for each of the chapter topics. We had exceptional success in getting leading researchers as authors, and their response was universally enthusiastic. This approach has been most gratifying in that it provides a cohesion and conciseness that is not always present in books representing compilations of papers from symposia. This book does not resolve the controver sies that exist regarding the significance of organic acids in geolog ical processes. However, it does present both sides of the controver sies in terms of available data and current interpretations. Readers may judge for themselves and envisage research necessary to resolve these controversies in the future. We thank the authors of this book for their participation, dedication, and cooperation. We are also grateful for support from Dr. Wolfgang Engel and his staff at Springer-Verlag (Heidelberg) in expediting the editing and publication of this book in a timely manner."

Earth scientists, who have worked together for 6 years in the priority pro gram "Hydrogeochemical Processes in the Hydrological Cycle Within the Unsaturated and Saturated Zones," have summarized the results of their research in this volume. This is the occasion to take stock and then look ahead. The priority program was set up by the Senate of The Deutsche Forschungsgemeinschaft in October 1981. This was preceded by lengthy and careful preparation by a Program Committee, and was finally recom mended by the Senate Commission for Joint Research in Earth Sciences. The main aim was the interdisciplinary research of geochemical processes in natural systems in the total underground water cycle, whereby water pollution was not to be considered. Officially started on 1 September 1982, the program has received a grant of DM 10. 9 Mio. from the DFG, and this has enabled it to support a total of 50 projects. Although at the beginning, practice-oriented projects, which were funded elsewhere, were not to be included, many of the results are applicable. The four categories presented were investigated with vary ing intensity. An early concentration on certain representative fields of measurement and research areas proved to be the right approach - this avoided a waste of effort in other fields. During the period of the priority program, new and topical questions arose, e. g."

Professor OTTO BRAITSCH'S Entstehung und Stoffbestand der Salz- lagerstiitten has since its publication in 1962 enjoyed a reputation as the most complete and authoritative treatment, in any language, of the geochemistry of evaporites. The issue of this translation will now make it accessible to a much wider circle of readers. The years since first publica- tion of the German edition have seen a great surge of discussion and research on evaporites among English-speaking geologists, and while BRAITSCH'S work was important to some of these it can now no longer be ignored by any. It may be worth pointing out that, title notwithstanding, this volume takes as its subject not only the salts but all evaporite minerals and rocks, but that it makes no attempt to go beyond the geochemical evidence in discussing the origin of these evaporites. The reader should not expect to find here any extensive discussion of paleogeography and stratigraphy, or even petrographic detail. Within its scope of geochemistry and mineral- ogy the coverage is extensive.

Today large numbers of geoscientists apply thermodynamic theory to solu tions of a variety of problems in earth and planetary sciences. For most problems in chemistry, the application of thermodynamics is direct and rewarding. Geoscientists, however, deal with complex inorganic and organic substances. The complexities in the nature of mineralogical substances arise due to their involved crystal structure and multicomponental character. As a result, thermochemical solutions of many geological-planetological problems should be attempted only with a clear understanding of the crystal-chemical and thermochemical character of each mineral. The subject of physical geochemistry deals with the elucidation and application of physico-chemical principles to geosciences. Thermodynamics of mineral phases and crystalline solutions form an integral part of it. Developments in mineralogic thermody namics in recent years have been very encouraging, but do not easily reach many geoscientists interested mainly in applications. This series is to provide geoscientists and planetary scientists with current information on the develop ments in thermodynamics of mineral systems, and also provide the active researcher in this rapidly developing field with a forum through which he can popularize the important conclusions of his work. In the first several volumes, we plan to publish original contributions (with an abundant supply of back ground material for the uninitiated reader) and thoughtful reviews from a number of researchers on mineralogic thermodynamics, on the application of thermochemistry to planetary phase equilibria (including meteorites), and on kinetics of geochemical reactions."

1 The content ofthis article is based on a German book version ) which appeared at the end of the year 1986. The author tried to incorporate - as far as possible - new important results published in the last year. But the literature in the field of "convection and inhomogeneities in crystal growth from the melt" has increased so much in the meantime that the reader and the collegues should make allowance for any incompleteness, also in the case that their important contributions have not been cited. This could for example hold for problems related to the Czochralski growth. But especially for this topic the reader may be refered to the forthcoming volume of this series, which contains special contributions on "Surface Tension Driven Flow in Crystal Growth Melts" by D. Schwabe and on "Convection in Czochralski Melts" by M. Mihelcic, W. Uelhoff, H. Wenzl and K. Wingerath. The preparation of this manuscript has been supported by several women whose help is gratefully acknowledged by the autor: Mrs. Gisela Neuner for the type writing, Mrs. Abigail Sanders, Mrs. Fiona Eels and especially Prof. Nancy Haegel for their help in questions of the English language and Mrs. Christa Weber for reading corrections. Also the good cooperation with the Springer Verlag, especially Mrs. Bohlen and with the managing editor of Crystals, Prof. H. C. Freyhardt, who critically read the manuscript, is acknowledged.