More related to mineralogy

Over the last several decades, the number of people who are actively involved in the hobby or science of mineral collecting has grown at an increasing pace. In response to the growing demand for informa tion which this large and active group has created, a number of books have been published dealing with mineralogy. As a result, the reader now has a choice among mineral locality guides, field handbooks, photo collections, or books dedicated to the systematic description of minerals. However, as interest in mineralogy has grown, as collectors have become increasingly knowledgeable and aware of mineralogy in its many facets, the need for more specialized information has also grown. Nowhere is this need greater than in the subject of the fluorescence of minerals. The number of collectors who now main tain a fluorescent collection is substantial, interest is constantly increasing, and manufacturers have recently responded by the intro duction of new ultraviolet equipment with major improvements in utility and performance. Yet when the collector searches for any information on this subject, little will be found. He or she will seek in vain for the answers to questions which present themselves as in terest in fluorescent minerals grows and matures. Which minerals fluoresce? Where are fluorescent minerals found? What makes a mineral fluoresce? Why does ultraviolet light produce fluorescence? What is an activator, and how does it contribute to fluorescence? On these matters, the available mineralogy books are largely silent.
The problem of time-and strata-bound formation of ore deposits has during the past decade become one of the most debated topics in cur rent international discussion. Due to the amazing results of modern mineral exploration and world-wide geophysical research, the mutual relationship between the complex geological history pf a crustal seg ment and the development of distinct metallogenic provinces (ore belts) has received much interest. Reviewing the earth's history in this light one can now recognize metallogenic epochs even of global range which document the existence of world-wide time-bound ore enrich ments. The knowledge of these metallogenetic processes has been growing step by step for several decades. It began with simple observations and sceptic interpretations, which at first threw heretical spot lights on to the edifices of the prevailing theories on granitic differentiation as the favoured source of ore deposits. It was obvious that the new ideas at first referred to ore enrichments in sedimentary sequences, nowadays summarized under the term strata-bound, and mainly interpreted as stratiform or sedimentary ore deposits. Moreover, the modern term "strata-bound" also includes ore mineralizations which are bound to distinct units of layered (intrusive or extrusive) igneous complexes as a general descriptive term without genetical restriction! Albert Maucher is one of the representatives of the initial era who discussed these genetical questions critically in the decade before the 2nd World War.
After the spectacular successes of the 1960's and 1970's, the mineral exploration business is at a crossroads, facing uncertain t:imes in the decades ahead. This situation requires a re-thinking of the philosophy guiding mineral exploration if it is to emulate its recent performance. The ma:i. n argument of a previous volume titled "Designing Opt:lmal Strategies for Mineral Exploration", published in 1985 by Plenum Publishing Corporation of New York, is that a possible answer to the challenge facing mineral explorationists lies in the philosophy of opt:irn1zation. This new approach should help exploration staff make the best achievable use of the sophisticated and costly technology which is presently available for the detection of ore deposits. The main emphasis of the present volume is placed on the mathematical and computational aspects of the opt:irn1zation of mineral exploration. The seven chapters making up the ma:i. n body of the book are devoted to the description and application of various types of computerized geomathematical models which underpin the optimization of the mineral exploration sequence. The topics covered include: (a) the opt:lmal selection of ore deposit types and regions of search, as well as prospecting areas within the regions (Chapters 2, 3, 4, 6), (b) the designing of airborne and ground field programs for the opt:lmal coverage of prospecting areas (Chapters 2, 3, 4), (c) delineation and evaluation of exploration targets within prospecting areas by means of opt:irn1zed models (Chapter 5).
This book provides an introduction into the mechanics of faulting in the brittle crust of the Earth. It developed from my annual two-semester course on tectono mechanics for graduate students of engineering geology and of rock engineering at the Technical University of Graz (Austria). In this course, it is not my task to present a broad exposition and geometrical description of geological structures, but rather to focus on the mechanical processes that produce the structures. Although this was also the aim of my former book "Mechanics of Tectonic Faulting - Models and Basic Concepts" (1988, Elsevier), henceforth referred to as MTF, the present book is different in organisation and content, in order to meet the requirements of the courses and to include more recent developments. Instead of following the traditional subdivision into extensional, compressional and strike-slip faulting, the presentation focuses on mechanical aspects of tectonic faulting that are common to various, or even all types of tectonic faults in the brittle regime. In this way, geometrically disparate or dissimilar fault structures may be revealed as closely related by the underlying mechanical process, and complex structures may be better understood. It may be useful to indicate how the chapters in the book are organised. The first three chapters are an introduction to rock mechanics, tailored to applications in geology. It also presents the extremely useful graphical method of Mohr's stress circle, which is freely used throughout the book to keep the mathematics to an absolute minimum.
The role played by earth sciences in the scientific community has changed considerably during this century. Since the revolutionary discoveries of global processes such as plate tectonics, there has been an increasing awareness of just how fundamental many of the mechanisms which dominate in these processes depend on the physical properties of the materials of which the earth is made. One of the prime objectives of mineral sciences is now to understand and predict these properties in a truly quantitative manner. The macroscopic properties which are of most immediate interest in this context fall within the conventional definitions of thermodynamics, magnetism, elasticity, dielectric susceptibilities, conductivity etc. These properties reflect the microscopic contributions, at an atomistic level, of harmonic and anharmonic lattice vibrations, ionic and electronic transport as well as a great variety of ordering and clustering phenomena. The advances made by solid state physicists and chemists in defining the underlying phenomena lnvolved in the thermal evolution of materials have stimulated major new research initiatives within the Earth Sciences. Earth Scientists have combined to form active groups within the wider community of solid state and materials scientists working towards a better understanding of those physical processes which govern not only the behaviour of simple model compounds but also that of complex materials like minerals. Concomitant with this change in direction has come an increasing awareness of the need to use the typical working tools of other disciplines.
This volume illustrates some of the significant aspects of magmatic activity from Devonian (408 million years ago) to early Permian (270 million years ago) times in SW England. This period covers the progressive development of the Variscan mountain-building episode, from initial basin formation to final deformation and the subsequent development of a fold mountain belt - the Variscan Orogen. Both extrusive (volcanic) and intrusive (plutonic) rocks are found in the orogen, and chart the various stages of its magmatic development. The sites described in this volume are key localities selected for conservation because they are representative of the magmatic history of the orogen from initiation to stabilization. Some of the earliest volcanic activity in the Devonian is represented by submarine basaltic and rhyolitic lavas developed in subsiding basins, caused by the attenuation of the existing continental crust. In some cases, extensive rifting and attendant magmatism produced narrow zones of true oceanic crust, whereas elsewhere basaltic volcanism is related to fractures in the continental crust at the margins of the basins. After the filling of the sedimentary basins, and their deformation caused by crustal shortening (late Carboniferous Period), further activity is manifested by the emplacement of the Cornubian granites and later minor basaltic volcanism in the early Permian. Accounts of the constituent parts of this history have enriched geological literature from the nineteenth century onwards, and have contributed to the advancement and understanding of magmatic and tectonic processes.
This book is intended primarily for exploration geologists and post graduate students attending specialist courses in mineral exploration. Exploration geologists are engaged not only in the search for new mineral deposits, but also in the extension and re-assessment of existing ones. To succeed in these tasks, the exploration geologist is required to be a "generalist" of the Earth sciences rather than a specialist. The exploration geologist needs to be familiar with most aspects of the geology of ore deposits, and detailed knowledge as well as experience play an all important role in the successful exploration for mineral commodities. In order to achieve this, it is essential that the exploration geologist be up to date with the latest developments in the evolution of concepts and ideas in the Earth sciences. This is no easy task, as thousands of publications appear every year in an ever increasing number of journals, periodicals and books. For this reason it is also difficult, at times, to locate appropriate references on a particular mineral deposit type, although this problem is alleviated by the existence of large bibliographic data bases of geological records, abstracts and papers on computers. During my teaching to explorationists and, indeed, during my years of work as an explorationist, the necessity of having a text dealing with the fundamental aspects of hydrothermal mineral deposits has always been compelling. Metallic mineral deposits can be categorised into three great families, namely: (I) magmatic; (2) sedimentary and residual; (3) hydrothermal.
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