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    Read the following reviews on Special Publication 3

    Review published in Journal of Petrology, 41, 475-476 (2000)
    Atlas of Micromorphology of Mineral Alteration and Weathering by Jean E. Delvigne. Canadian Mineralogist Special Publication 3. Mineralogical Association of Canada (in collaboration with ORSTOM, Paris), Ottawa, Ontario, 1999. 509 pp. ISBN 0921294433 (MAC), 2709914204 (ORSTOM). US$125 (US$100 to MAC members)

    Those of us who do the sort of work with igneous rocks that demands we actively seek samples that are as close to the 'when-it-came-out-of-the-volcano' state as possible (except, perhaps, in the thermodynamic sense), need to be reminded, on occasion, that our work represents merely an end-member in the great spectrum of petrological and geochemical research into igneous rocks. For example, an igneous petrologist of geochemist might consider research into the weathering and alteration of igneous rocks as a kind of 'posthumous' study, whereas a soil scientist might describe the eruption and crystallization of magma as the birth of his or her starting material. The work of Jean Delvigne on the topic of mineral alteration and weathering forms a strong and essential bridge between the research of the petrologist and that of the soil scientist. He describes it simply as 'the point as which rocks meet the environment'.

    Delvigne's lifetime of dedicated and meticulous work has been brilliantly encapsulated in this 494-page book, meticulously edited by Robert Martin. The overall typesetting and layout is colourful, imaginative and neat, and includes 600 colour photomicrographs, carefully selected from Delvigne's collection of more than 10 000, which are clearly labelled and fully described. Like any good cook, Delvigne starts with the 'ingredients' in this case, virtually unaltered (mostly igneous) rocks, and methodically leads the reader through the various stages and degrees of alteration of their principal rock-forming minerals, using photographs, as well as colour and black-and-white illustrations combined with descriptive and explanatory text, until one arrives at the principal constituents of soil, no longer recognizable as 'rock'. This is an easy (and colourful) transition for a petrologist to follow and understand, although necessarily backwards for a soil scientist. The rock-types (and hence rock-forming minerals) covered are extensive and diverse, including picrite, komatiite, basalt, gabbro, pyroxenite, amphibolite, granite, syenite, phonolite, charnockite and carbonatite, as well as additional minerals such as garnet, staurolite, titanite and perovskite. The most common rock types (basalt, pyroxenite, gabbro, granite) appear repeatedly throughout the book in progressively altered guises.

    The book is divided into four main sections. The first, an introductory section, begins by outlining the general concepts involved in weathering processes, including a number of basic definitions, and the influence of kinetics, porosity and chemical dissolution on both petrography and geochemistry, as well as providing detailed instructions on how to sample a weathered profile (i.e. pristine bed-rock through to the resultant soil). The second section deals with the 'patterns of weathering', including clear descriptions of the degrees and patterns of weathering, as well as primary residues and secondary products. The third section covers 'alteromorphs' and includes a classification scheme that is summarized in colourful, diagrammatic form on the inside book covers for easy reference. The final section, where petrology turns into soil science, covers lithorelics, nodules and pisoliths.

    I would highly recommend this book to all libraries, to field geologists, environmental geologists, petrologists and soil scientists alike, and the quantity and quality of the book's content make it excellent value for money.

    E. A. Dunworth
    Universitetet i Oslo

    Review published in American Mineralogist 85, 878 (2000)
    Atlas of Micromorphology of Mineral Alteration and Weathering by Jean E. Delvigne. Canadian Mineralogist, Special Publication No. 3, Ottawa, Ontario, 1998, 494 p. Hardbound $125 ($100 for members of the Mineralogical Association of Canada).

    This handsome color atlas of photomicrographs is similar in some ways to color guides of petrography, heavy minerals, soils, and paleosols published in recent years, but it is in some ways unique. Particularly unique is its subject matter in the terra incognita between the traditions of metamorphic-igneous petrography on the one hand and soil micromorphology on the other hand. Although the book opens with photomicrographs of various little-weathered igneous and metamorphic rocks, most of the photomicrographs are of mineral grains more or less obliterated by weathering or hydrothermal alteration. By the end of the book, most of the photomicrographs are of pisolitic and boxwork textures formed in thich lateritic and bauxitic soils and paleosols with near total destruction of original igneous and metamorphic textures. It is thus a book that will surprise both petrologists, who labor to obtain samples without the alterations illustrated, and pedologists, who deal with less strongly developed soils and paleosols of sedimentary parent materials.

    The unique focus of this book can best be understood from the experience of its author, Jean Delvigne, who has devoted more than 40 years of detailed petrographic study to the deep weathering of igneous and metamorphic rocks of the Precambrian shields of Congo. West Africa and Brazil. The tremendous array of parent materials illustrated includes carbonatites, clinopyroxenites, nephelinites, basalts, garnet schists and amphibolites. Although emphasis is on deep tropical weathering of the kind that produces laterites and bauxites, some examples of calcretization and hydrothermal alteration are included. This book arises from the French school of pedology, which, since the pioneering work of George Millot, has had a strong emphasis on geochemical mass balance modeling and detailed petrography of thick tropical soils. In contrast, the North American-Russian school of pedology, which can be traced back to Vasily Dokuchaev and Curtis Fletcher Marbut, is more concerned with diagnostic laboratory and field properties of soils formed under much less aggressive weathering regimes on loess and till of the last glacial maximum. Delvigne introduces a whole new world of micromorphology to those accustomed to fresh rock and thin soils of high northern latitudes.

    A core contribution of this book is a deeper understanding and new terminology for pseudomorphs, which Delvigne restricts only to the replacement of euhedral mineral grains by other minerals. As we all know, most mineral grains are not euhedral, and when anhedral grains are replaced Delvigne suggests the term alteromorph. The patterns of boxwork replacement, altered-mineral extensions from grains, irregular voids, buckling of phyllosilicates, and marginal alterations are all documented in detail. The new terminology proposed is workable, but somewhat cumbersome in its use of hyphenation. For example, a phanto-alteromorph is a grain with ghostlike remnants of one alteration mineral within a groundmass of another alteration mineral. Why not abbreviate this to "phantalteromorph" or even "phantomorph" ? Despite this quibble, I think the 18 new terms introduced, and handily reprinted inside each cover, are much needed. The overall effect however, can be daunting in combination with equally arcane terminology from mineralogy (rinkite, mosandrite), petrology (lujavrite, glimmerite), pedology (alloterite, isalterite), and soil micromorphology (gefuric, inaulic). I had trouble finding some of these terms in other reference works, and not all were included in the glossary. In some cases, usage in this book is subtly different from that of others. Lithorelic (spelled lithorelict by Brewer) is used here only for relatively unweathered rock fragments, which when replaced by alteration minerals become alterorelics of Delvigne. In Brewer's original terminology, these would have remained lithorelic(t)s as long as some original rock texture was preserved. Such nuances of past, current, and alternative usages are not discussed in this book, which aims at advancing a core of new and some past terminology.

    Finally, the book is unique in many aspects of its presentation. The full color photomicrographs are dazzling, and convey well the beauty and variety of the material. Detail and clarity of the images reveals the charming intricacy of concrete examples. The text figures also are in bright cartoonlike colors, which aids considerably in conveying complex patterns of alteration. Color has also been used to indicate chapters by color-coded thumb tabs visible as bands on the trimmed page ends. Different color bands and colored text are used to highlight and differentiate introductory text, definitions, examples, and discussion. I found most of this a distraction rather than a help. The orange introductory phrase or word to figure captions was often difficult to read, and I found myself wondering at times is that dark purple of dark blue text? Nevertheless these various devices give a delightful air of creative play and the overall effect is visually stunning.

    This is an important book chiefly because there is nothing else quite like it. It succeeds in demonstrating that there is a lot more to the weathering of high temperature minerals than is widely appreciated. Any serious mineralogist should at least press for local library access to this book. Considering the lavish production in full color, I consider it excellent value for money.

    Department of Geological Sciences
    University of Oregon
    Eugene, Oregon 97403-1272, U.S.A.

    Review published in mineralogical magazine 64, 369-370 (2000)
    Delvigne, J.E. Atlas of Micromorphology of Mineral Alteration and Weathering. The Canadian Mineralogist, Special Publication 3, 1998. xvi + 495 pp. Price (hardback) $125 (US) $170 (CDN). ISBN 0-921294-43-3.

    This book is published by the Mineralogical Association of Canada in collaboration with ORSTOM (Office de la Recherche Scientifique et Technique Outre-Mer). It is thus fitting that Prof. R.F. Martin, editor of Canadian Mineralogist, should write a 'Preamble', in which he notes that this book forms a bridge between the fields of classical mineralogy and soil science. Because of the much increased interest in 'the environment', this cross-fertilization of ideas is becoming more necessary than ever. This is very much a book on the weathering of igneous and metamorphic rocks in tropical climates which the author has studied since 1956.

    The text is divided into four parts: 1 - General Concepts; 2 - Patterns of Weathering; 3 - Alteromorphs; and 4 - Lithorelics, Alterorelics, Nodules, Pisoliths. The book is thus organized such that it progresses from the early signs of weathering, as indicated by such features as alteration along cleavages and micro-fractures, through to the most extreme stages of weathering where evidence for the nature of the original rock has almost completely been lost.

    Part 3 is the longest section of the book and it was here we encountered a nomenclature of alteration products completely new to us. This is an extension of a nomenclature previously published by the book's author and is based on the degree of retention of the original shapes and volumes of the altered minerals, with qualifiers describing porosity and new minerals filling spaces for example. This can lead to some quite awful names, such as 'cumulo-meta-alveoporo-glomero-septo-alteromorph after plagioclase' (p. 328). The justification for such a nomenclature is not entirely made clear when descrition and illustration with figures and photographs, in which this book excels, would be more than an adequate substitute.

    The book contains 610 colour photomicrographs, mostly from the collections of the author and from materials collected by him in the Ivory Coast and in Brazil. Photographs are mostly printed to a standard 120 X 80 mm size and, on the whole are of very high quality, particularly considering that sections of weathered material are not always easy to make. The author apologizes for some of the older plates which could not be re-photographed and are, he feels, not as high quality as the more recent pictures. This is not really evident from studying the book and it becomes something of a challenge to identify the ones he is referring to. One minor criticism we would make is that most of the feldspars, photographed at or near extinction with crossed nicols show a rather brownish colour, somewhat similar to that shown by moderate dispersion of the refractive indices. It is surprising that this was not corrected at the printing stage.

    Six magnifications have been employed in reproducing the plates - X 17, X 27.5, X 44, X 77, X 110 and X 176. The figure given beside each plate refers to the magnification of the objective used, not the total magnification, but a scale graduated in tenths of a millimetre is also shown by each picture. Along the edges of each plate is a grid, like that on many maps and plans, to permit easy reference to part of a plate in the accompanying text. This is an excellent idea, but is in fact rarely used.

    Overall, this is a very high quality book, produced to the highest standards and is deserving of consultation by everyone in the Earth and Environmental Sciences who is interested in the tropical weathering of igneous and metamorphic rocks, or in the nature and mineralogy of soils in such areas. Much teaching of Soil Science takes place in Geography Departments and rarely involves studies using a petrological microscope. This book is therefore a timely reminder to mineralogists and petrologists of the importance of weathering in the humid tropics and, hopefully, will encourage physical geographers to make more use of the petrological microscope in describing weathered rocks. The author and the publishers are to be commended in producing an important inter-disciplinary text.

    W.S. Mackenzie and A.E. Adams

    © 2006 Mineralogical Association of CanadaLast update 2014-02-05