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July-August 2016

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A Geologist Speculates on Gemstones, Origins of Gas and Oil, Moonlike Impact Scars on the Earth, the Emergence of Animals and Cancer by John M. Saul. Les 3 Colonnes, Paris, France. 159 pages; 2014; €28 (softbound).

John Saul is an American geologist, currently living in France but who has spent most of his working life in East Africa. Through an initial search for beryllium, his interest turned to gemstones, and he has since been heavily involved in the discovery and development of gem mines, particularly rubies, tsavorite, and tanzanite.

Two things strike the reader immediately upon opening this book: it is highly speculative and also highly original. That is apparent in the preface, in which Dr. Saul introduces the reader to the “organic odor” of gemstone deposits (p. 11); the possible inorganic origin of petroleum; the traces of meteoric impacts on Earth; the codependence (my term) of gemstone deposits and multicellular life; and, finally, “three life forms that might arguably have escaped the workings of Darwinism” (p. viii).

The book is divided into five more-or-less independent sections: (1) Gems, (2) Deep Carbon and Outgassing, (3) Early Impact Scars, (4) Animals and Cancer, and (5) The Ends of Darwinism. In the table of contents (actually at the front, which is unusual for a book published in France), each section has a small preface of its own outlining the basic thesis, then a large number of smaller subheadings developing Saul's argument. In the preface for “Gems,” for example, he states (p. iii): “Very few deposits of transparent gems, with the exception of diamonds, were formed during the first 80 percent of our planet's history.” He goes on to elaborate this point in the “Gems” section itself, ending with the speculation (p. 2) that many “crystalline colored gemstones” (CCGs) were created during the formation of the supercontinent Gondwana, via heat generated through rotational continental friction. Others, such as blue-green-yellow sapphires, were generated later during the Gondwana breakup, in association with “large quantities of mantle-derived CO2” (p. 29). He notes also that the formation of CCGs coincided with the so-called Cambrian Explosion of multicellular life and that many gem deposits are associated with a peculiar organic smell.

That mantle-derived CO2 reappears in the second section in which Saul speculates (p. 37) on an inorganic theory of petroleum formation, speaking of an “outgassing” planet, in which methane and carbon dioxide originating at great depth and percolating upward slowly could polymerize, producing non-biogenic petroleum and perhaps even coal. Bacteria from upper regions could imprint such deposits biologically later, giving the impression of a biogenic origin.

In Section 3, Saul addresses the apparent absence of evidence for massive meteoritic bombardment of Earth as observed on the Moon, Mars, or Mercury. His contention is that the evidence is indeed present but has not been interpreted properly and has been overshadowed by the notion that it has been removed by subsequent erosion and tectonic plate movement. He presents evidence that continental cratons thousands of kilometers across may be attributed to gigantic meteorite strikes during the period known as the late heavy bombardment (LHB), 4.1–3.8 billion years ago, and he postulates that cooling of meteorite-induced melt may have produced dense rock that sank into lighter rock and changed the patterns of subduction that may have gone before. In a sense, he is challenging some of the aspects of uniformitarianism that has held sway for much of the last century. He is also saying that the very deep fracture patterns created by those LHB impacts persist to this day, despite tectonic movement, and could control the formation of gem deposits and allow for the upward migration of fluids and gases.

Section 4, “Animals and Cancer,” speculates on the making of multicelled animals—perhaps via the need to shed oxygen that resulted in a sticky collagen coat that made unicellular animals stick together. Another undesirable element is calcium, but shed calcium might stick to the outside and create a shell that could prove useful. The cancer part suggests that some cells might lose their ability to deal properly with oxygen and resort to the ancient method of fermentation instead, becoming independent of the parent multicellular structure.

Section 5, “The Ends of Darwinism,” is not a rejection of Darwinian theory but a suggestion that humans might rise beyond it on a philosophical plane, and that organisms living in a totally unchanging environment (perhaps the deepest Earth) would not change because there was no need to.

The book, although concise, has some intensely complicated original reasoning, and I am sure that Saul could, with cause, accuse me of misinterpreting or oversimplifying what he has written—certainly in a review of this length. It is fair to say, however, that he has collected and interpreted a massive amount of information in an original manner. Each assertion is backed up with reference to other works—128 references in Section 3 alone—and there is a 19-page bibliography.

Although each section can be read and treated independently, at the end the reader realizes that everything—gemstones, odd smells, planet outgassing, deep impacts, and multicellular animals—can be tied together in a comprehensive way. This is a book to make one think.

Minéraux de Bretagne (Minerals of Brittany) by Louis Chauris (in French). Les Éditions du Piat, Saint-Julien-du-Pinet, France. 335 pages; 2014; €35 (softbound).

Brétagne, or Brittany, is the long peninsula that juts from northwest France between the English Channel and the Bay of Biscay. The Armorican Massif, a peneplained area of schists and gneisses ranging from the Precambrian to the Carboniferous, overlaps the entire region. I must admit that little in my experience had alerted me to many notable mineral specimens from this part of France, but apparently there are—and the photograph of a gorgeous 1.5-cm cassiterite crystal on page 125 bears that out.

In the table of contents (hidden between pages 330 and 332—an idiosyncrasy found often in French publications), Louis Chauris lists 368 mineral species found in the region, but he gives another four (goldmanite, fougèrite, trébeurdenite, and mössbauerite) in Annex 2, titled “Omitted Minerals.” That's a lot of minerals for an area only slightly larger than the state of Maryland (34,024 km2 versus 32,133 km2), but a closer reading of the text reveals that some are reported only rarely or from single finds in the past. For example, voglite was noted only once during prospecting for uranium in 1957; paracoquimbite is known only from traces in anglesite; and eskmoite, gustavite, and heyrovskyite are listed as names with no further explanation.

The book has a laudatory preface by Yves Cyrille, director of the Maison des Minéraux (House of Minerals, a museum at the tip of the peninsula), and a foreword by Chauris describing the genesis of the work over many years and the encouragement by others to continue. It continues with a section, “Reflections on a Half-Century of Professional Life: Former Celebrities … or History and Legend,” in which he describes first the significance of andalusite (variety chiastolite) to the region and its association with the term macle (a voided lozenge) in heraldry. The croisette de Bretagne (little cross of Brittany), similar to the chiastolite graphite cross, appeared on the coat of arms of the powerful Rohan family as far back as the year 1222. He next pays homage to mineralogists and collectors of influence in the area, then gets into economic minerals and geology. Brittany has andalusite, iron, lead, zinc, tin, antimony, tungsten, gold, silver, and uranium in varying quantities, but above all it has kaolin. The last is easily seen in the book itself, for although it has a soft cover and is not large (24 × 12 × 2 cm), it weighs close to 1.5 kilograms. That's a lot of kaolin to hold while reading.

Although the book lists 374 minerals, Chauris takes a few paragraphs to say how difficult it is to specify precisely how many there are. He estimates approximately 400 but says that the task of sorting them out is un casse-tête (a head-breaking puzzle) because of the number that have been renamed or discredited through the years (landevanite—now montmorillonite; bavalite—now chamosite; junckerite—discredited, and so on). Some have yet to be accepted. He also laments that mineral nomenclature has become so complicated—something with which, as a collector, I have to agree. Eight minerals have been discovered or described first from Brittany: laumontite, plumbogummite, bertrandite, natrodufrénite, lulzacite, fougèrite, trébeurdenite, and mössbauerite.

The geological section is short, running briefly through the Icartian, Cadomian, and Hercynian (Variscan) orogenies at about 2,000, 660, and 340± million years respectively to produce the current mix of igneous, metamorphic, and sedimentary formations that make up the Armorican Massif. Some parts are spectacular. The northern section of the peninsula between Plestin-les-Grèves and Louannec isn't called “The Pink Granite Coast” for nothing, but the whole is again very complicated.

All of the above, including photographs of people, equipment, and historical mines, occupies a mere 31 pages. The rest of the text, to page 335, is filled with descriptions of minerals and their sources, plus a few add-ons such as an epilogue, two appendices, the table of contents, and a long list of bibliographic references (675, to be precise).

Chauris is a scientist. He is now eighty-five, but he was director of research at the Centre National de la Recherche Scientifique (National Centre of Scientific Research) and a research associate at the Centre de Recherche Bretonne et Celtique (Breton and Celtic Centre for Research). As a scientist, he organized this part of his book with precision, beginning with native elements (12), sulfides and sulfosalts (94), halides (7), oxides (55), and so on down the line to end with silicates (113), all neatly divided into neso-, soro-, and cyclosilicates. Where possible, each mineral is accompanied by a locality map indicating the appropriate mine or mines and by a series of photographs, most taken by accomplished mineral photographer Louis-Dominique Bayle, owner of the publication Le Règne Minéral (The Mineral Kingdom). Most mineral descriptions are given with formula, crystal system, density, and hardness, followed by locality information and references. A few are listed by name only, without further comment. The listing is of minerals that have been reported at some point, not necessarily those that are collectible or of economic importance. Appendix 2 lists the four noted above as omitted, but Appendix 1 is perhaps a little controversial, as it lists 37 minerals also found in the slag heaps from lead mining activity in the region of Poullaouen, smack on the center line of the peninsula. As slag minerals, their admission may be a matter of personal preference, but they would certainly be attractive to some members of the community, for they are suitable primarily for micromounts.

The epilogue is in part an apology for the “incompleteness” of the mineral count, and a note of hope that a region so barren of mountains, so covered with vegetation, and yet so complicated, may still yield many more species.

In terms of the book itself, I have only two complaints. One is that although there are many locality maps, there is no introductory map of the entire region. I find it strange that so many publications fail to provide an orientation map of the entire area under consideration. The second is picky, but annoying. Each mineral description is followed by a gap and a thin line separating it from the one following. The problem is that the line does not separate; it is placed so close to the next title that it seems to truncate it at the top. The effect is hard on the eyes and irritating after a few pages. Other than that, this is a fine compendium of the minerals of Brittany, written by a professional, and is truly informative. It is worth the cost.

Schwarzwald—Lagerstätten und Mineralien aus vier Jahrhunderten. Band I—Nordschwarzwald und Grube Clara. (Black Forest—Mineral Deposits and Minerals for Four Centuries. Volume I—Northern Black Forest and Clara Mine) by Gregor Markl. (in German). Edition Krüger Stiftung, Bode Verlag; 672 pages; 2015; €75 (hardbound).

Reviewing a book with almost 700 pages is a daunting task. It begins with getting it home on the plane and ends when you have worked your way through hundreds of pages and finally submitted the review to the editor. In my case, I had to bring not only one but three heavy, large-format books home that I had picked up at the 2015 Munich Show—a challenging task to divide the weight of the books between checked and carry-on luggage to avoid excess luggage fees from relentless check-in personnel.

The Black Forest is a mineral-rich region familiar to most Rocks & Minerals readers; Wolfgang Wendel recently introduced the Clara mine and its minerals in the January/February 2015 issue. However, more encompassing literature on the entire region goes back more than two decades to Kurt Walenta's 1992 book Die Mineralien des Schwarzwaldes (Minerals of the Black Forest). For those who can read German, literally hundreds of articles have been written during the past decade or two, mostly in various German-language mineral and collectors' magazines. That brings me straight to the references listed in Gregor Markl's book (yes, I sometimes read a book starting in the back): six pages with three columns each and printed in a very small (about 2-mm) font, 525 references in total. But more on that later.

The book starts with a preface by Dr. Erika Krüger, head of the Krüger Foundation that underwrote the production of the book, followed by a 2-page table of contents. Next Markl, a professor of mineralogy at the University of Tübingen, Germany, introduces the book with a special thanks to undergraduate and doctoral students whose scientific research in the Black Forest he had mentored. The book is a culmination of ten years of research. One individual cannot complete a book of this magnitude, and it is not surprising that Gregor needs a full page to acknowledge everyone who was involved in the completion of this book on various levels.

With all the formalities completed, we head into the chapter titled “Introduction into the Geology and Mineralogy of the Black Forest.” Fifteen pages, well illustrated with photos, maps, and cross sections, set the stage for a closer look at the types of mineralization occurring in the region. Markl differentiates three types of magmatic/hydrothermal events according to their geologic age, from Carboniferous/Permian, Jurassic/lower Cretaceous, and Tertiary, and a fourth mineralization in the surrounding Mesozoic sediments that formed the various “Types of Mineralizations” that we get introduced to in the following 23 pages. To get a handle on the various minerals and processes, the four mineralizations are individually subdivided further according to their mineral associations and the mines where they occur. The next chapter, “A Brief Geochemistry of the Most Important Mineral Groups,” shows the handwriting of a geochemist and gets quite scientific. The mineral species are individually described, with their descriptions explained by ternary diagrams, phase diagrams, and tables—a considerable amount of information for the collector to digest. The formation of minerals through weathering, a process environmentalists especially are interested in nowadays, and a brief chapter on minerals formed as a result of the ancient mining technique of fire setting leads to “A Very Brief History of Mining and Mineral Trade.” Markl rightly states that much has been published about the mining history of the Black Forest that dates back to the Neolithic Period (about 5000 B.C.). Celts and Romans left traces of mining activity, and mining through fire setting, a common practice in the Dark Ages in Central Europe, presumably was applied for the first time in the Black Forest. Markl keeps the historic part brief, but it is interesting how he weaves the evolution of the exchange of specimens between scientists into the emerging mineral-specimen trade. The introductory chapters conclude with a 2-page chapter about the “Economic Significance of the Black Forest Deposits.”

The present volume is the first of three and focuses on the northern Black Forest. Markl starts with a statement (p. 78) that the “northern Black Forest has only very few important mineral deposits compared to the central and southern Black Forest” and shows an overview map on the opposite page covered with about fifty red dots, one for each deposit and numbered in the order in which they are described individually in the next almost 300 pages. All are well written with brief introductions to the local geology, concise histories of the deposits and mining activities, important mineral species, and often a list of minerals of the deposit. All are lavishly illustrated with photos of the deposit (many historic and modern), large photos of macro- and micro-sized minerals, detailed maps, historic labels, historic maps and mine layouts, historic documents … you name it. Among these localities are the well-known Käfersteige mine, abandoned in 1997, that worked one of the largest hydrothermal veins in Central Europe; the famous Neubulach district, mineral specimens of which can be found in Goethes' collection; the Lierbachtal agate deposit, with its colorful quartz variety; the Freudenstadt district, where mining dates back to the seventeenth century; the Oberkirch district with its fantastic fluorite; and many smaller deposits with mining activities going back in some cases to medieval times.

By page 378, Markl has left the northern Black Forest and headed south to the Clara mine in the central Black Forest. May I remind you that the Clara mine can put forward a few superlatives? With more than four hundred mineral species, Clara is the European locality with the most minerals, and it takes fifth place in the ranking of the most mineral-rich localities worldwide. If this does not warrant a separate chapter in the book, what does? Markl provides an introduction to the history of its mining activities, use of the ore, geology, and mineralogy and the various mineral associations. An impressive 250-page-long photo gallery of the Clara mineral species from agardite to zincolivenite, unknown mineral species, and historic labels is presented in mostly large and colorful photos.

This leads to the book's photography, which deserves special mention and includes a stunning eighteen hundred photos in total. A modest remark on page 20 reveals that almost all specimens pictured are from Markl's own collection. Well-known mineral photographer Jeff Scovil spent considerable time at Markl's home in Tübingen documenting the extensive collection, and one of the most accomplished German photomicrographers, Matthias Reinhardt, contributed most of the photomicrographs. Numerous other photographers provided spectacular underground photos. Kudos to publisher Rainer Bode for the layout; it is well done with a pleasant-to-read font and a clear, uncluttered layout.

We are nearing the end of the book. A 2-page mineral list with species names and chemical formulas, an extensive reference list, a short biography of Markl, and—very helpful for a book of this size—a useful index fill the last pages.

The referencing style used in the book is rather unique. The entries are in alphabetic order and numbered from 1 to 525. Although not uncommon to use numbers for references in a text instead of more traditional styles (e.g., author's last name and year), the individual chapters are not referenced in the text, but the sources are listed as a compilation of numbers at the end of each chapter. This style may have saved some extra pages, but it makes it virtually impossible to identify individual references of a chapter. Incomplete references (e.g., #171) are not uncommon; some references are missing (e.g., Wendel 2015). The book certainly would have greatly profited from a more thorough editing process.

Don't get me wrong, Markl's book is excellent not only for collectors of Black Forest minerals and those who collect classic German localities, but it is also a great mineral book … period. When all three volumes are available, the set will be the ultimate reference on the minerals and localities of the Black Forest. Volume 1 is an excellent addition to any mineralogical library, just make sure that your bookshelf can handle the weight: 3.3 kilograms. And don't forget, this is just one volume—with two more to come you are looking at a load of about 10 kilograms on your bookshelf in the near future.


Wendel, W. 2015. The Clara mine, near Wolfach in the Black Forest, Germany: From the myth of the “golden calf” to modern mining. Rocks & Minerals 90 (1): 34–49.

Turmalin, Faszinierende Kristalle mit Phantastischen Innenwelten: Tourmaline, Fascinating Crystals with Fantastic Inner Worlds by Paul Rustemeyer, bilingual (German/English). Verlag Dr. Friedrich Pfeil, Munich, Germany. 272 pages; 2015; $90 (hardbound).

If black, non-transparent tourmalines are cut into thin plates and these plates are ground down to a fraction of a millimeter, the resultant slices become transparent and show complex growth structures combined with various types of color zoning. This book by Paul Rustemeyer consists mainly of very high-quality color photographs that depict the internal world of tourmalines as revealed through such slices. Supplementing these views are additional photographs taken from somewhat thicker slices of transparent, gem-quality tourmalines.

Rustemeyer previously published a book in German (2003) that likewise focused on tourmaline, and ensuing years have seen notable demand to have the book made available in English as well. However, instead of preparing a simple translation, Rustemeyer and his publisher decided to produce a separate bilingual book with texts kept “as short as possible” (p. 6), texts that emphasize the role of tourmalines as natural art objects. The photographic record of that natural artwork is termed “TourmalineArt” by the author.

The photographs offered have as their primary subjects cross sections cut perpendicular to the c-axis of the tourmaline crystals. Series of such slices along the c-axis show the complete growth history and three-dimensional color zoning of the crystals, as related to growth sectors of the main crystal forms such as the pedion in combination with various prisms and pyramids.

After an introductory chapter on the concept of TourmalineArt, the book presents four chapters detailing mineralogical and gemological properties of the different tourmaline-group mineral species. These chapters also delve into the color varieties of blue, green, red, orange, and yellow gem-quality transparent tourmalines. Short descriptions of crystal structure, chemical properties, color and its causes, crystal growth in pegmatite dikes, and crystal morphology and habit are provided.

The four chapters dedicated to mineralogical or gemological properties are followed by eight chapters depicting special growth phenomena observed in tourmalines and incorporating short, but significant, explanations of the observed patterns. These chapters cover topics such as rim structures, skeleton-like structures, delta structures, dislocations, and parallel aggregates, as well as structures caused by natural healing and corrosion processes. Certain of the eight chapters then close with several pages devoted to additional photographs of growth phenomena and color zoning, generally at high magnification but without figure captions or any explicit connection to the preceding text. These pages are presumably offered as an “aesthetic” part of the book.

In general, Rustemeyer and his publisher met the challenge of preparing a bilingual book intended for a diverse audience (i.e., accessible not only to the reader with mineralogical background, but also to the gem and mineral collector and to those with a more generalized artistic interest). The heart of the book consists of the excellent photos of various growth structures combined with different forms of color zoning, the study of which will be enjoyable and informative at all levels. However, some aspects of the layout and presentation could have been improved.

Photographic pages without figure captions remain largely shrouded in mystery, and although in a few instances prior discussions may hint that detailed pictures of described phenomena will follow on the more “aesthetic” pages, at least some of these hints are erroneous. On page 96, for example, readers find pictures of five different tourmaline cross sections with a statement that detailed photographs are found on page 121, but that particular page consists only of a single enlarged photograph.

Furthermore, the mixture of German and English in some of the figure captions is not always clear. If the two languages are placed in visually separated blocks that together comprise a single caption, there is no confusion. In contrast, where the German and English portions are conjoined, the reader of only one language must struggle to avoid missing relevant information. Similarly problematic is when dimensions in a caption are given in only one language, and even when both languages are provided, the dimensions given in German may differ from those given in English (e.g., in some of the captions on pages 22, 228, and 242).

As to the broader issue of the English translation itself, it will be immediately apparent to a native speaker that the book might have benefited from further review focused on this aspect. The terminology and diction are in places atypical and awkward, and there exist instances where the translation is incomplete. One important example of such unfortunate intermixing of German and English occurs in the mineralogical overview table of the tourmaline group on page 28. Nonetheless, given that the publication is beautiful and generally understandable, it should be a valuable addition to the libraries of those fascinated by all that tourmalines have to offer.


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