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May-June 2018

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Collector's Guide to Silicates: Orthosilicates by Robert J. Lauf. Schiffer Publishing, 4880 Lower Valley Rd., Atglen, PA 19310; www.schifflerbooks.com. 240 pages; 2017; $45 plus shipping (hardbound)

I am pleased to recommend this authoritative and affordable guide to the mineralogy of an important group of common silicate minerals, the orthosilicates. Any serious beginning or advanced mineral collector should own this book and use it.

This volume contains descriptions of the subset of silicate minerals with atomic structures characterized by tetrahedral-shaped silicate groups (SiO4) that do not link directly to one another by sharing oxygens. Although adopting this general selection criterion, author Robert J. Lauf also includes a few non-silicate minerals that share the structural pattern of one of the orthosilicates. For example, the borate mineral sinhalite has an atomic pattern similar to the silicate mineral olivine and is discussed because sinhalite was confused with olivine until chemical analyses and X-ray study of individual samples revealed their significant compositional differences. The hydroxide mineral katoite is included in the garnet supergroup section as an endmember in the hydrogrossular series. These examples remind us that nature doesn't always fit into simple classification categories and encourage the reader to extend the principles about atomic structures and bonding demonstrated by these silicate compounds to non-silicates.

What serious collector who possesses one or more large well-formed crystals of any of the common orthosilicate minerals (the garnets, olivine, staurolite, kyanite, andalusite, vesuvianite, zircon, or topaz) would not want to know more about them? This book helps the collector also learn some mineral science as well as admire the aesthetics of the orthosilicate minerals through a rigorous narrative that makes the topics discussed accessible to a wide range of readers. The extent of technical expertise demanded by some of the content (narrative and illustrations) will require some readers who do not have formal training in chemistry and crystallography, yet were attracted by this book's excellent assortment of photographs, to brush up on topics such as Miller indices, crystallographic reference axis sets and forms, mole percent, molecular components of solid-solution series, some technical geologic terms, and the conventions of mineral formulas and their meanings. Fortunately, references to relevant technical literature are embedded in the narrative so that individuals can acquire the background, on their own as necessary, to understand some of Dr. Lauf's points. The list of selected references from the nearly three hundred years of relevant scientific publications contains many “classic” papers and provides a good introduction to mineral science for the serious collector.

The production quality of the profusely illustrated book is excellent. The paper is of high quality, and the binding allows the book to lay flat when open and will survive even with heavy use. The type fonts are clean and very readable; the use of color and bolding in titles, headings, and subheadings is quite effective. The size of pages allows for several color photographs per page, each large enough to illustrate very well the mineral species and its diagnostic external characteristics. Excellent color photographs with scale and locality information accurately demonstrate the range of colors, lusters, and shapes of each mineral species included. Figure captions contain the basic information that a serious collector will need. Only a few species mentioned in the volume are not illustrated—typically because megascopic specimens are not known. Wherever possible, Lauf chose to select photographs to illustrate good specimens that an interested collector could actually hope to obtain and study. There are many photographs of examples from classic worldwide localities that have produced abundant good-quality samples, most of which are still available at all price points.

Each section of the book contains a general introduction, then subsections on taxonomy, atomic structure and morphology, chemistry and color, formation and geochemistry, and individual descriptions of relevant mineral species. The narrative portions of each section cover the history of the scientific knowledge about each species and related species within a group in generally accessible language without tabulating all of the properties that a specialist might determine in his/her laboratory to confirm the identity of a specimen. Most collectors depend upon the expertise of the dealer or collector who supplied the specimen and will rely on color, luster, and crystal morphology (described in this volume) to confirm each species identity in their collection. The section on the humite group illustrates the challenges faced by collectors when mineral species recognized by the International Mineralogical Association require chemical analysis and/or X-ray analysis for accurate identification—the tools available to most collectors, hand-sample physical and optical properties, don't suffice. Many collectors will find the inclusion of obsolete names (in italics) and modern scientific names in this book to be helpful when reading older descriptions or examining historic collections or old specimen labels.

The narrative includes regular scatterings of information about the history of important specimen localities, the variety of names associated with some localities (e.g., caption for figure 347: Wilui River region) and the evolution of accepted mineral names (including varietal names, shown in italics for clarity). The discussions of how accepted names changed as improved determinative information became available after specimens were in the marketplace will be of use to all collectors (e.g., introduction to the humite group).

Except for already-trained specialists, the diagrams of the atomic structures are less effective supporting the narrative than the magnificent color photographs of typical specimens. Lauf made a wise choice to include access to the CrystalMaker CrystalViewer software online to all owners of this book. Predefined data sets on the website for minerals covered in this volume allow the user to continuously rotate and view the atomic structures from any direction—a genuine aid for the visualization of the three-dimensional relations upon which many megascopic properties discussed in the narrative are based. For the more scientifically knowledgeable collectors, access to the CrystalMaker CrystalViewer software might be more valuable or equally valued as the specimen photographs.

The ten figures with traditional black-line drawings of well-formed crystals scattered throughout the book would be more effective if the dashed lines were more distinct—in some of the drawings the dashed backside lines are difficult to distinguish from the solid front-side lines (compare figure 405 top right as an effective drawing; figure 154 top and center left drawings as confusing). Some of the color atomic structure drawings could be increased in size 20 percent within the existing figure frames to increase their clarity and effectiveness (e.g., figures 6, 7, and 8).

Although there are a few flaws related to inadequate proofreading (e.g., “atomic structure and morphology” heading is missing in the humite section, on page 36 there is an extraneous “a” after species names in footnote a, and the Mineral Index incorrectly refers to page 81 for vanadomalayaite), none significantly detract from the narrative.

This guide is a useful compendium, comprehensible to a wide audience, and a bargain. Who could ask for more? Congratulations to Lauf.


Care and Documentation of Mineral Collections by Jean F. DeMouthe. Mineralogical Society of America; msa.minsocam.org/orders.html. 94 pages; 2017; $30 (softbound).

 

Care and Documentation of Mineral Collections is a book of the sort that has long been needed to lay to rest many of the practical questions that collectors have from time to time and for some reason are unable to find adequate answers. The author, the late Jean F. DeMouthe of the California Academy of Sciences, was involved with the curation of mineral collections for decades and was eminently qualified to compile under one literary roof the many pieces of information and advice that collectively lay the ground rules for the proper care, display, and documentation of rock and mineral specimens in personal, academic, or museum settings. The value and timeliness of the book are reflected in the fact that it was chosen to be Publication 7 in the Mineralogical Society of America's Monograph Series.

The book consists of ten chapters, four appendices, and an index. Chapter 1, a brief introduction, is followed by a chapter that discusses the various ways a collection can be organized and includes the more obvious, such as alphabetical, chemical, and by locality, but also the less obvious methods that include layered organization, derived species, and ancillary collections. Chapter 3 consists of discussions related to the all-valuable topic of documentation and covers such items as the cataloguing of accessions; the integrity of data; the use of photographs and computers; appraisals; and even bar codes. “Ancillary Collections,” covered in Chapter 4, is followed by an important chapter on “Preventive Conservation” in which ten agents of deterioration, green conservation, and emergency conservation are discussed. Chapter 6 covers all aspects of storage including security and exhibits. Hazards, safety, and risk are the subjects of Chapter 7 and include toxic specimens, personal protection, risk assessment and management, and disasters such as fires, floods, and earthquakes. Administrative policies are the topic of Chapter 8, which includes thirteen criteria for deaccessioning specimens. Chapter 9 is devoted to private collections and briefly covers appraisals, insurance, loans, and collection storage and care. The final chapter is devoted to informational issues and contains the book's bibliography and listings of other resources such as the Internet and organizations. Internet resources is broken down into convenient groups such as government sites, mineralogy, and conservation of collections and library materials. The four appendices include ones devoted to computer database fields; environmental conditions for collection storage; chemicals, adhesives, and consolidants; and toxic minerals.

The book is well illustrated with fifty-three instructive photographs and drawings. There are four tables that include lists of pests and their respective damage; good materials useful for collection curation; materials that should not be used in the curation of mineral collections; and toxic minerals likely to be found in collections. The overall quality of editing, printing, and binding is good. The organization is well thought out, and topics are developed in a straight-forward manner. There are few points of criticism, but I did find that “freezing” is discussed as a chemical to use with care and common sense in Appendix C.

Care and Documentation of Mineral Collections is an easy and interesting read. There are many places where suspicions are confirmed when the author clearly states what we always thought we knew in our own muddled way. In any event, she leaves no doubt in other places exactly how something should or should not be done. I recommend it to all mineral collectors who are serious about the storage, preservation, and documentation of their collections.


Mineral and Gem Deposits of Eastern Brazilian Pegmatites by Jacques Cassedanne in collaboration with Simon Philippo. Natural History Museum of Luxembourg, 25 rue Munster, L-2160 Luxembourg; musee-info@mnhn.lu. 671 pages in 2 vols; 2015; €50 plus postage (softbound).

 

This very ambitious undertaking, the publication of Mineral and Gem Deposits of Eastern Brazilian Pegmatites, is a somewhat challenging but valuable reference for those interested in learning the details of Brazilian pegmatites—their classification, mineralogy, and mining. The first chapters are important in that without them one can quickly become lost in geology, geography, and pegmatite theory, particularly as presented in this book. The reader must also appreciate the fact that this book was not originally written in English, and the translation is at times literal and clearly by one not overly familiar with English terms as they apply to geology and descriptive mineralogy.

The book begins with a comprehensive table of contents and a preface that describes the relationship between the Natural History Museum of Luxembourg and Brazilian mineralogical research. Chapter 1 is an introduction to Brazil's geology and geography. The geographic sections are particularly important, for they set the stage for the many unique features related to climate, vegetation, and relief, all of which impact gem and mineral production. Chapter 2 is devoted to pegmatites. It contains three sections, including an introduction that begins with a review of magmas and igneous rocks and ends with pegmatite classification, a second section that discusses the eastern pegmatite province, and a third that introduces the fundamental mineralogy of pegmatites. Within this final section are separate discussions of quartz, the feldspars, the micas, cookite, schorl, and some alteration minerals. Chapter 3 is a Pandora's box of interesting information devoted to detrital deposits that contain economic gems derived from the weathering and erosion of pegmatites. Volume one ends with Chapters 4–6, a series of sections that describe pegmatites on the basis of dominant or most important gem and mineral species. There are, therefore, chapters on beryl-rich pegmatites, pegmatite deposits of gem tourmaline, and those of importance because of the presence of other mineral and gem commodities, with separate sections on garnet, rose quartz, scapolite, kunzite, and topaz pegmatites. Each chapter ends with an appendix that tabulates the important features of the deposits of the type under discussion including all location data, geologic parameters, type of workings, mineralogy, host rocks, and production.

Volume 2 contains pages 377–671 and is a continuation of the discussion of pegmatites based on dominant mineral or gem products. Chapter 7 is devoted to pegmatitic rare gem deposits and is divided into ten sections that include such interesting discussions as petalite deposits, phenakite-rich pegmatites, euclase deposits, amblygonite deposits, and even amethyst and citrine occurrences. Chapter 8 is titled “Other Phosphates of the Pegmatites” and includes short discussions of an amazing 90 species. The overall phosphate suite is reminiscent of that encountered in the Keystone and Custer districts of South Dakota's Black Hills and even includes the namesake mineral robertsite. Chapter 9 contains a similar series of descriptions of other accessory minerals found in these pegmatites. The chapter is arranged in a classical chemical format beginning with elements and ending with silicates. There are 114 individual entries including 2 organic compounds. Of the 24 sulfides listed, 11 are copper minerals. Similarly, there are a surprising 18 arsenic minerals identified from these pegmatites. The book closes with an index that is for the most part simply an alphabetical locality listing.

Mineral and Gem Deposits of Eastern Brazilian Pegmatites is a good reference work once the reader becomes familiar with the book's organization and terminology. Relative to the latter, a useful glossary insert containing the English translation of many Portuguese words used in the text accompanied my copy. One of the important strengths of the book is its illustrations. They focus on mineral specimens, but there is also an abundance of maps and mine and locality photographs. For example, Chapter 5, dealing with gem tourmaline-bearing pegmatites, contains 96 illustrations, 47 of which are locality-related photographs. On the other hand, Chapter 9 contains 88 photographs, only 12 of which are of localities; with the exception of a map, the remainder are of specimens.

The book's overall presentation is good with tight binding, sharp, crisp illustrations, and slick paper. A final editing by one familiar with geologic and mineralogic English would have improved the text dramatically. Still, it is a very worthwhile addition to anyone's mineral or gem library.


Agates—The Pat McMahan Collection by Pat McMahan. Self-published; agateswithinclusions.com. 496 pages; 2016; $129.99 (hardbound).

Have you heard about this new agate book? But wait, do you really need another book on agate when your bookshelf already buckles under the weight of over 2,300 pages, including the well-known agate trilogy authored by Johann Zenz and published by Rainer Bode? The answer is simple: Yes, this is an agate book you should have.

You may have heard the name of agate collector Pat McMahan. In Zenz's second volume, Agate II, published in 2009, McMahan contributed 300 (of the 656) pages. The book Agates—The Pat McMahan Collection is self-published by the author with the help of his two sons, one responsible for the photography, the other acting as editorial assistant.

The aforementioned Zenz, an agate collector himself, introduces McMahan. Zenz, who also served as mineralogical consultant for the book, points out (p. 12) that most specimens in McMahan's collection are self-collected in a world where “investors now pay unimaginably high prices for what are called ‘masterpieces’ of the mineral, rock, and gemstone world.”

In two pages of preface and acknowledgments, McMahan reminisces about how he got into collecting, cutting, and polishing agate. He mentions numerous friends and family members who encouraged him in his hobby and supported him in the production of his book.

A 7-page chapter called “Meet the Agate Family” explains and illustrates thirty-one terms that are often used in the agate community. Some were initially a little confusing to me because they have different meanings in the earth sciences versus the agate community. Oolites, for example, or pisolites have entirely different meanings in each world. In the geosciences community, both terms have a genetic basis. In the agate community, however, the former indicates spherical features smaller than 2 millimeters (in McMahan's book it is .25-inch), whereas the latter is used for spherical aggregates larger than 2 mm (.25-inch in McMahan's book). Other terms such as rutilated quartz, on page 20, seem misplaced and are confusing in a book on agate. Maybe that was why this chapter is called “Meet the Family” instead of “Glossary.”

The section with agate localities/deposits starts on page 24, and for almost 300 pages, we wind our way through U.S. localities from nineteen states, arranged in alphabetical order. Some are represented by just a single page (e.g., Alaska, Kansas, Missouri, and Nebraska); others fill fifty or more pages (e.g., Arizona, California, and Oregon). The section “Agates from Around the World” starts on page 313 with exceptional agate specimens from deposits on the African continent: Botswana, Egypt, Madagascar, Morocco, Namibia, Congo, and Tanzania. Specimens from China, India, Indonesia, Kazakhstan, Mongolia, Russia, and Turkey are presented from the Asian/Eurasian continent; agate from the Australian continent are from Australia and New Zealand. After visiting the European countries of Bulgaria, Czech Republic, England, Germany, Hungary, Italy, and Poland, we move on to Central and South America. Agates from the Mexican states of Aguascalientes, Chihuahua, Durango, Sonora, and Zacatecas are shown with, not surprisingly, Chihuahua agate taking up the most pages. The trip around the world continues with Panama and Argentina and ends in Brazil.

An incredible number of agate deposits are covered. On that journey we see some of the best agates, and they all reside in McMahan's collection. They comprise an amazing array of shapes and colors. Some resemble abstract paintings, others are reminiscent of Rorschach tests, still others look like landscapes, faces, plants, and strange objects … there are no limits to what one's imagination can conjure up.

This is a coffee-table book with large-format color photos, colors that are dead on. A close look at the colorful agates McMahan displayed at the 2016 Denver Show showed that the agate colors in the book are as close to the actual specimens as possible. The photographer and prepress did a great job, and the Chinese printer has delivered quality.

In general, photo captions are very concise, in most cases giving just the deposit and size. Some, however, give brief descriptions of individual deposits, mining logs, collecting anecdotes or stories about the colorful people involved in the hobby, and the occasional name-dropping of sources. McMahan wanted to showcase his collection, its wide color spectrum, and the huge variety of internal structures of agate. And he delivered!

Despite the book's title of Agates, a substantial number of pages are dedicated to non-agate specimens: Bisbee, Globe, and Morenci azurite, chatoyant nephrite (aka “Ghost Jade”) from Nevada, Utah variscite, South African sugilite, malachite from the Republic of Congo, ruby in zoisite from Tanzania, Russian charoite, rhodochrosite stalactites from Argentina, and quartz varieties with rutile, epidote, and “sagenite” inclusions from Brazil. Seemingly, if something is colorful and polishes well, it has a place in McMahan's collection. However, it would have been less confusing if the non-agate mineral species had been separated from the agate and its varieties.

A bit upsetting is the missed opportunity to bring more clarity into the nomenclature of agate and agate varieties. I found numerous examples of confusing and ambiguous names for agate varieties, mixed with trade names and agate varieties that have been given the same names as IMA-approved mineral species. I am pretty sure that French mineralogist Emile Bertrand (1844–1909) would turn in his grave if he knew that “bertrandite” aka “Tiffany Stone,” from Spor Mountain, Utah, bears the same name as the mineral named in his honor.

Also disappointing is the bibliography. It is available only online—yes, it is a clever way to steer traffic to the website—but no link on the website reveals its existence. A total of thirteen references, ten of which have been published since 2000, seems meager compared to the wealth of visual information conveyed by the book.

Nevertheless, should you think this agate book is just another publication on the non-crystalline variety of quartz, think again. It is a worldwide locality guide with excellent pictures of the best agates. However, you have to get over the inconsistencies in the glossary, some irritating misspellings, and the inconsistent use of upper- and lowercase, all of which would have benefited from a more thorough editing. No one summarizes this book better than agate collector extraordinaire Brad Cross, who makes the following recommendation (http://agateswithinclusions.com/book): “If you have any interest in agates at all, I urge you to obtain a copy of this fine book.” I agree; what could be a better endorsement?


Diamond: The Ultimate Gemstone, eds. Jeff W. Harris and Gloria A. Staebler. Lithographie, Ltd., POB 234, Arvada, CO 80001; www.lithographie.org. 152 pages; 2017; $40 (softbound).

 

This is Mineral Monograph No. 19 in the series published by Lithographie, and it bears the hallmarks of quality in design and layout shown in the others. Publisher Gloria A. Staebler does have an eye for an attractive product, although her choice of A4 size (210 × 298 mm) is a little unusual for the North American market, and her placing of pages is a trifle idiosyncratic. I suppose that placing a separate, uncolored page on the Hope Diamond in the middle of an introductory piece on the history of diamonds is stylistically and editorially acceptable (the stories are related), but it does cause some momentary continuation confusion for simple linear readers such as I.

The text comprises fifteen short monographs authored by twenty contributors with impeccable credentials in the field. Six co-contributors aid the authors, and a host of illustrators past and present enlighten the pages. Among others, illustrators such as Victor Goldschmidt, Harold and Erica Van Pelt, John Koivula, Jeff Scovil, and Michael Bainbridge will be familiar to most readers. A valuable addition is a seven-page section, “Literature and Cited Works,” cleverly interlaced with full-page advertising from well-known mineral dealers.

In assembling such a constellation of contributors, however, the editors have managed to create a compendium of information that ranges from historic to deeply scientific, while at the same time comprehensible to the intelligent reader. Those who are impatient with the minutiae of the history of diamonds at the beginning will probably salivate at the introduction of phase diagrams later, and those who hoped to have left Gibbs free energy back in classrooms years ago might well react in opposite fashion. The point is that just about everything one needs to know about diamonds is included. From the initial history section, through the geology of diamonds, the mineralogy of diamonds, and on into crystallography, defects, gemology, sources, synthesis, and even theft of diamonds, the presentation is crisp, sharp, and authoritative. For example, if author Dr. John Jaszczak says (p. 26), “In diamond, the 2s electron orbital and three 2p orbitals of each atom hybridize into four equivalent sp3 orbital …”, I'm inclined to believe him. That's a little tongue-in-cheek, but it does illustrate that the book is not an “Oh, that's so pretty” volume. It is a pretty volume, but it has substance. Of course, Jaszczak also notes that, in 1965, General Electric made diamonds out of peanut butter—giving us more food for thought.

In his monograph on “Geology of Diamond,” Dr. Bram Janse provides an excellent illustration of the development of kimberlite pipes and dikes, but he also gives a telling description of Clifford's rule, which states that while kimberlites are found in many places, diamond-bearing kimberlites are to be found only on older cratons. The rule was formulated in 1966, but it hasn't reached many collectors. (If I had known the rule in 1995, I might not have spent so much time poking in an exposed kimberlite on the east coast of New Zealand.) A little later in the book, a monograph by Nick Norman titled “Diamonds in Africa: A Tribute to Tom Clifford,” expands on Clifford's rule and goes on to describe diamond sources in Africa generally. It also leads into the next four monographs describing diamond localities in Arkansas, Russia, Australia, and Colorado. One locality, a little different from the others, is outer space. A short piece by Dr. Emma Bullock describes meteoritic diamonds, some of which may pre-date our solar system. Others, such as those found in the Ries impact crater in Germany, were formed when the meteorite struck. The Ries impact created an estimated 72,000 tonnes of miniscule (less than 0.2-mm) diamonds from local graphite sources.

Two monographs caught my attention for different reasons. The first, “Diamond: Intimate Portraits” by John Koivula and Elise Skalwold, is memorable for Koivula's stunning photomicrographs of the inclusions and growth structures in diamonds. Readers will be familiar with garnet inclusions in diamond, but bright blue sapphire and blades of kyanite raise questions about the milieu in which these diamonds developed. Similarly, a spectacular shot of the sparkling ghost-edges of an otherwise invisible phantom is a mind-boggling example of Koivula's skill.

The second, “Laboratory-Grown Diamonds” by Drs. James Butler and Boris Fiegelson, is in many ways more down-to-earth, but in others equally stratospheric, explaining as it does the genesis of high pressure and high temperature (HPHT) and chemical vapor deposition (CVD) diamonds. That's where phase diagrams and free energy come in, though at my age I refuse to bow to the East at the mention of J. Willard Gibbs (it's obligatory for thermodynamicists). The intellectual atmosphere of this monograph may be rarified, but the practical illustrations of the processes involved are fascinating and well worth reading.

This has not been an exhaustive catalogue of the contents of the book; there are other equally interesting monographs involved. I have simply covered those that caught my attention the most. In general, the few flaws I mention are insignificant, and the illustrations throughout are well chosen and well reproduced. I would, however, have liked to see a true index. The table of contents is useful for finding things, but only if one can remember in which monograph the item occurred. In spite of that, it's a well-crafted piece of work and, at $40, worth the price.

 

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