Letter to the Editor

My original intention with this post was to just post a quick, informational link to the current issue of Rock & Gem magazine. Then, however, I was distracted. So distracted, in fact, that a letter seemed warranted. It will explain everything:


To the Editors,

I have subscribed to Rock & Gem for roughly two years now. As a science writer, avid mineral collector, and sometimes geology educator, I have found your magazine’s more conversational tone and more generalist stance to strike a good balance between publications obviously inclined toward professionals in the geosciences and the community of interested amateurs.


One of the features which I have generally been pleased with has been the ‘Rock & Gem Kids’ section, which I have shared with my own children. Obviously, interesting and educating the potential next generation of amateur lapidaries, mineralogists, and geologists is an important task. Kids are naturally interested in these things, as I always find when I give talks to school-aged children (which, in fact, I did just yesterday). They are often hungry for knowledge that they simply don’t get in school.


That is why I was frankly appalled to read the current ‘Rock & Gem Kids’ section discussing ‘Kansas Pop Rocks’ (February, 2011). No, it was not author Greg Sweatt’s line about throwing them into the fire until they exploded, although that was certainly questionable. Nor was it even the remark about how the pyrites are believes to have formed around fossil shell, bone, or tooth (I could find no citations for this, but it would be conceivable in some cases). Rather, what I am referring to is this:

“Rare, perfect pop rocks sell for big dollars as metaphysical stones, as they do emmanate energy, and people sensitive to that energy value them as healing stones.”


Who, precisely, proof-read this article? If you hold to any pretense of being even a remotely scientific publication, they merit a stern talking-to, if not outright sacking. And your author, Mr Sweatt, should be cautioned against putting nonsense like this in his articles.


Claims of “energy emmanation” are often made by those with more metaphysics than science in mind, without any clear understanding of what that “energy” might be, or how it is “emmanated”. Funnily enough, when materials which do “emmanate energy”, such as uranium and thorium-based minerals, or fluorescent minerals exposed to UV radiation, are discussed, these same people are often strangely silent.


Pyrite Concretion, Niobrara Chalk Member, Western Kansas

A pyrite concretion. Watch it closely. Did it move? Wait – did it wink at me just then? No, it didn’t. Photo Credit: Personal Collection.

Let’s be clear: these pyrites don’t emit energy. Not at all. Not one iota. I have one sitting on my desk right now. It is roughly ovoid, about three centimetres in diametre, and a sort of dark bronze colour. It doesn’t glow in the dark. It doesn’t trigger a Geiger counter. It refuses stubbornly to fluoresce. It is not magnetic. It is neither unexpectedly warm nor unexpectedly cold to the touch. It interferes with neither my computer, my mobile, nor my landline telephone. In short, it emmanates no energy whatsoever in any expected sense. If you want to claim that there is an “energy emmanation” from one of these stones, then you’d better be prepared with your data. Show me your experimental method. Demonstrate your hypothesis, quantify and qualify the “energy” being emitted. Why? Because that is how science works.


Why does this bother me? Simply this: because as a publication dealing with rocks, minerals, and gemstones, Rock & Gem sets itself up as a trusted source for science information. And in that single statement cited above, your editorial stance has been shown not to be scientific. That makes it very difficult for me to be confident in your publication as a trusted source. Remarks like the one above about “energies”, even if they are just meant as “a bit of fun”, have no place in discussions of the real world.


I would point readers interested in further clarification to the recently revised Second Edition of Rex Buchanan’s Kansas Geology (University of Kansas Press, 2010) and to D.E. Hattins 1982 paper ‘Stratigraphy and depositional environment of the Smoky Hill Chalk Member, Niobrara Chalk (Upper Cretaceous) of the type area, western Kansas”, Kansas Geological Survey Bulletin 225 (which sadly doesn’t appear to be available online at this time). Kansas County Bulletins published by the KGS can be found here, and Gove County, as well as other counties where the Niobrara chalk is in evidence, is represented in past publications which are free for all to read.


Sincerely yours,
Hexagonal Dipyramidal
So that’s how I spent my morning. Nothing like a letter to the editor to make one hungry for a bit of breakfast and the wine of the vanquished.

Minerals in the News: Calcite… and Invisibility!

The other night, I was scrolling through my feed reader (and honestly, I was trying to go to sleep) when I saw this story: Using Special Crystals, Researchers Make a Paper Clip Invisible. After reading a headline like that, it’s a little harder to go to sleep, especially when you find that your life-long dreams of rendering paper clips invisible are within a whisker of becoming reality.

The suggestion that these were “special crystals” in the article’s headline was somewhat surprising, given that they were described as calcite, which is one of the most common minerals in the world.  This consternation is borne out by the article’s content, which states that to render an object invisible:

“In both experiments, researchers had to finely tune their crystals—they’re technically composite crystals, as the researchers basically glue together two crystals with opposite crystal orientations—then placed them over small but entirely visible objects (MIT used a small metal wedge the size of a peppercorn; Birmingham went bigger, concealing a paperclip). “

In other words, naturally occurring calcite crystals were modified and used to precisely refract visible light. Clearly, this is more difficult than simply putting one Iceland spar on top of another and seeing something disappear (try it for yourself the next time that you have a couple readily to hand – there are obviously other mitigating factors). But it is a remarkable discovery.

Calcite Under a Green Laser

An Iceland Spar calcite crystal is subjected to the light from a green astronomical laser. Note the beam path in the crystal. Photo Credit: Personal Collection.

The optical properties of some crystals of calcite, specifically, the iceland spar rhombohedral crystal, are well-documented and thoroughly understood. When calcite crystallises in this particular form (one expression of the trigonal hexagonal scalenohedral (32/m) form), the planes within the crystal cause light to be refracted. Depending on the power of the light source, a projected beam of light fired through calcite, like that of a green astronomical laser, can result in the beam being spread out at regular intervals having been refracted along the crystal’s internal planes. When the crystal breaks light travelling through its structure, this is known as double-refraction, or birefringence.

The property is also well demonstrated by simply placing the crystal over some text, and noting the optical effect:

Text from a label doubly-refracted by an Iceland Spar calcite crystal. Photo Credit: Personal Collection.

A fossil impression of a trilobite head and upper thorax, Cambrian Era, House Range, Utah. Photo Credit: Personal Collection.

Calcite is also known to have acted as a component in the eyes of trilobites, a now-extinct arthropod species which dominated the planet for approximately two hundred and fifty million years, from the Cambrian through the end of the Permian. These complex lenses are one of many interesting features of this fascinating and long-lived group of creatures. Interestingly, the use of calcite in optical structures persists into the modern day, in the brittle star species Ophiocoma wendtii.


The rhombohedron is one particular expression of the crystal form of calcite.  Others are representative of varying conditions of temperature and pressure under which the crystals have formed.  For example, a specimen like this one from Dal’Negorsk, in Russia, is not only differently crystallised, but faintly fluorescent:

Calcite crystal cluster, 7 x 4.5cm, Dal'Negorsk, Russia. Photo Credit: Personal Collection

Calcite crystals on matrix, Somerset, England, 7 x 3.5 cm. From the same cave system which produced the "Flos Ferri" calcites (qv). Photo Credit: Personal Collection.

And, interestingly, this English calcite from the same cave system in Somerset which produced Flos Ferri aragonites exhibits an unusual expression of the 32/m form. In this case, though, the calcite is not fluorescent, for reasons which I will try to describe at length in a future posting. Interestingly, English fluorites from more northerly counties, including Durham and Cumbria, are famous for their fluorescence, the regional geology being significantly different. Again, fluorite will be the topic of another, future posting.

Calcite crystals overgrowing earlier (orange-brown) dogtooth calcite crystals. Overall size 6.5 x 5cm, Reynolds County, Missouri. Photo Credit: Personal Collection.

As I mentioned, calcite is one of the most common minerals in the world, and it occurs in a number of very interesting forms. In northern missouri, it is also one of the few minerals to be found in the local sedimentary rock.  In fact, it is common throughout the state, being found in quantity in the lead and zinc deposits of the Tri-State Area, in the Pennsylvanian-era limestones of the north, and in the east, in Reynolds County and elsewhere. To find that such a material now has an added utility and scientific value is interesting and gratifying, in the least.

Minerals in the News: Molybdenite

The lovely flat metallic hexagonal crystal habit of molybdenite, in this attractive specimen from the Moly Hill Mine.

Molybdenite is a molybdenum sulfide mineral found around the world. One of the best locations in North America is the Moly Hill Mine in Canada, which is a source of beautiful It has now appeared in the news as a new breakthrough material with potential applications in semi-conductors and nanotechnology.

It appears that, due to its nearly two-dimensional crystal structure ( see above ), molybdenite may be even better in ultra-thin applications than silicon, which forms three-dimensional crystal lattices. Additionally, this new structure will use a hafnium oxide layer, which is simply a bonus step in mineral-nerd cool, as halfnium only occurs in a handful of comparatively rare minerals (to be exact, I count all of three on Mindat, of which one, hafnon, is the halfnium analogue of zircon and thorite, and is definitely on my short list of “species to collect, urgent”… but I digress).

Diagram depicting the integration of molybdenite into a transistor. Image Credit: EPFL

For more, this article from Science Daily (“New Transistors: An alternative to silicon and better than graphene) provides an excellent overview. And while I’m not sure that I care for the title of this article ( because guess what? I had heard of molybdenite already ) but here’s the article from the Discover Magazine blog. Have a look!

Mineralogy in the Science Museum?

I found that I hadn’t even opened my latest issue of The Mineralogical Record when the new one turned up in my mailbox this afternoon. As may be evident from the infrequency of blogging here, it’s been that sort of season. I wanted to take a moment, though, to review a couple of – admittedly quite minor – points which occurred to me in light of the most recent issue.

The Mineralogical Record, November/December 2011The first thing that struck me was how nicely this issue fell in with a number of my own recent activities. The cover features a red beryl from the Wah Wah Mountains, Beaver County, Utah. While I didn’t quite make it that far in my own travels last July hunting trilobites west of Delta, UT, I did get to the Topaz Mountain Rockhounding Site, in Juab County, which was beautiful, rugged, and, unfortunately, entirely beyond the hand tools that I had brought with me. Having already dragged my family that far out into the desert (and to nine year olds, an hour’s drive seemingly into nowhere is a long way, I have it on good authority), I elected to turn back, and made certain to get a pretty topaz and a nice little red beryl from the rockshop in Delta instead. Not as satisfying, but sufficient, especially considering the number of trilobites which we had come away with. Aside from which, it was either that or miss Moab and Arches National Park on the way back toward Colorado, and I had really set my hopes on that (by the way, I can’t recommend Arches National Park enough: it is amazing and awe-inspiring, whether you have geological inclinations or just like gorgeous, unexpected scenery which seems almost otherworldly).

Specimens from the California Academy of Sciences

Specimens of Kunzite and Rose Quartz from the California Academy of Sciences, April, 2010

Then, immediately inside, in the Notes from the Editors column, was a piece about the newly refitted California Academy of Sciences, in San Francisco, which I had visited in April. The letter was not exactly a favourable one, lamenting a note published in the San Francisco Chronicle on 3 September 2010, regarding the recent remodelling of the Academy. The updating of the facility saw the removal of its “fabled gem and mineral hall” (I’ve searched, but I haven’t yet located any images of the former mineral hall; if you have one, feel free to drop me a line), which has – and here I entirely agree with the author’s point – wrong-footed a lot of collectors who have donated what are, judging from what I saw, some remarkable mineral specimens. The article further claims, inaccurately, that the mineral collection is secreted “in the basement” (it is actually positioned on the second level, among what appeared to be administrative offices, next to a very impressive set of megalodon jaws). Unfortunately, this particular room on the second level is only accessible to guests of the Academy who spring for the – pretty expensive – VIP Tour. Essentially, the point of contention is between the mineralogy community, and donors like San Franciscan Jack Halpern, against the Academy, is that all of these donated specimens should be out for public viewing, a point with which I would agree.

During my visit last April, my wife and I were fortunate enough to go on the VIP tour, which included the mineral room on the second level. I’m assuming that this is only a small part of the Academy’s collection, but, for what was there, it was impressive. As this was my first visit, I had nothing against which to compare the relative success or failure except for other science museums that I’ve visited in Kansas, Missouri, Colorado, and Minnesota.

There was a very important point made in the article cited, which was that the California Academy of Sciences is focused, among other things, on evolution education. “Our message is the evolution and sustainability of life on Earth,” according to Academy spokeswoman Stephanie Stone, who went on to say that there simply wasn’t room for everything.

What the Academy does, they do very well. The Morrison Planetarium is phenomenal, even though during our visit some of the experimental presentations did not perform entirely as expected. The exhibits of ocean life were incredible, and my wife, who has some experience with marine life, was very impressed. The evolution and sustainability components are also competently and well-represented, and knowing the poor state of evolution education as I do, I must applaud the Academy’s efforts to counter the lunacy of endeavours like the Creation Museum in Kentucky.

Benitoite in the California Academy of Sciences, April, 2010

Benitoite in the California Academy of Sciences, April, 2010

Does that mean that I don’t want to see more mineralogy represented, for public viewing? Absolutely not. I would hope that the academy can utilise the vast space available to them to find a home for at least some of their collection. Mineralogy should fit into the sustainability message quite well: there are questions of the availability of mineral resources, the environmental impact of their extraction, and their use and re-use as we move further into the 21st century – it will only take a creative mind to work out the best way to make the link.

New Issue of the Mineralogical Record hits the stands!

It’s that time again, when the smell of fresh UV coating emerges from the polythene shipping bag, heralding the arrival of the new issue of the Mineralogical Record. It’s a special time, a six times a year pleasure in the mineral enthusiast’s calendar.

This issue features an article by Editor in Chief Wendel Wilson on the beautiful blue-grey Celestines of Mahajanga Province, Madagascar, collector’s reminiscences of Minas Gerais, Brazil, and a remembrance of the Munich gem and mineral show by the founding editor of the Record, John S. White. As always, an issue to savour, then add to your permanent collection…

Frontiers in Mineral Identification: Rendering Your Laboratory Obsolete?

One of my diversions in the past few years has been teaching myself how to do chemical analysis of mineral specimens in my collection. With the correct reagents, some glassware, acids, and a decent burner, it’s possible to tease out a lot of the fundamentals of a mineral’s chemistry just by performing various procedures and observing the results. Books like Orsino Smith’s Chemical Analysis and Determination of Minerals give a sense of the state of the art dating to the 19th century. When you move beyond the basic physical properties of minerals, this can be an enormous aid in identification (about which topic I’ll write more in a later entry).

In the 21st Century, of course, these methods of chemical analysis seem somewhat quaint, somewhat dated. And with the advent of X-ray fluorescence analyzers, these techniques may well seem positively mediaeval. Or will they?

An XRF scanner in use, from the Thermo Scientific website.

As discussed in the most recent issue of Rock & Gem magazine (September, 2010) by noted author Stephen Voynick, the advantages of the new generation of hand-held X-ray fluorescence (XRF) scanners are speed, portability, and ease of use. XRF devices take advantage of the fact that when an X-ray strikes an atom, electrons are dislodged, and in order to regain electrical stability, the electrons are replaced by other electrons which release fluorescent X-rays, the energies and frequencies of which are unique to each element. With the appropriate detector, these energies and their frequencies can be measured – that’s where the XRF scanner comes in (please read Voynick’s article for a more detailed description – link to follow when it’s available online).

Of course, there’s a price for such technological advancement – in this case, an individual unit from Thermo Scientific‘s Niton Analyzers range, sells for about $42,000. Which means that, while undoubtedly useful, my home laboratory is still substantially cheaper. And the units do have their limitations – the model tested by Voynick, calibrated for geochemical analysis, could identify only 29 elements, and nothing lighter than chlorine (atomic number 17). Not that having an instant analysis of the percentage of heavier metals in a sample is anything to sniff at. But obviously, it would be hoped that as the price drops, the number of elements readily identifiable will increase.

It’s not really a choice, of course – not for me. I’ll continue to work on identification in the traditional way: hardness tests, specific gravity, streak, chemistry… but eventually, who knows? XRF scanners could eventually become an invaluable part of hobbyist mineralogy. In the meantime, there’s still the pleasure of spending time looking at something interesting and trying to figure out just what it is… After all, that’s why most of us started out in this hobby.