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.


Welcome to Hexagonal Dipyramidal: A Blog about Minerals, Mineralogy, and more

More than once, I’ve looked for signs of people writing about minerals, collecting, and mineralogy. There are a few out there on the web, but not as many as I might have expected. Although there are geologists represented in many fora – as well there should be – there are not that many people talking about the mineral sciences.

People continue to be fascinated by rocks and minerals, from small children to adults. Sometimes, they’re interested for the right reasons, sometimes not. I’ll clarify what I mean by that shortly. But it is apparent that local gem and mineral shows still draws thousands of people out on their week-ends to come and look at the wares on offer, be they jewels, minerals, or fossils, that there is an appetite for this sort of knowledge, this sort of fun.

And it is fun. When I was at school, I was the only kid I knew who collected rocks and minerals. For that matter, I was the only kid that I knew who was spending his lawn mowing money on back numbers of the Mineralogical Record, rather than on proto-attempts at wooing. As Stephen Fry once said, “this was in the seventies, and girls hadn’t been invented yet.” I vividly remember a cartoon drawn by a school friend at the time – a crude image of someone (presumably me) wearing a knapsack and carrying a gun, with the legend “have fun rock hunting”. So the amusing misconceptions were perpetuated, but I was still having a good time. Minerals, with their mysterious chemistry and sometimes sublime appearance under magnification, could be a topic of endless interest… For me, the always were.

So I’ve been giving this idea some thought, and the notion hasn’t gone away. I’ve also been looking at my collection again, for the first time in years, and realising that (a) I have some surprisingly good things, (b) that there are some stories to be told around that collection, and (c), that my interest has revived in a surprisingly pronounced manner. For those reasons, at least, I should, I think, maintain a blog about mineralogy. And other things, of course, but mainly mineralogy. And we’ll see how that goes.

I’ve maintained a blog before, so this isn’t new territory, but it is something slightly different, in that I will attempt to stay – for the most part – on one topic. And I’ll also be shooting for regular entries – but we’ll see how well that works out too…

Onward, then, valiant reader!