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Interview with Anton Chakhmouradian

Posted by admin at 10:23 AM on May 7, 2010

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Dr. Anton Chakhmouradian teaches alkaline and carbonatitic systems at the University of Manitoba. I believe that his research is both top-notch and absolutely critical for the furthering of our understanding of rare earths in various geologic settings. This interview was conducted by submitting questions to Dr. Chakhmouradian which he answered and returned on 3 May 2010.

Where did you receive your education?

My alma mater is St. Petersburg State University, the second largest school in Russia. For my master’s and doctoral degrees, I studied in the Department of Mineralogy. The Russian postsecondary education used to be very different from the North American. For one thing, so many young people of my generation were interested in geology that each specialized department within the Faculty of Geology (Mineralogy, Paleontology, etc.) was graduating several students every year. With the collapse of the Soviet Union, that interest has dwindled due to the shrinking job market for geologists, and many of my former classmates have ultimately chosen alternative careers, but others have stuck with geology and don’t regret it.

When and how did you get interested in the rare earths?

I was fortunate that way because several of my former profs were involved in the study of the famous Kola alkaline province from the 1950s through the 80s, so I, too, “got hooked”. Both of my thesis advisors were great mentors who passed their knowledge and passion for geology and alkaline rocks on to me. For my thesis, they encouraged me to re-examine the perovskite mineral group, which included loparite, the principal source of rare-earth metals for the Russian industry to this day. Basically, I have been working on rare-earth minerals since 1992 when I first visited Kola and the Lovozero Mountains, where loparite has been mined for the past 60 years.

Was there a particular person or project that was pivotal in your studies?

There was no single person that I can definitively credit (or blame) for my choice of a career path. In addition to my advisors, whom I already mentioned, I should definitely acknowledge my other mentors and senior colleagues who nurtured that interest and contributed to my development as a scientist, including Roger Mitchell, Anatoly Zaitsev and Rudy Wenk. And, as far as the pivotal project goes, it definitely was my PhD dissertation on the Kola perovskites. These minerals are an important repository for REEs, but, besides that, they commonly occur in rocks hosting all sorts of REE mineralization, like carbonatites and nepheline syenites. Some contain apatite loaded with light REEs, others garnet with Y and heavy REEs, others something else yet, like REE carbonates, monazite, or loparite. Every project I have been involved in taught me something new about REEs, helping me fine-tune my methodology and find new exciting avenues of research.

How important is the study of rare earths?

To just say that it is important would be somewhat of an understatement. In a lot of ways, REEs are to us now like aluminum was to people of the late 1800s. Few scientists realized the real value of aluminum at the time, but can you imagine the aerospace, automobile and even the packaging industries of today without this metal?

What is your specialty within the study of REEs?

I am a mineralogist/geochemist by training, so my professional interests revolve around the various types of REE mineralization that we find in rocks of alkaline affinity. Although many great minds have worked in this field, many key issues of REE geochemistry and mineralization remain unresolved. Why, for example, some carbonatites are loaded with bastnäsite, whereas others contain REEs barely above the background levels? Why is heavy REE mineralization prevalent in alkali granites, but so rare in carbonatites?

I bet, every company and exploration geologist would like to find the practically implementable answers to these questions, but it is generally academics, who have the time and instrumental capabilities to dedicate themselves to such long-run goals. REEs are not the only type of resource that interests me. I also work on niobium, tantalum, titanium, zirconium and uranium-thorium minerals. Anyone interested can look at my research “portfolio” on my website:

http://umanitoba.ca/geoscience/faculty/arc/

Where have you explored for REEs?

Because I am not an exploration geologist, I have never really explored for REEs, in the conventional sense of that word, anyway. Exploration requires weeks and months of reconnaissance and fieldwork, which would leave me essentially no time for teaching, student supervision, public outreach and many other activities that are part of my current job. I like my job too much to trade it for full-time REE exploration. I have, however, consulted for a number of companies.

Whenever possible, I try to get out there and see the rocks, touch, scratch and sample them myself rather than using someone else’s material. To me, nothing is like this first-hand visual experience.

What are some of the most interesting sites that you have studied?

I have seen and worked on many carbonatite and alkaline localities in the Northern Hemisphere and they are all interesting and special in their own individual ways. I find it difficult to rank them in any way, because each of the sites I have visited had something special about it, and it may not necessarily have been anything to do with its economic potential.

To this day, for example, I am very partial to the Murun alkaline complex in eastern Siberia, even though it would be a boring place to explore for REEs. There are some beautiful carbonatites and really exotic silicate rocks at Murun, but they are generally poor in REEs. My wife Katya, who is also a mineralogist and carbonatite expert, found a few specs of burbankite in these carbonatites, but that was it. Nonetheless, I hold this place very dear to my heart because of its rugged beauty, its unique gemstones, and other things that I connect to at some conscious or subconscious level.

Geologically, the most complex and, therefore, interesting of all the places I have been to are probably the alkaline and carbonatite complexes of Kola Peninsula. Places like the giant Khibiny and Lovozero intrusions in central Kola have been explored and studied by hundreds of people, but there is probably still enough work for many more generations of scientists to come.

The most geologically challenging, least explored and, hence, most fun to work on are the recently discovered carbonatites in central Manitoba.

How do you decide how to collect samples?

Optimally, I would like to have some understanding of the place where I would be sampling and its rocks beforehand. If any material collected by my predecessors is available for study, that is ideal. I would look at some rocks and thin sections and try to relate what I see under the microscope to what I read about the place and its geology in the literature.

Coming to the field equipped not only with the right tools but also with knowledge gives you a great edge and allows you to conduct sampling in a systematic fashion. When you are in a completely unfamiliar place, choosing the right sampling strategy can be a difficult task. I’d say there is no unified approach to sampling. It all depends on what you are actually sampling (bedrock, loose material of unknown provenance, drill core, etc.), as well as on your maneuverability and scope of your fieldwork. Is your goal to sample methodically one large outcrop, or you will be moving from site to site? Is there any evidence of intense weathering, metasomatism or metamorphic overprint in the rocks you are sampling? What types of analysis do you have in mind for this material?… You have to have clear answers to all these and many other questions before you can work out the right sampling strategy – right for this particular place and the very specific goals you are trying to achieve.

The only generalization I can make is that your samples have to represent the geology of the sampling site as accurately as possible. Also, I teach my students that, if you want to do a thorough job as a researcher or consultant, maintain a meticulous written and photographic record of what you are sampling. I spend as much time as I can at an outcrop, looking at the same rocks, contacts and structures from different vantage points, jotting down my notes, snapping lots of pictures and trying to come up with some plausible story for how this all formed while, hopefully, enjoying a cup of tea fresh off the campfire.

What kind of scientific equipment do you use to research REE samples?

In my research, I use a wide range of analytical techniques, from the “old-fashioned” immersion oils and X-ray powder diffraction to things like Raman micro-spectroscopy, which allows you to rapidly identify minerals based on how they interact with laser light – whatever gets the job done.

Step one is always petrographic analysis using polarizing microscopy, but it is never enough just by itself because it does not let you distinguish between optically similar minerals and does little for grains smaller than 50 microns.

I teach my students to follow up the petrography with energy-dispersive analysis, back-scattered-electron imaging and Raman micro-spectroscopy to make sure they’d be able to point at any grain in their rock and say what that is.

Depending on the task at hand, available budget and degree of my interest, I can then decide if any advanced, and generally more expensive, work needs to be done. For example, I often use stable-isotope analysis because it helps distinguish carbonatites from other rock types; to figure out the distribution of REEs in my samples, I use laser-ablation mass-spectrometry, and so forth… There is an instrument to tackle almost any problem one can think of. And, like I said, the problem does not have to be of practical nature – I am a scientist, after all, and sometimes “get carried away” in what I do.

If my work on a project turns up something of purely academic interest, I sometimes decide to pursue the new research lead at my own expense. For example, I once did some work for Avalon and stumbled across an unusual mineral which was of no economic value to anyone, but had a very unusual chemistry. So, I asked Don Bubar for his permission to use their material for study, and it turned out to be a new mineral that my colleague Luca Medici and I described in the European Journal of Mineralogy a few years ago.

What advantage does the equipment give you?

It is as essential as an acoustic aid to a hearing-impaired person, only in so many more ways and at many different levels. It gives you the advantage of knowing – not guessing – but knowing exactly what type of rocks and minerals you are dealing with, what their composition is, and everything else you will ever need to know.

The basic equipment, like a petrographic microscope, is well worth an investment, while other, more expensive instruments like an electron microprobe may not be affordable, but should still be at an arm’s length when you need them.

Just one example: Eu is about one hundred times more expensive than Ce. Variations in Eu content in ore minerals such as monazite can be as much as one order of magnitude, which means a tonne of ore can be worth hundreds of dollars or thousands at the same TREO grade. You won’t be able to say if it is hundreds or thousands unless you “go analytical”.

Anyone working on such complex types of mineral resources as rare earths should develop a network of willing and expert collaborators in academia to have access to the equipment and analytical expertise.

How complex is the study of REEs compared to base metals or precious metals?

I think, in mineral exploration, every sector targeting a specific type of resource has its own complexities and challenges. The greatest one for people involved REE exploration, be it companies or academics, is the lack of public awareness, at least at the same level that gold, diamond or base-metal exploration sectors are accustomed to.

One can easily strike a bilateral conversation about gold or platinum with a person off the street, but mentioning neodymium or bastnäsite in that conversation will probably draw a blank stare. This, for the lack of a better word, public ignorance ultimately translates into less support for what I do relative to someone working on platinum, for example, even though the economic impact of these different resource types is probably comparable. Besides, there are purely subjective factors at work here, like the historical role of gold as an inflation hedge, which further amplify the differences between exploration for precious metals and rare earths.

On the technical side of things, the stats are fairly self-explanatory. There are over 250 rare-earth minerals out there, but only about 30 minerals that contain essential Au or Pt. (This is not counting the minerals that contain REE or precious metals substituting for other elements.) So, the mineralogical and chemical diversity alone makes REE research a highly specialized area. On the other hand, REE are much more abundant than any of the precious metals, which means they are easier to detect and track down to the source when it comes to geochemical survey, for example. But, by and large, like I said, every mineral exploration sector has its share of problems.

What are some of the misconceptions about exploration for REEs?

There are many misconceptions, most of which stem from ignorance, the point I have made before. Where should I start? Well, just the lack of understanding of what REE are and what they represent geologically is the source of much confusion and misinformation.

High-profile scandals and spectacular failures in some other areas of mineral exploration, that have enjoyed greater visibility and have been publicized to a much greater extent – like the diamond sector, have cultivated a refined and well-informed generation of entrepreneurs and investors. No one in the right mind would support a diamond project targeting basalts or granites. Unfortunately, the REE sector has a long way to go before it reaches the same level of finesse. For example, just recently, I came across a release claiming that assays from some property returned high values of gold, silver, platinum and other rare earths – and that is coming from a company that is supposed to be advising people on their resource investments.

One of the most common misconceptions is that high TREO numbers equal good ore potential. The problem is that many rock-forming and accessory minerals are capable of incorporating REE, sometimes in significant amounts. Suppose you leave your kids $100,000 in the will – a very round number, right? But what if you have ten kids… or twelve? I have seen a number of carbonatites with overall high TREO values, in which REE are dispersed through a dozen different minerals rather than being concentrated in a single “ore” mineral, and none of those dozen would be abundant enough to get anyone’s adrenaline going. This is what many people do not realize: carbonatites and most alkaline rocks are such unusual beasts that enrichment in REE is actually normal for these rocks.

In some geological settings, more than 50% carbonatites contain >3,000 ppm REE. The catch is to find one with a single REE mineral, which would contain REE at economically viable levels. Secondly, that mineral has to be amenable to processing. For example, over 60% of all proven REE reserves in Russia are “locked” in apatite in the huge alkaline intrusions at Kola, which contains up to 80,000 ppm TREO. However, none of those REE are extracted, even from the Khibiny apatite that is mined and processed for phosphate.

Beyond Kola, there are large deposits of REE-bearing apatite in eastern Siberia, southern Mongolia, South Africa and other places, but technologists are yet to prove that nitric acid leaching of phosphate ore is competitive relative to bastnäsite mining. Then there is eudialyte and several other minerals that may potentially serve as a source of REE, but their economic future is yet uncertain.

What possibilities do you see unfolding in rare earth geological research over the next decade?

First of all, I see some major breakthroughs in our understanding of how and where REE concentrate. With the equipment we have at our disposal these days, we can identify any of the common REE minerals in ten seconds by zapping it with a laser beam, and detect any of the REEs in any sample at the sub-ppm level with a micron-scale resolution. Apart from their obvious practical importance (for resource evaluation, metallurgical studies, etc.), these developments enable us to correlate specific types of REE mineralization with specific rock types, geological processes and tectonic settings more accurately than ever before.

Hopefully, we are going to reach the point soon where our cumulative knowledge could be put together into an integrated model for REE deposits based not only on the type of host rock (which is essentially the extent of our current understanding), but also such parameters as mantle dynamics, tectonic regime, paleogeographic factors, etc. For some deposit types, we are only beginning to unravel the complexities of their origin. Secondly, the recent revival of industrial interest in rare earths has given a boost to field-based research in most parts of the world, which has led to, and will undoubtedly lead to more, exciting finds and, perhaps, even discovery of new deposit types. In Manitoba alone, we have described four new carbonatites in the past decade, three of which host REE mineralization.

Where in the world would you look for rare earths?

Carbonatites and alkaline rocks enriched in REE occur in a variety of tectonic settings, and any of them, provided the right climatic conditions, can develop an REE-enriched weathering carapace. This basically means that a rare-earth deposit can be found literally anywhere on any of the six continents.

There are many other factors at play here which will determine whether it is practical to look for a mineral deposit in this particular corner of the world or another. Let’s say, a fortuitous concatenation of circumstances produces a large carbonatite body in a rift setting with primary monazite, apatite and pyrochlore, which then weathers into a thick lateritic carapace hosting millions of tons of REE- and Nb-rich ore ready to be scooped up. But then circumstances take a turn for the worse and the rift is flooded by sea water. Obviously, several hundred meters of marine sediment deposited on top of our REE-Nb deposit will make it difficult to find and greatly diminish its value.

Then, of course, there are all sorts of political, economic and social factors that might attract or, on the contrary, deter potential investors and entrepreneurs should a commercially viable deposit be found, and have to be carefully thought through beforehand. For all these reasons, I would limit my exploration efforts to the well-exposed parts of North America, including both cratons and younger orogenic belts, as well as understudied investor- and mining-friendly countries with diversified geology, such as Kenya.

What has been the biggest surprise in your study of the REEs?

The greatest surprise of all was that no one has so far attempted to look at the “big picture” of REE transport and concentration, or even systematize the existing knowledge in such a way that some general trends and patterns would emerge. We have a better understanding of where and why different rocks containing leucite form than why some carbonatites are REE-rich while others are barely different from marbles, even though leucitic rocks are not nearly as economically important as carbonatites. But this just means that there is a lot of work to be done, so it was a good surprise.

How do you characterize a carbonatite?

I would like to give you an informal definition of carbonatite, if I may, simply because I have not formed a solid and inclusive scientific definition of my own yet, whereas the one given in the dictionary just does not cut it, in my opinion. Here it goes: Carbonatites are the most mineralogically and geochemically extraordinary rocks of diverse origin and often turning up where you least expect them.

What is the biggest challenge to overcome when looking at REE deposits?

I would say the greatest challenge one has to deal with when looking at a potential REE deposit is tying in microscale observations (things like replacement of one REE mineral by another or chemical variations within a single mineral grain) with large-scale parameters such as resource distribution, grade variations, tectonics, etc. Anyone who has seen a typical REE-mineralized rock will understand what I mean. There are exceptions, of course, but these exceptions are mostly among low-grade deposits which can be easily modeled, like the Lovozero loparite horizons, for example.

It takes a team of professionals with decades of cumulative experience to figure out the micro-macro connections and, ultimately, make the right call. Few other mineral commodities present the same range of mineralogical-technological problems as rare earths. For example, palladium refining is probably every bit as tricky as the extraction of individual lanthanides, but the bulk of palladium mining is restricted to magmatic copper-nickel ores and does not have to deal with problems like radioactive byproducts.

What is the most exciting thing going on in REEs today?

The recent revival of interest in rare-earth mineral deposits offers an unprecedented opportunity to advance our understanding of these deposits and beyond. By “beyond” I mean all the things that do not have any direct implications for exploration, but are important for figuring out how the Earth works.

Knowing what controls the distribution and transport of such an important group of elements as REE opens up all sorts of possibilities for studying any igneous, metamorphic or sedimentary system. For example, we have been looking at ways to discriminate true carbonatites from carbonatite look-alikes and come across some really interesting geochemical observations completely overlooked by metamorphic and sedimentary petrologists before us.

The REE boom is also exciting because it brings us to places that we would otherwise not go, and we bring along new research tools that simply were not available to our predecessors decades ago. I am really fortunate to be part of these ongoing activities, and just wish I had more students to handle the increasing amount of workload!

Have you noticed any increased interest in REEs over the past year?

Yes, I think so. It seems like 2009 was the best year so far in terms of many new companies getting into the game, old properties getting revisited and re-assessed, and new options cropping up, as well. Very few people had heard of Clay Howells or Kutessay before, and now someone will be working on both of these and many others, which is great. It is about time we steal some of the spotlight from PGM and diamonds! Mind you, I am not a business person and therefore cannot comment on how healthy the REE business is at the moment, but my dilettante impression is that it is all going very well.

What advice would you offer to a young geologist who is interested in the rare earths?

The same advice I give to every one of my students: read the literature and follow what other people in this field are doing, and do not limit yourself to technical reports or papers in Economic Geology. Look at papers describing speciation of REE in fluids and chemical variation of specific REE minerals, experimental studies simulating natural systems, explore foreign literature – look at graphs and tables, if you cannot read the language. It can be difficult at first to navigate a maze of technical terms and diagrams, but there is no way all this information can be neatly packaged and spoon-fed to you by your mentor, and most of it is relevant – you just never know when you are going to need it!

Special thanks to Dr. Chakhmouradian for helping me to understand a number of issues regarding the rare earths!