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A general guide for using the Forum with some rules and tips
Certificates of authenticity for analyzed rare mineral specimens
  
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Bob Harman




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PostPosted: Jul 27, 2019 18:40    Post subject: Certificates of authenticity for analyzed rare mineral specimens  

Dealers and collectors of rare stamps and coins (often very pricy) routinely require certificates of authenticity, including a photo of the specific example, when purchasing or selling a specific example. This, of course, facilitates the sale and purchase of the specific example.

For those collectors of rare and very rare mineral species, often quite small in size, is a paper copy of the specimen's assay enough to facilitate the sale or purchase? Might the assay paperwork include a specific specimen description or do current specimen assays routinely come with photos certifying that the assayed specimen is one and the same as the example being bought or sold?

BOB
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mmauthner




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PostPosted: Jul 29, 2019 05:48    Post subject: Re: Certificates of authenticity for assayed rare mineral specimens  

Hi Bob, and All,

An interesting topic and one to which, for many reasons, I have also given some thought.

The first question one might ask is Why? Why is there a need for such a certificate?

First, there is enough room for error or even downright fraud in extistence in the marketplace that trust is an issue for many collectors.

Second, species determination, especially for newer species, is now commonly the result of ever more complex anaytlical methods. (Complete aside: Bob, I recommend the usage of the word 'analysis' instead of 'assay'. An assay is a type of analysis to determine the amount of something particular in a sample; in mineralogy-economic geology this generally means the amount of an economic material in the sample, e.g. gold in an ore.) Determining the exact species of a specimen has become rather a challenge for most collectors, especially those with no access to the sophisticated technology necessary to differentiate like species. For example, the number of people on this planet that have the knowledge and equipment to determine the exact species of an amphibole can be counted on one's digits. Then there is the ever-moving target of species definition: the tetrahedrite group is a good example...freibergite, anyone?

The second question one needs to ask is Who? Who gets to produce these certificates? What authority is comprehensive enough (labratory equipment, personnel with appropriate experience) to accurately describe every mineral? What lab does not make mistakes? Look at the list of discredited mineral species of late. How many people have had the experience of taking a specimen to various labs that then produce different results?

The third question: Is it worth it?
For one, the cost of making analyses is not insignificant. How much is that micromount worth? What does it bring the collector to know that this microdot is exactly X-microdot and not Y-microdot. What about 'ball-park' analyses? How valuable are they? Granted, if it ends up new, you might get your name on it...that could be worth something to some. Yes, the collector might want to ascertain that the orangey-straw tuft of needles truly is labuntsovite from Mont St. Hilaire and not a similar appearing species from the same locality.
Secondly, does the market bear the additional cost in specimen price? If after having paid $XXX, is that cost going to be covered by the next person who wants to possess that specimen? Maybe. I would certainly say that a specimen with an accompanying analysis is worth more than a similar specimen without one, but is it worth it to a dealer to have every specimen analyzed? For some of the super rare species that I am sure you are eluding to, probably so. That would also mean *every* specimen must be analyzed, not "this piece comes from the chunk that XX species came from". The certificate must accurately describe the specimen such that it cannot be exchanged for another, along the lines of many gemstone certificates. Coin graders get around this by encapsulating the graded coin, but this in turn, and thirdly, creates another consideration (problem, in my opinion). Coin 'slabs', as the are known, totally turn me off. It is like owning a 246 GT Ferrari and leaving it in a hermetically sealed showroom. I would want to own one not to *own* it, but to drive it, and drive it like it was meant to be driven. A mineral specimen in a sealed box is next to uninteresting to me. I am not sure one would have to go that far for minerals, but it would only take the first lawsuit (because we are talking about money here) to challenge the specimen-certificate validity to bring some 'security feature' like that about.

Anyway, it would be an interesting direction for mineral collecting to take.

By the way, my thoughts on a certification process for minerals were less focussed on the actual identity of the species (e.g. fluorite is generally a no-brainer), but more on:

1) How natural is the specimen? Is it a fake?
2) If natural, what has been done to the specimen since it left the ground? Cleaning, repairs, restorations (where, what, how?)

I have no problem if collectors knowingly desire and purchase 'enhanced' specimens because aesthetic is their primary goal. I do consider the selling of such specimens as 'completely natural' as unethical. I also have no problem with using advanced display techniques to enhance specimens...but in the selling of such specimens, such techniques must be disclosed. Buyer may not know about the enhancement. That is part an parcel of educating the buyer/collector. Some might argue that it is up to the collector to educate him or herself, but where is the average and especially beginning collector really supposed to learn that? I have the impression that most collectors, especially at the high end market, where so much more money is at stake, are relying on dealer information. Dealers that are open about specimen treatments, especially in documenting them, are worthy of a collector's trust.

But back to your thoughts on identification certification...a reliable certification program would certainly allow species collectors to be more comfortable in their acquisitions. To answer your question more succinctly, any such certificate would in fact have to include a very specific specimen description. Supporting evidence, such as an SEM graph or microprobe results, structural analyses would have to be included on the certificate. The original output from the analytical machine is not enough to validate the relationship between analysis and specimen. Have a look at a gem certificate (e.g. GIA diamond certificate, or an AGL origin report).

Best regards,
Mark Mauthner
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Bob Harman




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PostPosted: Jul 29, 2019 09:33    Post subject: Re: Certificates of authenticity for assayed rare mineral specimens  

Mark M,

Thanks for your well thought out reply. From now on "analysis" it will be.

Much of what you say I agree with. One basic difference in collecting rare stamps or coins and collecting rare minerals is that with most rare stamps and coins there is a well known number of each specific example out there, while with minerals, even tho rare, there is an unknowable number and variety of examples. With classic rare stamps and coins most come with a recognized provenance. Thus groups of experts are available to evaluate stamps and coins, but even with extensive mineralogical training, an expert review committee, having access to all manner of analytical equipment, might be more difficult to assemble to evaluate each submitted rare mineral specimen for certification. Maybe???

Personally, I do not collect rare minerals, micromount size or cabinet size, $X or $XXXXX, for the very reason that there is no recognized certification process for each individual specimen. All transactions seem to basically take place by knowing the "ethical" buyer/seller and some more or less generic analysis paperwork and a shake of the hand. Just not enough protections or "standardizations" for me to consider this subtype of mineral collecting. BOB
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alfredo
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PostPosted: Jul 29, 2019 10:28    Post subject: Re: Certificates of authenticity for assayed rare mineral specimens  

In my youth I wanted to have at least one of every known mineral so, although I didn‘t know the term at the time, I was a "systematic species collector". After a few years it became evident that the goal of having every species was impossible, and in fact receding further and further away, as new species got described faster than one could acquire them. As Rock Currier said, it‘s only fun if your "want list" is getting shorter, and Rock was immensely proud of himself when his want list got down to about 700 species which, by using a very small font, he could print up on a single sheet of paper. But the rate of discovery of new minerals is faster now than it was then, and many of them are invisibly tiny, so most collectors‘ "want lists" are getting longer instead of shorter, and then it isn‘t fun anymore.

So now I only collect those rare species that are interesting to me, and most of the ones I find "interesting" are sufficiently visually distinctive, or elementally distinctive, that I don‘t worry about whether the species is present on my piece - If it isn‘t obvious, then I don‘t want it anyway. But still, I‘ll take a 1 millimeter size minakawaite over the world‘s finest calcite specimen any day.

Like any hobby, with knowledge comes power. God help the beginner who can‘t tell an amethyst from a purple fluorite. Systematic species collectors must of necessity know a lot more mineralogy than the average collector. Then the analysis is often just a confirmatory backup for what one already knew from the appearance of the mineral, its associations, its matrix, and its provenance. And the number of criminal dealers who deliberately cheat their customers by selling common minerals with rare names on the label is luckily a very small number (I can count them on the fingers of one hand), and they are well known to anyone who has been in the hobby for long.
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mmauthner




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PostPosted: Jul 29, 2019 11:36    Post subject: Re: Certificates of authenticity for analyzed rare mineral specimens  

Hi Bob,

The difference you mention is true. I did not catch your meaning there from your first post. I understood you were just talking about a certificate of authenticity; in other words, something that says "this specimen has X species on it" and possibly "it comes from So-and-so-hole-in-the-ground".
I don't think there is a way to grade specimens or give a scale of rarity for minerals in general because it is too ephemeral. It would change too much as new discoveries are made. That is somewhat the case for a few ancient coins, but for most and certainly modern coins, you are correct that dealers and collectors have a good handle on rarity, and grading, while borders may be arguable, is at least doable. It is also doable, and is done, for gems, the grading, I mean...rarity is another issue.

Mark
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Pete Richards
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PostPosted: Jul 29, 2019 19:04    Post subject: Re: Certificates of authenticity for analyzed rare mineral specimens  

To follow up on Mark’s excellent essay, I offer the following recent experience. I have a sample from Mont Saint-Hilaire which has several crystals of either hiortdahlite or wöhlerite. Collectors usually distinguish between the two on the basis of morphology and color, but these cannot be totally trusted. I mounted small samples from six different crystals and studied them with EDS (Energe Dispersive Spectroscopy, a technique that determines chemistry). I made a total of 42 analyses of different spots on these samples. The analysis gets pretty technical, so the bottom line is that almost none of the analyses matched the standard formulas for either mineral. If you like, you can stop here – or read on!

By the standard published formulas,
hiortdahlite is (Na,Ca)2Ca4Zr(Mn,Ti,Fe)(Si2O7)2(F,O)4
and wöhlerite is Na2Ca4(Zr,Nb)2(Si2O7)2(O,OH,F)4
(I doubled the formula for wöhlerite for ease of comparison).

The formulas are very similar – each has a total of 6 Na+Ca cations (call them “A”) and 2 other “B” cations (these are not meant to represent formal structural sites), in addition to 2 Si2O7 groups and 4 (O,OH,F) groups. In hiortdahlite, two of the A cations can be either Na or Ca and the rest are Ca, so it can range from Na2Ca4 to Ca6 as extremes. Wöhlerite, on the other hand, always has Na2Ca4, according to the formula. Similarly, hiordahlite has a B group with one Zr and one other cation that can be Mn, Ti, or Fe, while wöhlerite has both B cations either Zr or Nb.

We can construct two indices of composition using this information, and use them to display the analytical results in comparison to the ideal compositions, as in the graph below. One index is the measured abundance of Ca, as a percent of the abundance of Na+Ca. With this index, wöhlerite has a value of 67% and hiordahlite can range from 67% to 100%. The other index is the abundance of Zr+Nb as a percent of the abundance of Zr+Nb+Mn+Ti+Fe. With this index, wöhlerite has a value of 100% and hiordahlite has a value of 50%. We can then plot each analytical result and the theoretical pure species on a two-variable graph using these two indices. Hiordahlite is shown as a line, reflecting the fact that its Na+Ca value is variable.

The results are revealing. Only one analysis conforms closely to either of the pure species, though several others are within 10% of the hiordahlite line. No analysis is within 10% of the wöhlerite position, even though this sample was originally identified as wöhlerite. There are some small clusters of four or five analyses that are suggestive of something, but investigation shows that these are in no case analyses on just one crystal, as might be hoped. There is almost no correlation between the values of the two indices, which means they are measuring independent aspects of the crystal chemistry (in this case, this is actually good).

One way of dealing with these results is to say that we can’t tell these two species apart on the basis of chemistry, and to just call the specimen hiortdahlite/wöhlerite. Another would be to draw a line at 75% on the B index (half way in between hiortdahlite and wöhlerite) and divide the crystals into the two species on that basis – though that would lead to the result that some individual crystals contain both species.

Hiordahlite is triclinic, and wöhlerite is monoclinic. One could insist on x-ray results to determine which is which. The Raman spectra of the two minerals are quite different, so there’s another way to tell them apart. But can we be sure that those two methods would yield the same result, and would be in some kind of accord with the EDS results?

My little study actually produced quite a lot of information. It is just not useful in trying to compel the specimen to be one species or the other. Echoing Mark’s comments, then, trying to certify the “authenticity” of a particular specimen is likely to be an expensive undertaking, probably not realistic except for very rare and/or very valuable specimens. And even then, there is the possibility of contradictory or unsatisfying results using different techniques.

Species are presented as distinct realities, but nature is often much less clear-cut!



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PostPosted: Jul 29, 2019 19:46    Post subject: Re: Certificates of authenticity for analyzed rare mineral specimens  

Peter's study is interesting. A rare mineral collector acquires a rare mineral specimen. Exactly how it is acquired, while important, is far from foolproof and the price is irrelevant. Many times the species is identified correctly, but other times it is not correctly identified. Precisely my point! In some cases, without some type of certificate of authenticity, the collector of rare minerals really does not know what he/she is acquiring. BOB
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alfredo
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PostPosted: Jul 29, 2019 20:29    Post subject: Re: Certificates of authenticity for analyzed rare mineral specimens  

Continuing in my role as wet blanket and general all round curmudgeon...
A "certificate of authenticity" is only as good as the amount of study that goes into it. Sometimes an EDS analysis is enough. Very often it isn‘t. Sometimes X-ray diffraction is enough, but often it isn‘t. Sometimes, especially with big complex groups like the tourmalines and amphiboles, or the acicular sulphosalts, one can get BOTH an EDS and XRD analysis, and still not be sure which species one has, unless one of the half dozen mineralogists in the world who specialized in the group looks at it, other mineralogists need not apply. So just establishing one lab somewhere to "authenticate" minerals won‘t be enough. One needs to also know WHO did the analyses, how much they‘ve studied the group in question, and whether they used the most appropriate equipment for the type of species... in other words we need TWO layers of certificates - your Certificate of Authenticity, with attached analyses, then a Certificate of Competency from a more academic institution certifying that the analyses used, and the analyst, were adequate for the specific task. Then add $250 to the price of the rock to pay for all this. The amount of study Pete described above would cost a lot of money if done commercially.

Of course, I‘m being a bit absurd here, and the economics dictate that it isn‘t going to happen. Yes, one could afford to do this for $1,000 specimens, but systematic species collectors don‘t buy rocks in that price range, usually. They buy rocks in the $30 to $300 price range. The people who buy $X,000 rocks are buying beautiful splendid examples of common minerals, for the most part, for which the ID is usually obvious and no analyses required. So, I go back to my previous opinion, that analyses can be very helpful in some cases, but from the point of view of the specimen market (in our little niche market of rare mineral species) it is equally or more important for the buyer to educate himself about the species he‘s acquiring and its locality, the geologic environment and associations, and the provenance of the specimens, cultivate good relationships with dealers who share all necessary information, and then decide whether an analysis would be helpful in the particular case or not, and which equipment would be best suited to the task. If a buyer requires some bureaucratic type of certification, they‘re probably better off collecting gem crystals or agates and not rare species.
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