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Improving Mindat.orgUnsubstantiated claims

21st Jan 2015 17:40 UTCReiner Mielke Expert

http://www.mindat.org/photo-660886.html and you know this is Raguinite because?

21st Jan 2015 17:59 UTCRob Woodside 🌟 Manager

There were a couple of Allchar Tl mineral photos I approved because they look like those minerals. However without analysis you can't be certain. There are lots of approved visually identified rare sulfides that can only be known with certainty by analysis. This is big problem and previously I have been asking if the mineral was analysed and asking people to put "unanalysed" in the caption. It is a lot less work to assume that anything posted is unanalysed, unless it it says "analysed" in the caption. Then there's the problem of how it was analysed and by whom which should also mentioned in the caption. What to Do???

21st Jan 2015 19:04 UTCAlfredo Petrov Manager

Even specimens that are "analyzed" are not necessarily correctly labelled. There are many sources of error - analysis methods inadequate for the task, analytical results misinterpreted, photos showing a different part of the specimen than what was analyzed, specimens and labels accidentally mixed up.... In my experience an unanalyzed rare species has a 30% chance of being wrong and an analyzed one has a 20% chance of being wrong. Two analyses, using different methods, increases the chance of correctness. We live with a certain degree of uncertainty and our goal is to reduce the uncertainty, but it is never eliminated, even for minerals from "reliable source" with "analyzed" on the label. (Please forgive my philosophical rant.)

I did not approve the photo in question here, but when I am approving photos I generaly give the photographer the benefit of the doubt and assume their ID is correct, unless I see some specific reason to doubt it (wrong appearance, unlikely association, notoriously unreliable source...).

21st Jan 2015 19:22 UTCRob Woodside 🌟 Manager

Alfredo says. " In my experience an unanalyzed rare species has a 30% chance of being wrong and an analyzed one has a 20% chance of being wrong."

From my limited experience I would raise Alfredo's 30% to more like 50% or higher and lower his 20% to 5% or less. Occasionally there are real howlers, like the wrong polymorph being identified by EDS, etc., but these are outliers and one of the reasons why 'whom and how' needs to be given in the captions or when adding a mineral to a locality.

Reiner, you do a lot of analysis. Do you think things are as bad as Alfredo suggests?

21st Jan 2015 19:49 UTCAlfredo Petrov Manager

It depends on the type of mineral one is working on. Some mineral groups are fairly easy and then I'd expect a very small error rate. Some are notoriously difficult, like tourmalines, amphiboles, and fibrous sulphosalts, where one can have both a powder XRD and EDS probe results and still sometimes be wrong, even when the tests were performed by a professional mineralogist (I won't mention examples so as not to embarrass anyone). For those most difficult groups you can really only trust results when the analyst was a specialist in that particular mineral group, and even then you run across cases where they change their minds later.

We will always have to live with some uncertainty (which we strive to diminish). Those who insist on everything being absolutely black or white are going to have a great deal of frustration in mineralogy. There are so many young collectors who still live in a fantasy world of "This must be mineral X because it was analyzed!"

21st Jan 2015 20:17 UTCRalph S Bottrill 🌟 Manager

It's disturbing but probably true; I would have given numbers somewhere between you both but what can you do but be sceptical?

21st Jan 2015 21:20 UTCFrank Keutsch Expert

Alfredo is right that for some groups it really can be difficult. For fibrous sulfosalts one crystal may be different than another or even worse a crystal consist of many different minerals. We are battling one such example where a beautiful 2mm crystal corresponds to something like 5 different minerals...

However, there are many cases, where analysis should be reliable.

I don't have any valid raguinite. All samples I got were just iron-sulfides in various stages of decay, including ones that looked exactly right!

The problem is knowing when this is the case.

Frank

21st Jan 2015 23:50 UTCRichard Gunter Expert

Hi Frank:

The RRUFF database has many examples of multi-phase crystals, especially among the sulphosalts. I like the one of the Mina El Cobre Tennantite-Tetrahedrite where multiple layers of varying chemistry have been deposited to make a euhedral crystal. In cases like that there is not even a name to call the crystal as it has so many distinct phases within it. Even XRD would not give an adequate answer to that texture, only elemental mapping would show the complexity.

22nd Jan 2015 00:14 UTCReiner Mielke Expert

I do not expect every sample shown on mindat to have conclusive proof that it is what it is supposed to be. However for the very rare species I think there needs to some proof. I don't think I can make a statistically significant remark as to the percentage of samples that are misidentified as I am careful about what I buy. If there is no way I can verify something without expensive analysis I won't buy it so my data is biased. All I can say is that it is not uncommon to find samples that have been misidentified.

22nd Jan 2015 03:27 UTCAlfredo Petrov Manager

I agree, Reiner. Every photo uploader should be strongly encouraged to include in the photo caption some details about how the species was identified, al least for those minerals whose identity is not visually obvious. We should remind them periodically that if they do not do this, then there is a much higher probability that their photo will be questioned, or assigned to their "user only" gallery out of public view.

22nd Jan 2015 10:37 UTCUwe Kolitsch Manager

"In my experience an unanalyzed rare species has a 30% chance of being wrong and an analyzed one has a 20% chance of being wrong."

For me, it's 40-60% and 20-40%, respectively. Haven't made any statistical evaluation, though.

22nd Jan 2015 16:18 UTCFrank Keutsch Expert

The % of misidentification, in my opinion, really varies but sadly increases with increasing rarity: I just analyzed a bunch of rare minerals I recently purchased. Not one of them I could actually find. I have to agree that it would be nice to see some proof for the really rare species.

A typical case is sorbyite, which one can obtain samples of from Candelaria/Nevada, Sweden and other localities. Our work showed that none of the samples we got contained sorbyite as far as we could tell. For the Candelaria material what we found was a fine intergrowth of common minerals. With superficial EDS of unpolished samples the chemistry actually was fairly close to sorbyite! There are many similar cases.

Anyway, just thought I would chime in with this and support showing proof for vary rare minerals...

Frank

22nd Jan 2015 16:33 UTCReiner Mielke Expert

I would rather see fewer pictures of verified specimens than a lot of unverified ones. Maybe Mindat should have a policy of only allowing pictures of rare species if there is some proof such as EDS supporting the conclusion ( but not necessarily conclusively proving although that would be preferred). All other photos should be in the posters personal folder only. It may encourage people to get analysis done on their samples thereby improving the quality of the database. Furthermore I would also like to see the analytical results not just a statement that it was analyzed. This is very useful for comparison purposes of ones own analysis.

22nd Jan 2015 17:02 UTCRob Woodside 🌟 Manager

I think that Sorbyite was a Sid Williams find and I always wondered about it. Should we mark it erroneously reported? Once something is reported one should be looking at the material analysed for the report to be sure that the report is in error. Looking at similar material and not finding the reported mineral can be attacked by saying you just are unlucky and haven't found it yet. However, when one sees that a poorly prepared EDS without the mineral gives similar results then at least the report can be marked questionable. Frank do you know which of the two Nevada Sorbyite localities your pieces came from?

Gary Ansell used to buy specimens for the geological Survey of Canada and returning to Ottawa, Andy Roberts would x-ray them. At one species dealer's room Gary would go around checking labels and selecting specimens. When it came to settling up, the dealer, who knew Andy would check the pieces, started pulling them out of the flat saying, "I don't think you'll want this one. or this one, or..." About a third to a half of the selected specimens were removed. Even then Andy often couldn't find the supposed species.

22nd Jan 2015 17:41 UTCNorman King 🌟 Expert

I have concluded that usually the claim of analytical verification actually refers to an analysis having been done on some sample(s) from the locality rather than for any particular specimen (such as the one you just bought!). You have to at least study the sample to find a legitimate candidate for that mineral based upon reported physical properties, mode of occurrence, and habit. If you can do that, I would say that such specimens could be posted in the gallery. Otherwise, by the law of supply and demand, the already expensive process of having analyses done would skyrocket, and people would no longer be interested in playing this little game.

22nd Jan 2015 18:30 UTCFrank Keutsch Expert

Rob,

the specimens either stated Candelaria mine, or simply Candelaria. The problem is exactly as you state. Our work does not prove at all, that sorbyite does not exist there. However, it did not in our samples. I am fairly skeptical of any of the pictured sorbyites from there, but obviously I have no proof of this, and I am merely stating an opinion.

The issue I see is, who gets to decide whether a mineral is rare enough to require some form of proof. For sulfides and sulfosalts I have my own experience but it is clearly not objective due to the limited dataset.

Here is the list of rare minerals I could not find in my last analytical run:

- shandite

- argentotennantite

- tischendorffite

- sederholmite

- nowackiite

- nisbite

- garavellite

- berthierite (not really rare but it was zinkenite)

- koutekite

- argentotennantite (other locality)

- moschellandsbergite

- stromeyerite

- laffitite

The ones that were correct:

- samsonite

- germanocolusite

- clausthalite

- villamaninite

- hauchecornite

- anilite (probably)

- guanajuatite

- arsenohauchecornite (who was that one from I wonder!!)

- krennerite

- galkhaite

Anyway, just some observations...

Frank

22nd Jan 2015 20:13 UTCHenri Koskinen Expert

Analytical data can be added as a photo of the type "analytical data" but I don't know if there is any way to search for it. After uploading it is classified as "Miscellaneous photo". Also it is not shown as a child photo icon. One has to go through one by one the photos and open their captions to see if there is a child photo of the type "analytical data".

Henri

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24th Jan 2015 04:21 UTCRock Currier Expert

I would think that eventually the mineral image upload page could contain a field or check off list of choices Like. 1. Well that's what the label said with a field saying whose label it was., 2. Visual ID, 3. Method of ID to say whose ID it was and what method was used. Ideally we could have several of these lists tailored to show up on different kinds of minerals. Rare minerals could have Well that's what the label said check box but below that would caused placed a disclaimer that would appear in the caption area of the image saying that such and such a mineral is not easy to verify and that the viewer might wish to keep in mind that the identification of the above image might be in error. If the Method of ID box was filled out and appeared to verify that the mineral show was correct, that information could be appended to the caption. These cautionary sentences in the caption would be at least as useful as the note that says that the mineral is not currently recognized from the deposit.

24th Jan 2015 04:54 UTCMatthew Stanley

Reiner Mielke Wrote:

-------------------------------------------------------

"It may encourage people to get analysis done on their samples thereby improving the quality of the database."

I'm really liking this thread, but this sentence caught my eye. I am not a scientist. I am not a dealer. I don't collect "high end" specimens because I can't afford them. Where can an average Joe go to get a mineral analyzed, and how much would it cost? Seems to me like it would only be worth it for really expensive specimens.

Was this statement meant to exclude us average Joes from contributing to the database? If not, that's fine, but that's how it came across. If I'm wrong and an analysis is only a few bucks, then I'll gladly start analyzing my collection.

24th Jan 2015 05:06 UTCRock Currier Expert

Someone should write an article about how in general minerals are identified and for more complex ones, who can identify them and the cost of doing so. There should be a chapter on what a mineral is and what a rock is a discussion about the likely hood of someone correctly identifying a particular massive bit of mineral or rock from a photo.

24th Jan 2015 14:31 UTCReiner Mielke Expert

Hello Matthew,

A basic EDS analysis is $10 US and is available to anyone here: http://kaygeedeeminerals.com/sem-eds_service If you want a more thorough and detailed analysis I would recommend this for $40:http://www.attminerals.com/mineral_identification.htm : This desire for analysis only applies to rare species which most collectors are not likely to encounter or be interested in (because they are not usually very attractive).

24th Jan 2015 15:48 UTCChester S. Lemanski, Jr.

One of our advertisers does X-ray work rather affordably - Attard. Check them out.

24th Jan 2015 16:38 UTCFrank Craig

Hello Mathew/Reiner:

I have been following and have taken an interest in this thread. Most common minerals do not "need" analysis beyond their physical properties as the necessary proof. There are exceptions to this, such as the amphiboles and perhaps the pyroxenes - physical properties alone will not always help with the mineral species. Chemistry (and atomic structure) is essential to the amphibole classification, for example. I want to point out that EDS (alone) cannot always provide the necessary accuracy for such "proof". You have to be careful when choosing a person/lab to do the work, especially if you are not familiar with the technique. There are differences in the way detectors are designed as well as each manufacturers software used in displaying and interpreting the spectra (this applies to the operator as well).

Having said that, both Reiner and I know that EDS can be an indispensible aid in the identification of a mineral. So, I guess the major point here is to be very selectful of which minerals you want to have analysed as well as the person/lab doing the work. Otherwise you could end up spending excessive amounts of money for someone to tell you something that you already knew, or for data that is misleading.

I hope this is some help.

Regards

Frank

24th Jan 2015 17:08 UTCMatthew Stanley

Reiner and Frank -

Thank you for the replies. It is far cheaper than I was expecting. I will have to do some further research on this and perhaps take advantage in the future. Thank you for such an educational thread!

24th Jan 2015 17:50 UTCFrank Craig

I suppose I should add the following "plug" for KGD minerals (and I usually don't do this): I have dealt with him in the past. The identification of all the minerals I purchased was spot on. I was even able to duplicate some of his analyses. The only possible negative I could say is that he didn't have a light element detector (he might have one now). I would recommend his service.

24th Jan 2015 19:31 UTCAlfredo Petrov Manager

And I'll put in a plug for John Attard's analytical lab in San Diego, a service I've used several times and been very satisfied with: attminerals.com

It's more expensive ($40) but a bit more reliably quantitative. He also does PXRD (powder X-ray diffraction) for the same price (for which you need to provide a sample about half the size of a grain of rice), and results usually come within 48 hours. He can also check the presence of various elements by wet chemistry and by arc spectroscope.

It should also be noted that many collectors get specimens analyzed free of charge by mineralogists at universities or museums. The disadvantage of that is that mineralogists at public institutions tend to be very overworked and often will sit on your specimen for months before doing the analysis, or may never do it at all unless it happens to be from a locality or a mineral group that they are particularly interested in. If you want fast results, it's better to use one of the commercial services.

24th Jan 2015 20:51 UTCTony Nikischer 🌟 Manager

Sid Williams first identified sorbyite from the Candelaria occurrence in November, 1973. I have his original X-ray data sheets, and his powder pattern results were excellent matches for sorbyite. He was originally trying to confirm an identification of jamesonite, and he, too, found many admixed phases in this material. Hence, it wasn't pure material then, either, but there is some solid analytical data that supports the identification.

I must agree with others that EDS is an excellent tool to aid in identification, and it used in my lab on a regular basis. However, complex minerals may often require two or more analytical techniques to unequivocally identify the phase. The skills of the operator (both mineralogical as well as technical) are important, as is the suitability of the type equipment being used for the specific mineral. Two articles appeared in Min Rec years ago (one on XRD and one by yours truly re: EDS and WDS) that are still useful today. The emergence of Raman and other techniques, along with the construction of accurate databases, are game-changers today.

26th Jan 2015 18:02 UTCRob Woodside 🌟 Manager

Thanks Tony. So it was there! I think the problem is with the Statistically Present specimens which came from the locality and were the right rock type, but had no confirmed species. These are still floating around for Frank to analyse.

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