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Pyrochlore supergroup new nomenclature

Posted by Marco E. Ciriotti  
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Marco E. Ciriotti July 28, 2010 08:18PM
Reference:
• Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R., Kartashov, P.M. (2010): The pyrochlore supergroup of minerals: nomenclature. Canadian Mineralogist, 48, 673-698.

Abstract:
A new scheme of nomenclature for the pyrochlore supergroup, approved by the CNMNC–IMA, is based on the ions at the A, B and Y sites. What has been referred to until now as the pyrochlore group should be referred to as the pyrochlore supergroup, and the subgroups should be changed to groups. Five groups are recommended, based on the atomic proportions of the B atoms Nb, Ta, Sb, Ti, and W. The recommended groups are pyrochlore, microlite, roméite, betafite, and elsmoreite, respectively. The new names are composed of two prefixes and one root name (identical to the name of the group). The first prefix refers to the dominant anion (or cation) of the dominant valence at the Y site. The second prefix refers to the dominant cation of the dominant valence at the A site. The prefix "keno-" represents "vacancy". Where the first and second prefixes are equal, then only one prefix is applied. Complete descriptions are missing for the majority of the pyrochlore-supergroup species. Only seven names refer to valid species on the grounds of their complete descriptions: oxycalciopyrochlore, hydropyrochlore, hydroxykenomicrolite, oxystannomicrolite, oxystibiomicrolite, hydroxycalcioroméite, and hydrokenoelsmoreite. Fluornatromicrolite is an IMA-approved mineral, but the complete description has not yet been published. The following 20 names refer to minerals that need to be completely described in order to be approved as valid species: hydroxycalciopyrochlore, fluornatropyrochlore, fluorcalciopyrochlore, fluorstrontiopyrochlore, fluorkenopyrochlore, oxynatropyrochlore, oxyplumbopyrochlore, oxyyttropyrochlore-(Y), kenoplumbopyrochlore, fluorcalciomicrolite, oxycalciomicrolite, kenoplumbomicrolite, hydromicrolite, hydrokenomicrolite, oxycalciobetafite, oxyuranobetafite, fluornatroroméite, fluorcalcioroméite, oxycalcioroméite, and oxyplumboroméite. For these, there are only chemical or crystal-structure data. Type specimens need to be defined. Potential candidates for several other species exist, but are not sufficiently well characterized to grant them any official status. Ancient chemical data refer to wet-chemical analyses and commonly represent a mixture of minerals. These data were not used here. All data used represent results of electron-microprobe analyses or were obtained by crystal-structure refinement. We also verified the scarcity of crystal-chemical data in the literature. There are crystal-structure determinations published for only nine pyrochlore-supergroup minerals: hydropyrochlore, hydroxykenomicrolite, hydroxycalcioroméite, hydrokenoelsmoreite, hydroxycalciopyrochlore, fluorcalciopyrochlore, kenoplumbomicrolite, oxycalciobetafite, and fluornatroroméite. The following mineral names are now discarded: alumotungstite, bariomicrolite, bariopyrochlore, bindheimite, bismutomicrolite, bismutopyrochlore, bismutostibiconite, calciobetafite, ceriopyrochlore-(Ce), cesstibtantite, ferritungstite, jixianite, kalipyrochlore, monimolite, natrobistantite, partzite, plumbobetafite, plumbomicrolite, plumbopyrochlore, stannomicrolite, stetefeldtite, stibiconite, stibiobetafite, stibiomicrolite, strontiopyrochlore, uranmicrolite, uranpyrochlore, yttrobetafite-(Y), and yttropyrochlore-(Y).
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Reiner Mielke August 04, 2010 06:22PM
So what has uranpyrochlore become? Not to mention all the others?
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Reiner Mielke August 04, 2010 06:34PM
Would stibiconite now be hydroxyromeite?
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Donald Doell August 04, 2010 08:47PM
Not that I'm an expert at this or anything, but I think this is going to be a mess. I think it will be hard to ever describe many of these minerals completely as they are all prone to being metamict. Also they are mostly very rare and vary in composition within a single crystal. Also a big problem for Mindat to resolve all the existing data in the database.
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Marco E. Ciriotti August 04, 2010 09:15PM
Reiner Mielke Wrote:
-------------------------------------------------------
> So what has uranpyrochlore become? Not to mention
> all the others?


Textual from the paper:

"For all recorded cases of uranpyrochlore, U is not the dominant cation of the dominant valence at A, except for sample 9 from Khibina studied by Chakhmouradian & Mitchell (2002). Nevertheless, it is not possible to know the dominant
anion of the dominant valence at the Y site of this mineral. It should be referred as “uranopyrochlore”. Uranpyrochlore of Hogarth & Horne (1989) is “natropyrochlore”.

> Would stibiconite now be hydroxyroméite?

"Original material described by Beudant (1837). Probably “stibioroméite”. No electron-microprobe data are available. This material needs to be examined chemically and structurally."



Edited 1 time(s). Last edit at 08/04/2010 09:16PM by Marco E. Ciriotti.
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Andrew G. Christy August 04, 2010 10:00PM
Don Doell: "Not that I'm an expert at this or anything, but I think this is going to be a mess. "

It's all relative, Don. It could be argued that the previous situation was a mess, with many nearly-identical minerals given different names, many given the wrong names due to assumptions that they were the same composition as some wet analysis on another sample from 150 years ago, and many so complex that it was impossible to name them unambiguously under the scheme then operative. Even without the name changes, most reported pyrochlores needed re-examination (mainly just good-quality analysis, not structure determination). What we were aiming for was a more straightforward and logical system of pigeonholes to put them in, once that is done.
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Jolyon & Katya Ralph August 04, 2010 10:18PM
Yes, it'll be a big problem for mindat to resolve the current data, but that's no excuse to keep things the way they were.

This to me sounds like a positive step fowards to cleaning up some of the mess.

We can just switch items to the group names, it's not hard.

Jolyon
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Marco E. Ciriotti August 05, 2010 08:41AM
Yes for mindat is a problem, but the paper is very well done! My congratulations to the authors.
A little number of minerals of the pyrochlore supergroup, with relative deposited type-specimens, remain valid and change their names as in the abstract. All the others (see list in the abstract, plus betafite, elsmoreite, microlite, pyrochlore, and roméite - now only group names - and the questionable and/or non valid hydroroméite and lewisite names) are now discredited and new proposals must be presented (and approved by IMA CNMNC) to have them included in the database.

If someone needs the PDF, I can send it.
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Reiner Mielke August 05, 2010 06:31PM
Thank you Marco,

Could you please send me a copy. My email address is reinermis@yahoo.ca
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Marco E. Ciriotti August 05, 2010 07:20PM
Done, Reiner.
Enjoy!
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Gerald Allen Peters August 05, 2010 09:01PM
Marco,

Would you please send me a .pdf of the article. My email address is gpeters@cox.net

Thanks.
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Marco E. Ciriotti August 05, 2010 10:02PM
Sent, Gerald.
Ciao.

PS: Starting from tomorrow I will be in holiday for 20 days. I am sure that Jim Ferraiolo or other can send the paper in my place.
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Bela Feher August 06, 2010 09:17AM
The report can be downloaded from the IMA CNMNC home page: http://pubsites.uws.edu.au/ima-cnmnc/
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Marco E. Ciriotti August 06, 2010 11:09AM
Köszönet nagyon, Béla!
Ciao. Marco
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Reiner Mielke August 06, 2010 04:43PM
"For all recorded cases of uranpyrochlore, U is not the dominant cation of the dominant valence at A, except for sample 9 from Khibina studied by Chakhmouradian & Mitchell (2002). Nevertheless, it is not possible to know the dominant
anion of the dominant valence at the Y site of this mineral. It should be referred as “uranopyrochlore”. Uranpyrochlore of Hogarth & Horne (1989) is “natropyrochlore”.

In Ellsworth's Paper 1971, GSC. Open file report 0077, Rare Element Minerals of Canada, he gives two analysis for "ellsworthite" otherwise known as uranpyrochlore. In that analysis Uranium would seem to be dominant in the A site : UO2&UO5 18.50-19.10%,CaO 11.73-13.63%, Fe2O3 3.8-4.1%, MnO 0.22-0.43%, SnO2 0.10-0.25%, PbO 0.24-0.41%, Of course I haven't calculated the atomic proportions so it could work out that Ca is dominant assuming the classification is based on that rather than wt.%.



Edited 2 time(s). Last edit at 08/06/2010 08:44PM by Reiner Mielke.
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Reiner Mielke August 06, 2010 11:39PM
According to my calculations the ratio of Ca:U atoms in ellsworthite averages 3.68:1 ( for two analysis), therefore it is calciopyrochlore. Since the atoms in the Y site can't be determined that is the best that anyone can come up with at this time. Note: no Na was found in the analyses. Guess I have to go and change my labels.
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Pavel Kartashov August 06, 2010 11:51PM
Hi Reiner,
you'll be more correct, if you'll change the label of your ellsworthite to "zero valent dominant pyrochlore". ;)

Look here http://www.mindat.org/photo-230522.html for U dominance... :)



Edited 1 time(s). Last edit at 08/06/2010 11:59PM by Pavel Kartashov.
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Reiner Mielke August 06, 2010 11:54PM
Yes but that won't fit on my label!
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Reiner Mielke August 07, 2010 12:38PM
Now for the really bad news, Betafite is no more! With this new classification system only samples from the moon have so far been found to fall in the Betafite field. The type material from Madagascar and all terrestrial "betafites" are now calciopyrochlore, which in itself is not a species name but a subgroup name. The species cannot be determined for metamict samples because the dominant ion in the Y position cannot be determined, which is necessary to define it as a species. If you do want to distinguish the old "betafites" from the other calciopyrochlores ones you will have to call them uranium-titanium rich calciopyrochlore.
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Rock Currier August 08, 2010 02:08AM
Another endearing communication from the IMA.

Rock Currier
Crystals not pistols.
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Pavel Kartashov August 08, 2010 11:44PM
Reiner,
again the same error. Most of U-bearing betafites aren't calciopyrochlores but "zero valent dominant pyrochlores". See composition of Madagascar betafite groundmass - http://www.mindat.org/photo-230522.html

Besides that you aren't correct in the your statement about exclusively Lunar nature of real betafites, I have specimen of hydroxylnatrobetafite from syenite-pegmatite of Kovdor Mica Mine with composition (Na0.98Ca0.34(Ce0.14La0.10Nd0.01)0.25Th0.14Sr0.07)1.78(Ti1.16Nb0.82Ta0.02)2O4.45(OH)2.55 - former "thorian betafite of Kovdor". So finds of real betafites are possible on the Earth. We only should to find them.

By the way, even being the coauthor of the article, I am not happy with its results. With this nomenclature mineralogy lost too many, but obtain very little and in far undetermined future. :(
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Jeff Weissman August 09, 2010 03:35PM
Hi Pavel

Do you know what the pyrochlore species are at the Enisie Range locality?
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Pavel Kartashov August 09, 2010 04:48PM
Hi Jeff,
you had means Tatarka pyrochlores from Enisei Range http://www.mindat.org/photo-284496.html? I think they are fluorcalciopyrochlores.
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Jeff Weissman August 09, 2010 06:31PM
Yes, thank you!
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Lefteris Rantos August 17, 2010 02:10PM
Pavel,

What about the "plumbomicrolites" from Ploskaya Mt, like http://www.mindat.org/photo-1175.html and http://www.mindat.org/photo-213233.html ?

And the classic "pyrochlores" form Vishnevye Mts, like http://www.mindat.org/photo-71869.html ?

Lefteris.
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Johan Kjellman August 18, 2010 06:59AM
according to Atencio et al. (2010) who refers to Bindi et al. (2006b) the plumbomicrolite from Ploskaya is "kenoplumbomicrolite"

cheers
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Peter Haas October 24, 2010 04:07AM
"Not that I'm an expert at this or anything, but I think this is going to be a mess."

Pyro-gore, so to say ?
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Edgars Endzelins July 24, 2011 11:53PM
What should Ceriopyrochlore-(Ce) be called?
I don't see any Fluorceriopyrochlore.
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Marco E. Ciriotti July 25, 2011 05:36AM
Name discredited by 2010 Pyrochlore Subcommittee; may be fluorkenopyrochlore or Ca- or zero-valent-dominant pyrochlore.
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Pavel Kartashov July 25, 2011 07:50AM
According to general trend of mineral-formation Ceriopyrochlores form in environments depleted with fluorine, and F in their composition is residual. So, if we will found LREE-dominant pyrochlore group member, it will be rather Hydroxylceriopyrochlore.
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Harald Oskar Folvik October 14, 2012 10:56AM
Marco!
Can you please send me the paper?
my adress is h-o-f@online.no

Harald F.
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Marco E. Ciriotti October 14, 2012 01:30PM
Sent, Harald.
Cheers.
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Alexandr E. Zadov October 14, 2012 02:50PM
Привет!
Считаю новую номенклатуру суппер-группы пирохлоров грубой ошибкой IMA и вредной для Геологии в целом. Считаю необходимым вернуться к старой версии. При всех её недостатках она более соответствует Геологии. Лично я в коллекции никакие этикетки у этих минералов менять не буду.
Минералогия - не должна быть консервной банкой, привязанной на хвосте кристаллохимии
Минералогия и Кристаллохимия решают разные задачи. Поэтому систематики
объектов их изучения и должны быть разными. Например: Кристаллохимии нет смысла делить плагиоклазы на много частей. Им хватит альбит-анортит, а Минералогии надо делить этот ряд на несколько частей.
А.Е.

I apologize for the machine translation
Hi!
I think the new nomenclature of supergroup pyrochlores mistake IMA and harmful to the geology in general. I believe we must go back to the old version. For all its shortcomings, it corresponds more closely to Geology.
Personally, I am in no collection boxes around these minerals will not change.
Mineralogy - should not be tin can tied to the tail of the crystal
Mineralogy and crystallochemistry solve different problems. Therefore, systematics objects of their study and should be different. For example, a crystallochemistry does not make sense to divide into many parts plagioclase. They have enough of albite-anorthite, and Mineralogy of the series should be divided into several parts.
A.E.
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