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Allanite-(La)?
  
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lluis




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PostPosted: Nov 22, 2007 14:04    Post subject: Allanite-(La)?  

Dear List

I asked Jordi if I could place this topic, that I answered in Mindat

https://www.mindat.org/mesg-7-80457.html

also here in the Forum. Jordi graciously had permitted me to place...

It is about a question on the allanites-(La) from Burguillos del Cerro, Badajoz, Spain.
I was quite shocked when I read "I was in a quiet idiocy when I saw...." and then I supposed that I should answer...Those issues, if not cleared from the beginning, at the end are so convoluted that no one knows nothing....., in my humble opinion...(or perhaps it is that I am a Spaniard of hot blood.... :-) )

Dear Mr. Kartashov,

I was quite surprised for the commentary about the allanite-(La) from Burguillos del Cerro. Jordi Fabre placed already a quotation on a MR article about this subject.

I have it now in my hands, and as I recall, the analysis showed from 9 to 22% REE oxides, which places them apart from an epidote. You being an expert in those minerals, surely you know Mr. Del Tánago and Mr. Saiz de Baranda. They find that the REE oxides vary inside the crystal, but with a minimum of 9% in the poorer part. And that qualifies the species to be named allanite.

Because of the discrepancies between your analysis and those published in MR, and also the mention you make about "green epidote crystals", I would think that you are not analyzing the allanite-(La) from Burguillos del Cerro. It is jet black, without the faintest trace of green.

I would then think that you perhaps are analyzing an epidote from Burguillos del Cerro, that exists also and that are green. But taking in account that the authors I quote, Mr. Del Tánago and Mr. Saiz de Baranda state clearly that this epidote is free of REE, I fear that perhaps you are analyzing an epidote from another occurrence.

If you want, I suppose that I could send you a sample for the pertinent analysis.

But I fear that I should disagree in that statement that "would be ridiculous if it was not sad". I fear that you have analyzed God knows what, but not an Allanite-(La) from Burguillos

With best wishes

Lluís

P.S.: If you could read Spanish, that could be interesting
https://www.fabreminerals.com/forum/Foro-Mensajes/viewtopic.php?t=269
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PostPosted: Nov 23, 2007 06:24    Post subject: Re: Allanite-(La)?  

Apparently some clarification of the history of this dispute is in order for Forum readers because it relates to a lengthy thread which appeared on the Mindat Message Board, which one can access from the link provided. It appears to have come about because Lluis (or someone) submitted a photo of alleged allanite-(La) from the Nueva Vizcaya mine, Burguillos del Cerro, Badajoz, Spain, to accompany the description of allanite-(La) provided by Mindat. Actually there are several photos of allanite-(La) shown by Mindat so it is not clear which is that of Lluis. In any case, Pavel Kartashov appears to believe that the crystal(s) illustrated in the photo(s) are essentially epidote, not allanite-(La), in spite of the fact that this material has been analysed and described in a published paper by J. Gonzalez de Tanago and B. Sainz de Baranda Graf (Mineralogical Record, v. 33, pp. 489-500,2002). These authors did indeed find that some of the material analysed is allanite-(La), but only microzones within the crystals have this composition and that most of the rest of the crystals is epidote.

Therefore, I am assuming that Kartashov's complaint is that one should not present a photo of what is essentially an epidote crystal and call it allanite-(La), even if tiny zones within it are rich enough in La to make them allanite-(La). If my interpretation of this issue is correct, then I find I must agree with Kartashov, even if I find his use of words like "idiocy" and "ridiculous" to be unnecesarily insulting.

I hope I have done justice to both combatants in my review of this dispute. The argument is somewhat hard to follow because English is not the native tongue of either Lluis or Kartashov.

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PostPosted: Nov 23, 2007 07:22    Post subject: Re: Allanite-(La)?  

John,

Mr. Kartashov says on the Mindat's topic that by his analysis. "the REE2O3 of the Spanish Allanites-(La) arrive just to the 1-2 wt% and real allanites begin from 6-7 wt. % of REE2O3" but in the Record's article mentioned by Lluis, as well as yourself, authors found a 9-22% REE2O3 on the "BLACK" Allanites-(La) from Burguillos del Cerro.

As in Burguillos the "GREEN" Epidote is also a frequent mineral, Lluis has reasonable doubts about the mineral samples analyzed by Mr. Kartashov.

For sure I agree with you that the use of words like "idiocy" and "ridiculous" is unnecessary.

Jordi
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lluis




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PostPosted: Nov 23, 2007 12:54    Post subject: Re: Allanite-(La)?  

Dear Mr. Sampson White/ List

I am not the poster of the photos on Mindat, but that is not an important thing...
The photo commentary posted by Mr. Kartashov corresponds to a photo from Mr. Fabre, and it is, between others, on the Allanite-(La) Mindat's gallery.

I would like to clarify something that probably I expressed badly due to my poor English.

If the material were inclusions inside an epidote crystal, I would agree with Mr. Kartashov.

But, the material analyzed by Mr. Del Tánago and Mr. Sainz de Baranda, named in the paper “La rich allanite” because at that time allanite-(La) was not an IMA approved species, are not inclusions in a normal epidote. They are crystals of an allanite (REE oxides ranging from 9 to 22%; so as per IMA an allanite, not an allanite-(Ca) or epidote). The distribution of La varies inside the crystals, but the total REE oxides are high enough for the entire crystal to be allanite.

-The material is pitch black, not green as Mr. Kartashov says

-There is also epidote in Burguillos del Cerro, which is green. So perhaps, Mr. Kartashov has material that is epidote.

-Considering that in the analysis done by Mr. Del Tánago and Mr. Sainz de Baranda in "epidote" from Burguillos del Cerro shows no REE oxides, I doubt that the analysis performed by Mr. Kartashov was even related to material from Burguillos.

I feel not to be a combatant. I have no dog in this quarrel :-)
But for the sake of clarity in the mineralogical community, I thought that I should post this clarification. Evidently, Mr. Del Tánago and Mr. Sainz de Baranda are better qualified than I to defend their paper, but in their absence, I dared to do this.

With best wishes

Lluís
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PostPosted: Nov 24, 2007 05:32    Post subject: Re: Allanite-(La)?  

Given the much better description of the crystals by Iluis of those analysed by del Tanago and de Baranda, it seems quite clear that the locality does produce crystals that are entirely allanite-(La) and not just epidote with micro zones of allanite-(La) within them. I don't see how this characterization can be challenged by Mr. Kartashov and so perhaps the issue can be considered resolved. Let us hope so.
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PostPosted: Nov 24, 2007 14:16    Post subject: Re: Allanite-(La)?  

Dear Mr. Sampson-White/List

Thanks a lot for your answer.
Was for that that I could not understand why the pieces were challenged.
Perhaps it was a problem of language barrier

With best wishes for a nice week-end.

LLuís
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PostPosted: Aug 14, 2015 02:56    Post subject: Re: Allanite-(La)?  

This in a very old topic and sadly I sould say that the end is not a happy one ;-)

The most recent and careful studies proves that the Nueva Vizcaya Allanite crystals are zoned. Some zonation is La>Ce and some other zonation is Ce>La
So it seems that Allanite-(La) is not the most proper name for these samples. The best name could be "Allanite (Group)" or "Allanite-(La)/REE-rich epidote" considering that as Dr. José González del Tánago noted, in some crystals the REE content was even insufficient for Allanite...

For more info you can read Allanite-(La) in Mindat
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