Dear Dr. Brough,

the addressee is the Commission on New Minerals, Nomenclature and Classification (CNMNC) of IMA

http://nrmima.nrm.se//

Details for new minerals are found here:

http://nrmima.nrm.se//newminer.htm

Best regards

H.G.Dill

Thanks Harald,

Looking through their requirements it is apparent that in theory most of the required data could be acquired given access to sufficiently advanced equipment. Particularly fascinated by their comment;

"it is now possible to perform complete chemical and crystal-structure analyses on nanometric volumes, i.e., on the scale of a few Ångström units"

... which would presumably allow for extraction of a small portion from a thin section and analysis from that.

In practise though and without access to that equipment it would seem a dream for now. Nevertheless I will contact the addressee and see what comes of it.

Regards,

Chris

Dear Chris,

In case of further need, I recommend Uwe Kolisch (see address below) he is an expert on that matter and maybe you can embark on a cooperation with him.

I wish you much success.

Harald

Priv.-Doz. Dr. Uwe Kolitsch

Kurator der Mineralien- und Lagerstättensammlung

Mineralogisch-Petrographische Abt.

Naturhistorisches Museum

Burgring 7

A-1010 Wien, Austria

Tel +43-1-52177-274, Fax +43-1-52177-263

E-mail: [email protected]

Website: http://www.nhm-wien.ac.at/uwe_kolitsch

Many thanks

The IMA has published rules on naming a new mineral. On the IMA Commission on New Minerals, Nomenclature and Classification website there is a checklist (actually a form) that lays out what is requested to propose a new mineral for approval. There are also the guidelines that need to be followed. All can be found at: http://nrmima.nrm.se/

It should be noted that there are a lot of things asked for but not all information can always be obtained. What defines the mineral is a unique combination of its chemical formula and crystal structure. If these can be determined then you can submit it. From your description you indicate that "Ta" seems to be substituting for "Nb". This touches on knowing which element is dominant at which site. The IMA has a "50%" rule meaning that whichever element is more than 50% filling a site in the structure then that can determine a distinct species. If you need some help with putting together a proposal to the CNMNC I would be willing to help you with that. In the meantime if you wish to apply for a temporary IMA unnamed mineral number should you wish to persue publication, I can take the application and submit it to the relevant Subcommittee.

Dear Jeffrey de Fourestier, 

Thank you for the information and the help. 

We have inferred the substitution of Nb with Ta based on the zonation that is apparent within the mineral and analysis across that zonation. Though from memory I think Nb was always greater than Ta. Based on the 50% rule the mineral may therefore still be peterandresenite even with the high Ta concentrations, though of course we have no information yet on crystal structure. 

I would certainly need some help with putting together a proposal for CNMNC and appreciate your offer of help. Do you have an e-mail address I can contact you further on? Alternatively you can contact me on [email protected]

Kind regards,

Chris

Dear Sir,

I bbelieve that the mineral got approval: pyrochlore supergroup mineral approved by the CNMNC (IMA 2012-036).

In any case please do powder XRD, and EPMA for composition analyses for authentic information.

Best Regards,

G.Parthasarathy

Thanks for the suggestion G.Parthasarathy,

We are aware that fluorcalciomicrolite (IMA 2012-036) was approved in 2012 and though we have this mineral in thin section, the mineral it is associated with is still new to us.

We had wondered about the pyrochlore group for the mineral in question, and one mineral that was suggested was hydroxymanganopyrochlore. However, from the optical data we know that the mineral is not isometric (thereby ruling out pyrochlores, and specifically ruling out hydroxymanganopyrochlore). There is also no titanium, calcium, iron, sodium or REE observed which typically go with pyrochlore minerals. 

We have done a fully quantified analysis on the grains in question. We haven't yet undertaken a powder-XRD owing to very small sample volume.

Kind Regards,

Chris

Dear Chris,

XRD is essential for the characterization (single crystal and/or powder).

A first step could be microdiffraction. This can be done on the slice without any destruction or without removing some material. If the material is microcrystalline, the pattern can be quite good. If it is a single crystal you will get just a very few peaks (or possibly just a single one), but even this might help to establish or exclude a relation to a known mineral.

Kind regards,

Thomas

Many minerals associated with pyrochlore could be symplectite or alteration product. You need to be sure that the total of your microprobe analysis between 99-100, if the mineral is anhydrous, otherwise, it could be an alteration of pyrochlor

Thanks Sobhi, we have assumed that it is an alteration product after the fluorcalciomicrolite. But the analysis to date strongly suggests that it is hydrous with low total wt% values after standardisation of all the contained elements. The question remains as to the mineral designation whether or not it is an alteration product or not, as the chemical constituents and proportions don't easily fit known minerals apart from a possible analogue in peterandresenite.

The analogue is possible but we still need to be certain how much Ta can fit in Peterandresenite without significantly altering the crystal structure (or whether indeed Peterandresenite permits the inclusion of Ta as a solid-solution substitute for Nb).

Dear Christopher,  for crystallographic characterizataion,  without removing materials, you can use EBSD, electron backscatter diffraction. The experimental EBDS patterns are automatically indexed by comparison  with simulated patterns based on CIF ( Crystallographic Information Files. For more details you can write me:  [email protected]

kind regards

Gian Carlo Parodi