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Improving Mindat.orgOlmiite versus Poldervaartite
2nd Aug 2008 11:48 UTCMario Pauwels
I was looking thru the Poldervaartite gallery and I think there are some Olmiite specimens between the Poldervaartites.
Both pictures: 110387 & 8817 are probable Olmiite instead of Poldervaartite.
One picture: 122293 should be changed in Olmiite / Poldervaartite / Calcite.
Some other Poldervaartite pictures look also a bit "suspicious", but they are more difficult to examine on the pictures.
Regards,
Mario Pauwels
2nd Aug 2008 15:07 UTCGail Spann Manager
Now I have to go back and take a guess at what is what as I have them in all different spectrums of colour from chalky white to deep russet red.
After learning to spell and say Poldervaartite, it isn't half as much fun to say Olmiite. (:P)
Cheers.
26th Apr 2021 02:21 UTC曹啸天 (XiaoTian (Joseph) Cao)
7th Aug 2008 20:55 UTCAnatoly Kasatkin
15 specimens from N'Chwaning II and Wessels and ALL of them independently
of habit, colour etc. - all turned out to be olmiites with very clear dominance of Mn over Ca in the second position.
Now I have a strong suggestion that all the poldervaartites that filled the mineral market (including all pictured on mindat) are in fact olmiites.
It needs to be said that even the analysis given by the authors of poldervaartite for the homogenous grain of holotype material showed dominance of Mn over Ca.
Only one crystal of holotype poldervaartite used to make a crystal structure showed,
according to authors, slight dominance of Ca over Mn. So actually it seems that
even the holotype poldervaartite is, in fact, the zonal growths of poldervaartite/olmiite.
In our analyses we unfortunately never found traces of such zonal growths, never even a ratio
close to 50/50, everytime Mn was strongly dominant. One thing is evident: it is impossible to clearly ID the species basing on visual examination.
I discussed this problem several times with Renato Pagano (co-author of Olmiite), also with Dr.Bruce Cairncross etc. Renato said that more investigations are needed.
So far, I suggest poldervaartite being EXTREMELY rare species. I certainly don't have it in my systematic collection. Since SA mines are very prolific we can only hope that new find of Ca-rich material will be made, but so far, very tough WDS-work and very BIG luck are necessary to find points of the true poldervaartite!
Warmest,
Anatoly
7th Aug 2008 21:34 UTCUwe Kolitsch Manager
23rd Sep 2008 11:18 UTCFranz Neuhold
I recently had a visibly heavily zoned crystal of Olmiite-Poldervaartite (N'Chwaning II) under the SEM. The EDS results were ranging from a - most likely - typical Olmiite (CaO:MnO 1,35) to nearly Mn-free Poldervaartite (CaO:MnO 200!) in the outer rims. The crystal faces and fractured areas are both free of any overgrowths.
But as Anatoly already said: naming it Olmiite or Poldervaartite should not be done basing on visual examination!
Regards,
Franz
23rd Sep 2008 13:07 UTCGail Spann Manager
23rd Sep 2008 13:13 UTCJolyon Ralph Founder
http://www.mindat.org/min-38781.html
Perhaps we should move all Olmeiite/Poldervaartite photos to this unless they've been confirmed by EDS or similar.
Jolyon
26th Feb 2009 14:46 UTCPeter Hargis
26th Feb 2009 15:51 UTCMarco E. Ciriotti Manager
""Remarks:
Olmiite is the Mn-dominant analogue of poldervaartite, Ca(Ca,Mn)(SiO3OH)(OH), with which it forms a
series. A fair amount of “poldervaartite” have reached the market in the recent years, but most samples turned
out to be olmiite. Genuine poldervaartite specimens, thus, must be regarded as extremely rare and seem
to be limited to the original finding in the 1980s at the Wessels mine, Cape Province, Republic of South
Africa.""
26th Feb 2009 17:10 UTCAnatoly Kasatkin
Also I can note that in Franz Neuhold's case it can be probably a first reliable find of Poldervaartite from N'Chwaning II.
Warmest,
Anatoly
3rd Apr 2009 23:44 UTCMario Pauwels
What is happening with the Poldervaartite gallery now ?
It turned out that all recently discovered Poldervaartites are in fact Olmiites, but many of these new specimens are still posted and displayed with picture in the Poldervaartite gallery.
Regards,
Mario Pauwels
29th Nov 2012 18:41 UTCPierre Rondelez
More than3 years later and not much has changed on Mindat concerning Poldervaartite/Olmiite.........
Strange to say the least.
Pierre
29th Nov 2012 19:59 UTCClosed Account 🌟
there are currently 9 photos in the poldervaartite gallery and 308 in the olmiite gallery. So I cannot really consent with your statement of " not much has changed". However I agree that some of the 9 poldervaartite photos might not be what they claim to be.
Branko
30th Nov 2012 08:07 UTCPierre Rondelez
Yesterday morning, there were 13 poldervaartites in the gallery, by evening 8 remained, the rest had been removed to the olmiite gallery.
So yes, some changes were made yesterday...........
Most of the ones remaining will remain there I am afraid, just look at who posted them on the claim that they came from old collections, which really means nothing else than before the existence of olmiite (and the wrong id. of poldervaartite) was known.
Pierre
30th Nov 2012 10:26 UTCMario Pauwels
Since I started this tread more then four years ago, a lot of the mislabeled "Poldervaartite's" are moved to the Olmiite gallery. This was a very slow proces, and during these four years there were still new Olmiite's pictures posted (and accepted !) in the Poldervaartite gallery, while it was clear since Anatoly's statement that it was wrong to accept them as Poldervaartite.
Finaly everything looks solved now after your recent complains Pierre(tu). So thanks for bringing this topic back under attention.
I also agree with you that from the 7 pictures who remain at this moment in the Poldervaartite, that most specimens look very suspicious and are most likely Olmiites.
Best regards,
Mario Pauwels
30th Nov 2012 10:52 UTCPierre Rondelez
Things seem to be moving now (at last), only 7 remaining today of which 2 are probables, the other 5 (amongst which the head photo) are very suspicious.
Cheers,
Pierre
30th Nov 2012 11:19 UTCClosed Account 🌟
From my experiences there are 2 "most likely", one is confirmed and 4 doubtful. Please be patient for just some more hours, and we will have a solution. I am working on it.
Branko
30th Nov 2012 16:29 UTCClosed Account 🌟
There are currently 3 specimens remaining in the poldervaartite photo gallery which are considered true IDs. I hope that no other, incorrectly identified photos are uploaded in the future, but if one slips through there is always the possibility of a note in this thread.
@Matio, Pierre
Thanks for bringing this up!
30th Nov 2012 17:25 UTCPierre Rondelez
Thanks for the good work,
Pierre
1st Dec 2012 09:47 UTCMario Pauwels
Anyway I am glad that everything is finally solved now. Thank you everyone for your response and also Branco for your 'action'.
Best regards,
Mario Pauwels
1st Dec 2012 10:10 UTCPierre Rondelez
I could not agree more.
Pierre
Mario Pauwels Wrote:
-------------------------------------------------------
> I was just wondered why it has taken more than
> four years to cleaning this mess up. I truly can
> not believe that a dealer could have that much
> influence to keep misidentified specimens in a
> certain gallery, or that I was not taking to
> seriously when I started this Olmiite versus
> Poldervaartite topic four years ago...
>
> Anyway I am glad that everything is finally solved
> now. Thank you everyone for your response and also
> Branco for your 'action'.
>
> Best regards,
> Mario Pauwels
1st Dec 2012 12:55 UTCReiner Mielke Expert
1st Dec 2012 13:58 UTCPierre Rondelez
That must surely be an error!
Pierre
26th Apr 2021 02:21 UTC曹啸天 (XiaoTian (Joseph) Cao)
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2024, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 19, 2024 11:42:05