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Improving Mindat.orgSpherocobaltite
22nd Jan 2008 15:03 UTCGeorges Favreau Manager
I understand that keeping up an accurate list of pictures with so many contributors (and contributions) is far from easy, and I do not want to be the bad guy who always complains.
However, I found a topic on which some "maintenance" should be worth it.
It seems to me that many specimens in the spherocobaltite gallery should be questioned (maybe even REAL spherocobaltite in upper case letters:-). This is the same in mineral shows…
Here is a first list of specimens that more look like calcite or dolomite specimens containing some cobalt (I even do not want to say "cobalt-rich" as the Co contents may be a few % or even far less):
37140
39500
52296
86173
10658
100872
114258
67416
49678
29026
On a second list of specimens, the picture is not sufficient, but specimen checking can prove useful too:
88877
4754
34029
67412
112194
112196
Altogether this means 16 specimens out of the 25 presented in the gallery. On specimens of both lists, spherocobaltite may be present on the specimen, and I do not want to question that, but maybe on parts which are not seen on the pictures…
Now to help identify some specimens: calcites will be easily checked with dilute cold hydrochloric acid. Dolomite will eventually dissolve after longer exposure to acid. "Real" Spherocobaltite should not dissolve (maybe minor etching can be seen), even after a long time in acid. The mineral can be magnetic, but I do not know if it is still when not pure.
I will try to post shortly a picture of analytically verified specimen from the Bou Azzer district.
Georges.
22nd Jan 2008 16:11 UTCLefteris Rantos Expert
I absolutely agree, I had thought of this several times before, while browsing the Spherocobaltite gallery. I agree with Georges, concerning the following photos (some are obviously cobaltoan Calcites):
37140
39500
88877
52296
86173
10658
34029
67415
67416
100872
114258
49678
29026
For these two, I can't really tell:
4754
112194
Indeed it's a tough case concerning this mineral, and it's not always possible to tell without an analysis. But some specimens are either clearly NOT Spherocobaltite, or at least are NOT representative at all for the species, and leave serious doubts.
I've had the same problem some years earlier, with the 'Spherocobaltites' in my collection: Out of three specimens (all from the DR of the Congo), two showed efervescence in HCl, indicating Calcite.
And even one that looked like TYPICAL spherocobaltite! It looked exactly like photos 108152 or 27426 (bright pink spheroidal/stalactitic aggregates, with slightly paler interior, where broken), but dissolved like Calcite or Dolomite!
Lefteris.
22nd Jan 2008 16:25 UTCJolyon Ralph Founder
Jolyon
22nd Jan 2008 20:03 UTCAntonio Borrelli Expert
I have checked my specimen (photo #37140) and it is certainly dolomite.
Thanks Georges for pointing this out.
Now I'm looking for a real spherocobaltite!
Antonio
15th May 2008 16:01 UTCFrank de Wit Manager
Before everyone forgets this topic ;-)
(and this one http://www.mindat.org/forum.php?read,11,87351,87351#msg-87351)
Yesterday I opened the box with all the real ( ;-) ) Spherocobaltites I found in april at Oumlil and Filon-2 (Bou-Azzer). I agree with Jolyon. Delete all the pics... Better: let Georges pick all the pictures that can stay ;-)
Real Spherocobaltite?
Only optical... I think (shoot me) this is typical for Spherocobaltite:
http://www.mindat.org/photo-102673.html
(compare Le Cahier des Micromonteurs 2-2007 p.58 (2 pictures) and p.83 and Le Cahier des Micromonteurs 3-2001 p.80+99 and Lapis 7/8-2006 p.39+45)
Cheers! Frank
16th May 2008 17:01 UTCFrank Keutsch Expert
I will post a photograph of verified Swiss spherocobaltite xx soon as well, if I can get a decent photograph...
Frank
16th May 2008 18:23 UTCPaul De Bondt Manager
I pointed this out when I started the Cobalto-Adamite forum. This was also a mess.
Thanks Georges, you are right about this specie.
Spherocobaltiet crystals are VERY different from Co-Calcite or Dolomite.
As an avid Katanga collector I don't collect names on labels but mineral species. To avoid this problem, I let check all the doubtfull minerals by Dr. Deliens, and sometimes the common species to.
I check the pics and I wil give my feeling about Sphero.
Sincerely
Paul
14th Jun 2008 10:50 UTCHenri De Coen
On the yesterday uploaded gallery the same problem occur.
Picture 169967 is NOT spherocobaltite but more cobalto-dolomite or calcite.
Probably one of those but certainly NOT sphero.
Henri
14th Jun 2008 17:54 UTCUwe Kolitsch Manager
14th Jun 2008 18:06 UTCUwe Kolitsch Manager
14th Jun 2008 18:57 UTCPaul De Bondt Manager
1st Aug 2008 19:19 UTCPETER J MODRESKI
This came to my attention after I started to post a reply to a query on another online chat about minerals--the Rockhounds@drizzle.com, listserver. Is sphaerocobaltite confirmed to be a valid species? I see that the latest (2008) Glossary of Minerals simply says "Discredited", but gives no further information. Mindat, and the online IMA mineral species list (which I realize is not often updated), as well as other online sources, all do still list sphaerocobaltite as a species. Putting aside all those cases in which cobalt-bearing calcites have been incorrectly assumed to be sphaerocobalite, has the existence of the Co-dominant carbonate itself, been discredited?
Thank you--I'm curious to see what information people may have about this--
Pete Modreski
6th Aug 2008 16:09 UTCWilliam G. Lyon
The recent assertion in Min. Rec. 38(5), 396 (Bou Azzer issue) that sphaerocobaltite is magnetic enough at room temperature to be detected with a strong magnet sounds to me like a bunch of hooey. Cobalt carbonate is antiferromagnetic with a Neel temperature below the liquid nitrogen range. (See refs. below) There's some possibility that the mineral from this location either has magnetic inclusions. Otherwise, I would expect only a weak parasitic ferromagnetism from the slightly canted magnetic moments (i.e., Dzyaloshinsky effect) as in the other carbonates, siderite and rhodachrosite. These last two when pure are definitely not sufficiently magnetic to be picked up by a simple magnet.
Kalinkina, I. N. (1963) Magnetic heat capacity of antiferromagnetic
Co, Ni, Mn, and Fe carbonates: Journal of Experimental
and Theoretical Physics, 16, 1432-1438(. Translation of Zhurnal
eksperimental'roi i teoreticheski fiziki 43, 2028-2037,
1962.
Robie et al., 1984
Heat Capacities and Entropies of Rhodochrosite (MnCO3) and Siderite (FeCO3) between 5 and 600 K.
Am. Mineral. 69, 349-357.
Some simple rules of thumb to sort out cobaltoan calcite, cobaltoan dolomite, and sphaerocobaltite:
Cobaltoan calcites generally are a pale pink and the crystals run larger than for the dolomitic species. Cobaltoan dolomites can be a hot pink, and are most often available as drusy crusts of small crystals (< 1 mm). The difference in color saturation is due to the higher solubility of cobalt in dolomite on the Mg sites.
Sphaerocobaltite is a much darker, red raspberry color. Relatively little sphaerocobaltite is available commercially, and then only from those dealers who actually know their minerals well.
Lots of cobaltoan dolomite is mislabeled at rock shows, and virtually nothing you can say to one of these dealers will convince him that it is mislabeled.
8th May 2012 14:50 UTCPaul De Bondt Manager
Swinging this topic on again.
The Spherocobaltite page of Katanga is CLEANED UP, thanks to the concerned members.
I hope this helps.
Take care and best regards.
Paul.
8th May 2012 21:28 UTCRock Currier Expert
I admire the work you are doing. It takes a person with specialized knowledge to do it. By this time I am sure you realize that we need a lot of work done in this regard. When and if you finish with Katanga, be sure you let us know. We need to find a place to keep track of who did what and when in this kind of general image vetting.
8th May 2012 22:41 UTCPaul De Bondt Manager
Thank you for your encourragements.
The Katanga dioptase and baryte are almost done too.
Untill now, more than 100 images have been moved to the right localities and mineral names.
I hope this helps.
Take care and best regards.
Paul.
8th May 2012 23:57 UTCBart Cannon
None have risen to the level of true "spherocobaltite"
Don't even get me started on otavite.
Bart
9th May 2012 12:25 UTCGunnar Färber
I have analyzed many specimens from Katanga, all of them are just Co rich Calcite or Dolomite. The only confirmed ones are the newly find from Bou Azzer approx. 2 years ago. I have never test the old specimens from there. The real Spherocobaltite develop only in high grade massive Cobalt ore.
Gunnar
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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 18, 2024 02:03:06