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Spherocobaltite

Posted by Georges Favreau  
avatar Spherocobaltite
January 22, 2008 03:03PM
    
Hello,

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 letterssmiling smiley. 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.
Re: Spherocobaltite
January 22, 2008 04:11PM
    
Hello,

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.
avatar Re: Spherocobaltite
January 22, 2008 04:25PM
It's a real mess. We should probably remove all sphaerocobaltite photos that can't be proved by analysis.

Jolyon
avatar Re: Spherocobaltite
January 22, 2008 08:03PM
    
Hi,
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
avatar Re: Spherocobaltite
May 15, 2008 03:01PM
    
Dear all,

Before everyone forgets this topic winking smiley
(and this one [www.mindat.org])

Yesterday I opened the box with all the real ( winking smiley ) 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 winking smiley

Real Spherocobaltite?
Only optical... I think (shoot me) this is typical for Spherocobaltite:
[www.mindat.org]
(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
Re: Spherocobaltite
May 16, 2008 04:01PM
Hi,

I will post a photograph of verified Swiss spherocobaltite xx soon as well, if I can get a decent photograph...

Frank
avatar Re: Spherocobaltite
May 16, 2008 05:23PM
    
Hi,

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
Re: Spherocobaltite
June 14, 2008 09:50AM
Hi,

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
Re: Spherocobaltite
June 14, 2008 04:54PM
    
Message sent on 169967.
Re: Spherocobaltite
June 14, 2008 05:06PM
    
Have started to send inquiries on all remaining questionable photos (have deleted one (poor) questionable photo).
avatar Re: Spherocobaltite
June 14, 2008 05:57PM
    
thanks Uwe
Re: Spherocobaltite
August 01, 2008 06:19PM
I have a follow-up question about sphaerocobaltite--having found this thread on the Messageboard, last posted some months ago.

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
Re: Spherocobaltite
August 06, 2008 03:09PM
I have nothing to add on the current validity of "sphaerocobaltite" as a species. There certainly is a natural cobalt carbonate; perhaps the name confusion goes back to Dana 7th in which the nomenclature got muddied with "cobaltocalcite". Whatever it's called, this is one of my all time favorite minerals. I first saw a magnificent specimen of this in the museum of the Colorado School of Mines back in 1961, and lusted after a specimen ever since (:D.

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.
avatar Re: Spherocobaltite
May 08, 2012 01:50PM
    
Hi all,

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.
avatar Re: Spherocobaltite
May 08, 2012 08:28PM
Paul,
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.

Rock Currier
Crystals not pistols.
avatar Re: Spherocobaltite
May 08, 2012 09:41PM
    
Rock,

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.
Re: Spherocobaltite
May 08, 2012 10:57PM
I have analyzed many "pink" cobalt bearing carbonates.

None have risen to the level of true "spherocobaltite"

Don't even get me started on otavite.

Bart
Re: Spherocobaltite
May 09, 2012 11:25AM
Hello,

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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