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PhotosSogdianite?

7th Jul 2011 16:09 BSTStefan Koch Expert

0087787001310050620.jpg
Hello,


I need your help again. I own this specimen labeled as "Sogdianite from Tsumeb, Namibia". Additional informations on the label are: "achieved 1983 in Kapstadt/Capetown". There is also a small label glued on the specimen telling the same...


The problem is, Sogdianite is not listed for Tsumeb nor for Southern Africa. So I guess that this might be Sugilite from the Kalahari manganese fields. Is it possible to clear this up without making an analysis?


Specimen size is 6,5 x 5,5 cm.





Thanks for your help!

Stefan

7th Jul 2011 17:58 BSTRoger Lang Manager

Stefan,

this one looks a LOT like sugilite,

if you want me to make an xrd bring me a small portion for powder diffrac or leave me the specimen and we can test our new XRD. But after mindat conference and my holidays

cheers

Roger

8th Jul 2011 08:46 BSTStefan Koch Expert

Thanks Roger,


I'll bring it with me next time we meet!


:)

Stefan

8th Jul 2011 10:05 BSTPavel Kartashov Manager

I am suppose, that wrong identification of this sugilite (100% without any doubts) as "sogdianite" was made exactly by PXRD. Both minerals are isostructural and form series of solid solutions. BUT sugilite don't contain any Zr.;)

8th Jul 2011 12:50 BSTStefan Koch Expert

Thank you Pavel!


Does anybody have an idea about the possible find spot? Is my assumption correct that this is not a Tsumeb specimen? And that it might be most likely from the Kalahari manganese fields?

8th Jul 2011 12:56 BSTLefteris Rantos Manager

The locality is definitely wrong, it's from the Kalahari Mn Field.


As to its identity, the obvious answer is Sugilite. However Sugilite and Sogdianite ave very closely related species, so a detailed analysis might reveal a surprise here.


However it's much more likely that it's a mis-identified Sugilite (as Pavel explained), or - even worse - a "mistake" by some dealer who expected to sell it at a much higher price as Sogdianite...


Lefteris.

8th Jul 2011 13:46 BSTReiner Mielke Expert

While we are on this subject the description in Mindat is inadequate. The original description included : "Color beautiful violet (like kunzite), Cleavage {0001} perfect". Could someone please add this to the data base. The cleavage information is particularly useful in this case because I see no cleavage in this specimen.

8th Jul 2011 15:07 BSTRuth Raubenheimer

This is definitly Sugilite from the Kalahari Manganese fields - I live 200 km from the area and have similar specimens myself.

8th Jul 2011 16:48 BSTRoger Lang Manager

Pavel Kartashov Wrote:

-------------------------------------------------------

> I am suppose, that wrong identification of this

> sugilite (100% without any doubts) as "sogdianite"

> was made exactly by PXRD. Both minerals are

> isostructural and form series of solid solutions.

> BUT sugilite don't contain any Zr.;)


Of course you´re right Pavel,

so i will put it also in the XRF with our semiquant scan to check for Zr if Stefan wants to be 100% sure. But i also think an analysis is not necessary in this case. And yes, Kalahari Mn Field, i agree with the others,

cheers

Roger

21st Sep 2012 13:35 BSTgarry shaw

Hi i hope that this may help I bought a slice of SOGDIANITE back in 1968 i still have it, it is approximately 150 mm x 100mm x12mmthick it is highly polished on one side and natural on the other it is very deep violet/purple no other colours and is very waxy in texture on unpolished side.I bought this off a dealer in New Zealand.I now reside in Melbourne Australia and I am the President Of the Waverley Gem Club here.i have shown this peice to many dealers here and all say that they have never seen such a beautiful stone .when i say it is Sogdianite all but one have never heard of it and try to tell me that it is Sugilite.But i disagree with them.Also I can not find any where on the net where it is for sale so i have no idea of its value.but do know it is extremely rare.now any body reading this if you send me an email i will photo it and send a pic of both sides to you thanks Garry Shaw

21st Sep 2012 19:44 BSTUwe Kolitsch Manager

"But i disagree with them."

Why?

21st Nov 2016 11:25 GMTReiner Mielke Expert

So Roger what did the analysis show?

14th Jan 2017 23:35 GMTEmil Box

An old sample: Sogdianite, Hotazel South Africa

Now gives a PXRD (JCPDS ?): sugilite with quartz, pargasite, (trikalsilite). Thanks to a gentle colleague.

A Zr verification probably would help.

Milo

15th Jan 2017 04:26 GMTBruce Cairncross Expert

Roger,


You asked which mine your sugilite specimen comes from. Volumetrically, most Kalahari manganese field sugilite came from and still comes from the Wessels mine. In fact, in November 1999 Wessels mine auctioned 3,000 kg of sugilite. However, small amounts are periodically collected from N'Chwaning II and III mines. The latter produced unusual fibrous, hairlike sugilite a few years ago. But I would suggest your specimen most likely comes from Wessels mine.


Regards,

Bruce
 
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