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[jfc035]

I'm trying to figure out where this chalcopyrite on pale green fluorite comes from. The chalcopyrite disphenoids are up to 2 cm and the overall specimen is 10cm. it is associated with white rhombs of dolomite/calcite (?) casted on some faces of the chalcopyrite and a bit of black sphalerite (looks epitaxial with chalcopyrite). The fluorite has an octahedral habit and is recrystallized on the top face. there is no hint of purple/pink.

the specimen comes from an old French collection and was likely acquired before the 80s. The collection was overall well referenced. The specimen comes with a label indicating a French origin: Tarn dept. Yet, French collectors have never seen anything that big from Le Burc or Montroc.

Alternative provenances include:

Peru, Huanzala? Jaroslav Hyrsl and Jack Crowley say "why not" but have not seen anything like this.
Cornwall? yet some Cornish specialists have discarded this possibility.
Naica, Mexico was also evoked but I didn't find any similar chalcopyrite on fluorite.

Thanks for your help.
Merry Xmas

[Jordi Fabre]

Most probably Mont-Roc

[jfc035]

Thanks Jordi. I've also written to Alain yesterday and await his feedback.
Note however that there is no sphalerite nor dolomite at Mont-roc, in contrast to this specimen.

[makokerowill]

Good afternoon !
Your piece could have come from the Le Burg Mine (Le Burc mine), Alban - Le Fraysse area, Tarn, Occitanie, France. It complies with the paragenetic details and among its chalcopyrite, a friend has a piece with biesphenoids. It was the last mine of Fluorite to close in France in 2006.
Greetings and merry christmas.

[alfredo]

Although perhaps no sphalerite has been reported in Mont-Roc, I think that considering the presence of the commonly associated minerals pyrite, chalcopyrite, fluorite, barite, etc, the total absence of sphalerite is unlikely. It might be unobtrusive but, if someone were to hunt for it, they'd probably find some.

[ian jones]

Certainly not Cornish.

[jfc035]

Thanks for the current tips, but the question is still open...
At the moment the French say it cannot be French, the Peruvian experts say they're dubious about a Peruvian origin... only the Cornish are sure it's not Cornish -))
any additional tips will be appreciated

[alfredo]

"At the moment the French say it cannot be French,"

I do not see this anywhere. The label says France, and Jordi and Makekerowill think it could be France, so why not? In the absence of any strong claims to a different locality, I would keep the locality which is on the label.

[Peter Megaw]

Por mi parte...no es de Mexico

[jfc035]

[Riccardo Modanesi]

HI to everybody!
As a gemmologist I can say we NEVER certify the origin of a stone. Moreover, the biggest majority of gemmologists know what I think of a certification of stone origin: I mean, it's much more astonishing a diamond coming from the Formula One Ring Monza than a diamond coming from South Africa! Ok, it's a more information for a collector, but... I have also stones of "unknown origin".
Greetings from Italy by Riccardo.

[James Catmur]

You have been asking different people on many different platforms - which one do you want us to use?

I do have an opinion but it it totally hors-piste

[jfc035]

Hi James
I'm trying to decipher where such specimen comes from. I believe that the combination is distinctive enough to allocate it, hopefully someone has seen something like that before (?)
Any educated guess is welcome (on this forum!). What is your hors-piste idea?
thanks, jf