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Claraite from
Les Ferreres mine, Rocabruna, Camprodon, Ripollès, Girona (Gerona), Catalonia, Spain

Locality type:Mine
Classification
Species:Claraite
Formula:(Cu,Zn)15(CO3)4(AsO4)2(SO4)(OH)14·7H2O
Formation:Secondary
Comments:It is one of the most interesting species of the site and the first find in Catalonia. In the rest of the Iberian Peninsula it has only been found in the "La Amorosa" mine, Villahermosa del Río, Castellon (Cócera et al., 2010). The type locality is the “Clara” mine in Oberwolfach (Baden-Würtenberg , Germany) and characterized as hydrated copper and zinc hydroxylcarbonate (Walenta and Dunn, 1982). The structure has not yet been solved and only crystallographic constants are known (Walenta, 1999). According to Kolitsch, in an still unpublished study, the original formula is incorrect and should be amended, stating at least the arsenate anion (AsO4)-3 as arsenic appears to be almost always present. In addition, it is relatively common the presence of sulphur as sulfate anion (SO4)-2.
It appears as rosettes, divergent groups and spherulitic aggregates up to 1 mm, which can form druses up to a few squared centimeters, and also in more or less crystalline crusts. Color is intense sky blue in rosettes and crystal groups, and pale sky blue to bluish white in crusts. Individual crystals have tabular habit, often with hexagonal outline (claraite is triclinic pseudohexagonal) and are up to 0.4 mm.
It appears on dolomia matrix or filling fissures of baryte or dolomite, close to chalcopyrite and altered fahlore. It is often found associated to theisite, azurite (this mineral sometimes grows on claraite), aragonite and tyrolite.
Claraite from the Les Ferreras mine has been analyzed by SEM-EDS and confirmed by XRD. There is arsenic in all samples characterized, and in some of them there is also a low sulfur content, such as with claraite from Villahermosa del Río and from the Brixlegg-Schwaz (Tyrol, Austria) a mining area studied by Schnorrer (1994), Kolitsch (2007-2010) and Hepp & Hajek (2008). Our results reinforce the idea that the formula should be modified, stating at least the arsenate anion. Perhaps the formula should be written as that of tyrolite, presented later.
In the case of claraite from Rocabruna, the average relationship Zn :Cu is approximately 1:4,5. The empirical formula is approximately:
Cu,Zn)~10[(OH)~11|(SO4)0-0.5|(AsO4)0.3-1.5|(CO3)2.5-3] +nH2O


Habit:Tabular pseudohexagonal crystals. Crusts.
Colour:Blue
Quality for species:Excellent - world class for species or very significant. (!!)
Abundance at site:Common
Confirmation
Validity:Believed Valid
References
References:Garrido, J.L., Rosell, J., Viñals, J., Bártulos, V., Mingueza, P., Ortiz, X and Vinyoles, J. (2013): "Mineralogy of Les Ferreres mine, Rocabruna, Camprodon, Catalonia". Mineral Up, Vol.3, Nr.4, 6-23.

Rosell, J., Garrido, J.L., Viñals, J., Bártulos, V., Vinyoles, J., Ortiz, X., Mingueza, P., Masons, G., Bobi, F. (2014): Rocabruna i el seu entorn. La mina de les Ferreres. Edited by the authors and Grup Mineralògic Català. 128 pages (with the mineralogy chapters in Spanish and English).
Associated Minerals Based on Photo Data:
Theisite5 photos of Claraite associated with Theisite at this locality.
Azurite4 photos of Claraite associated with Azurite at this locality.
Data
Mineral Data:Click here to view Claraite data
Locality Data:Click here to view Les Ferreres mine, Rocabruna, Camprodon, Ripollès, Girona (Gerona), Catalonia, Spain
Photo GalleryView Gallery (2 photos)
 
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