Varenche Mine, Saint-Barthélemy, Nus, Aosta Valley, Italy
(Miniera di Varenche, Saint-Barthélemy, Nus, Valle d'Aosta, Italia)
Old Mn mine opened in jasper.
The metasedimentary rocks at Varenche probably form part of the Combin Unit, a composite nappe made up of calcschists, MORB-type metabasalts and metagabbros, serpentinites and pelagic (partly manganesiferous) metasediments, which were metamorphosed at greenschist facies conditions. The highly oxidized Mn-rich rocks consist mainly of varicolored spessartine-hematite quartzites and braunite- and spessartine-bearing rocks, with variable proportions of rhodochrosite, "crossite"-magnesioriebeckite, phlogopite, clinochlore, talc, Na-bearing pyroxene, rutile and barite, and uncommon minerals such as ardennite, arseniopleite, manganberzeliite, thortveitite.
References:
- Pagani, G. (1973): Località mineralogiche consigliate. Varanche - St. Barthelemy (Lignan - Aosta). Notiziario del Gruppo Mineralogico Lombardo, 4, 82-84.
- Baldelli C., Dal Piaz G.V. & Polino R. (1983): Le quarziti a manganese e cromo di Varenche-St. Barthélemy, una sequenza di copertura oceanica della falda piemontese. Ofioliti 8, 207-221. (in Italian)
- Pasero, M., Reinecke, T., Fransolet, A.-M. (1994): Crystal structure refinements and compositional control of Mn-Mg-Ca ardennites from the Belgian Ardennes, Greece and the Western Alps. Neues Jahrbuch für Mineralogie, Abhandlungen, 166, 137-167.
- Bonazzi P., Menchetti S., Reinecke T., 1996. Solid solution between piemontite and androsite-(La), a new mineral of the epidote group from Andros Island, Greece. American Mineralogist, 81, 735-742.
- Barresi, A.A., Kolitsch, U., Ciriotti, M.E., Ambrino, P., Bracco, R., Bonacina, E. (2005): La miniera di manganese di Varenche (Aosta, Italia nord-occidentale): ardennite, arseniopleite, manganberzeliite, pirofanite, sarkinite, thortveitite, nuovo As-Sc-analogo della metavariscite e altre specie. Micro (località), 2/2005, 81-122.
- Barresi, A.A., Kolitsch, U., Ciriotti, M.E., Ambrino, P., Bracco, R., Bonacina, E. (2007): Errata corrige: Varenche. Micro (località), 1/2007, 180-180.
- Barresi, A., Orlandi, P., Pasero, M. (2007): History of ardennite and the new mineral ardennite-(V). European Journal of Mineralogy, 19, 581-587.
- Piccoli, G.C., Maletto, G., Bosio, P., Lombardo, B. (2007): Minerali del Piemonte e della Valle d'Aosta. Associazione Amici del Museo "F. Eusebio" Alba, Ed., Alba (Cuneo) 607 pp.
Mineral List:73 entries listed. 69 valid minerals.
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