Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Di Muro, A. Articles by Principe, C. Search for Related Content GeoRef GeoRef Citation

Complex colour and chemical zoning of sodalite-group phases in a haüynophyre lava from Mt. Vulture, Italy

¹ Laboratoire de Physique et Chimie des Systèmes Volcaniques, IPGP-Paris VI, Case Courrier 109, Place Jussieu 4, Paris Cedex 05, France
² Dipartimento di Scienze della Terra, Universitá di Pisa, Via S. Maria 53, 56126 Pisa, Italy
³ Istituto di Geoscienze e Georisorse-CNR, Via G. Moruzzi 1, 56124 Pisa, Italy

^* E-mail: dimuro{at}ipgp.jussieu.fr

The haüynophyre emitted from a parasitic vent of the Vulture stratovolcano is a S- and Cl-rich, leucite-melilite-bearing lava flow containing an unusually large amount of sodalite-group minerals (>23 vol.%). Mineralogical and chemical study of phenocrysts has led to the identification of black haüynes, blue lazurites and of Cl-rich white or black noseans. X-ray diffraction (XRD) study confirms the occurrence of nosean having a low symmetry (P23). Raman spectra and XRD data show that S is fully oxidized to SO₄ in black haü ynes and in white noseans, while it is partly reduced to form S₃^– groups in blue lazurites, which also contain H₂O molecules. Structural and chemical data strongly question the validity of the Hogarth and Griffin (1976) method widely used to resolve the ratio S⁶⁺/S^2– in sodalite-group phases from EMPA data. Among euhedral phenocrysts, large lazurites are only faintly zoned. All other phases show variable core-rim chemical zoning and many phenocrysts are partially resorbed and/or colour-zoned. Black haüynes have highly variable S/Cl and slightly lower SiO₂/Al₂O₃ ratios, larger Fe_TOT contents and more compatible trace elements than lazurites. Thin opaque noseansodalite rims surrounding all crystals are interpreted as a result of rapid crystallization driven by exsolution of a S-scavenging fluid phase. We suggest that the extreme complexity of the mineralogical assemblage reflects variable a_SiO2 and a_H2O of the silicate melts.

KEYWORDS: haüyne, nosean, lazurite, Raman spectrometry, Mt. Vulture, Italy

This article has been cited by other articles:

				P. Ballirano and A. Maras Mineralogical characterization of the blue pigment of Michelangelo's fresco "The Last Judgment" American Mineralogist, July 1, 2006; 91(7): 997 - 1005. [Abstract] [Full Text] [PDF]

				P. BALLIRANO and A. MARAS Crystal chemical and structural characterization of an unusual CO3-bearing sodalite-group mineral European Journal of Mineralogy, December 1, 2005; 17(6): 805 - 812. [Abstract] [Full Text] [PDF]