Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Mineralogical Magazine Don't get GSW? Talk to your librarian.
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Mineralogical Magazine; October 2007; v. 71; no. 5; p. 579-585; DOI: 10.1180/minmag.2007.071.5.579
© 2007 Mineralogical Society of Great Britain and Ireland
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Guastoni, A.
Right arrow Articles by Vignola, P.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Mn-rich graftonite, ferrisicklerite, stanekite and Mn-rich vivianite in a granitic pegmatite at Soè Valley, central Alps, Italy

A. Guastoni1,2, F. Nestola1,3,*, G. Mazzoleni4 and P. Vignola5

1 Dipartimento di Geoscienze, Università degli Studi di Padova, Via Giotto 1, I-35137 Padova, Italy
2 Centro di Ateneo per i Musei, Università di Padova, Via Orto Botanico 15, I-35122 Padova, Italy
3 Istituto di Geoscienze e Georisorse, CNR Sezione di Padova, Via Giotto 1, I-35137 Padova, Italy
4 Stazione Valchiavenna per lo Studio dell’Ambiente Alpino, Via dei Cappuccini, I-23022 Chiavenna, Italy
5 CNR-Istituto per la dinamica dei processi ambientali, Via Mario Bianco 9, I-20131 Milano, Italy

* E-mail: fabrizio.nestola{at}unipd.it

Mn-rich graftonite, (Ca,Mn2+)(Fe2+,Mn2+)2(PO4)2, ferrisicklerite, Li1–x(Fe3+,Mn2+)PO4, manganoan apatite, (Ca,Mn2+,Fe2+Mg)(PO4)3Cl, stanekite, Fe3+Mn2+O(PO4) and Mn-rich vivianite, (Fe2+)3(PO4)2·8H2O, occurring in a granitic pegmatite at Soè Valley (central Alps, Italy) were characterized by powder and single-crystal X-ray diffraction (XRD) and electron microprobe analyses. Geochemically, the Mn-rich graftonite phases are poorly evolved Fe/Mn-phosphates of rare-earth elements-lithium (REE-Li) granitic pegmatites. The assemblage Mn-rich graftonite + ferrisicklerite + stanekite has rarely been documented in pegmatites. In the Soè Valley pegmatite, ferrisicklerite forms exsolution lamellae with Mn-rich graftonite associated with manganoan apatite and stanekite. Graftonite is associated with Mn-rich vivianite. Powder and single-crystal XRD data indicate that the unit-cell volume of graftonite increases as a function of Mn2+ content. Stanekite shows a distinctly smaller unit-cell volume with respect to previously reported stanekites, probably due to reduced Mn2+. Vivianite with significant Mn2+ has a unit-cell volume similar to nearly Mn-free vivianite. The formation of Mn-rich graftonite and manganoan apatite is related to destabilization of Mn-rich almandine and biotite during pegmatite formation. Ferrisicklerite forms exsolution lamellae along the 010 cleavage planes of Mn-rich graftonite, whereas stanekite forms by alteration of ferrisicklerite and Mn-rich vivianite due to circulation of late-stage hydrothermal fluids.

KEYWORDS: central Alps, Italy, Soè Valley, pegmatite, X-ray diffraction, microprobe, phosphates






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2008 by Mineralogical Society of Great Britain and Ireland