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As-rich apatite from Mt. Calvario; characterization by micro-Raman spectroscopy

Antonio Gianfagna, Simona Mazziotti-Tagliani, Alessandro Croce, Mario Allegrina and Caterina Rinaudo
As-rich apatite from Mt. Calvario; characterization by micro-Raman spectroscopy
The Canadian Mineralogist (October 2014) 52 (5): 799-808


In order to investigate content and localization of arsenic in natural fluorapatite, a micro-Raman spectroscopic study was carried out on As-rich fluorapatite crystals from the volcanic region of Mt. Calvario (Mount Etna, Italy). The crystals, from both the unaltered lavas and the metasomatized rocks, show a pure fluorapatite composition in the core, but an arsenic content of up to 15 wt.% As (sub 2) O (sub 5) in the rim of the crystals from the altered lavas. [AsO (sub 4) ] (super 3-) <--> [PO (sub 4) ] (super 3-) substitutions are proposed on the basis of chemical analysis performed with Electron Microprobe (EMP), Scanning Electron Microscopy (SEM-EDS), and Raman spectroscopy. Micro-Raman investigations carried out on the same crystals studied by EMP show a large band, anomalous for fluorapatite, near 860 cm (super -1) , where chemical microanalyses revealed high contents of As (sub 2) O (sub 5.) The Raman broad band near 860 cm (super -1) is produced by the vibrational modes of [AsO (sub 4) ] (super 3-) tetrahedra. No evidence of arsenate phase crystallization was found, therefore it is proposed that [AsO (sub 4) ] (super 3-) groups substitute for [PO (sub 4) ] (super 3-) groups in the apatite structure. Through mu -Raman spectroscopy, it has been possible to relate the iron content revealed by chemical analysis to magnetite in the fluorapatite from the unaltered lava, and to hematite inclusions in the inner core of the fluorapatite from metasomatized areas.

ISSN: 0008-4476
EISSN: 1499-1276
Coden: CAMIA6
Serial Title: The Canadian Mineralogist
Serial Volume: 52
Serial Issue: 5
Title: As-rich apatite from Mt. Calvario; characterization by micro-Raman spectroscopy
Affiliation: Sapienza Universita di Roma, Dipartimento di Scienze della Terra, Rome, Italy
Pages: 799-808
Published: 201410
Text Language: English
Publisher: Mineralogical Association of Canada, Ottawa, ON, Canada
References: 37
Accession Number: 2015-061905
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N37°45'00" - N37°45'00", E15°01'00" - E15°01'00"
Secondary Affiliation: Universita del Piemonte Orientale "Amedeo Avogadro", ITA, Italy
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Association of Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201527
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