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Wiluite from Ariccia, Latium (Italy). Occurrence and crystal structure (Articolo in rivista)

Type

Prodotto della ricerca (Classe)
Articolo in rivista (Classe)

Label

Wiluite from Ariccia, Latium (Italy). Occurrence and crystal structure (Articolo in rivista) (literal)

Anno

2005-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.2113/gscanmin.43.5.1457 (literal)

Alternative label

Bellatreccia F.; Camara F.; Ottolini L.; Della Ventura G.; Cibin G.; Mottana A. (2005)
Wiluite from Ariccia, Latium (Italy). Occurrence and crystal structure
in Canadian mineralogist; Mineralogical Association of Canada, Ottawa (Canada)
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

Bellatreccia F.; Camara F.; Ottolini L.; Della Ventura G.; Cibin G.; Mottana A. (literal)

Pagina inizio

1457 (literal)

Pagina fine

1468 (literal)

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43 (literal)

Rivista

Canadian mineralogist (Rivista)

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n.6 (literal)

Note

ISI Web of Science (WOS) (literal)

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Bellatreccia F. 1)2), Camara F. 3), Ottolini L. 3), Della Ventura G. 2), Cibin G. 2), Mottana A. 2). 1) Univ Roma La Sapienza, Dipartimento Sci Terra, I-00185 Rome, Italy; 2) Univ Roma Tre, Dipartimento Sci Geol, I-00146 Rome, Italy; 3) CNR, Ist Geosci & Georisorse, I-27100 Pavia, Italy; (literal)

Titolo

Wiluite from Ariccia, Latium (Italy). Occurrence and crystal structure (literal)

Abstract

We report a new occurrence of the rare mineral wiluite, the B-rich equivalent of vesuvianite, from Ariccia, Alban Hills volcano, Rome, Italy. The specimen studied was found in the collection of the Museum of Mineralogy of the University of Rome (label MMUR22496/482). Wiluite from Ariccia was sampled at the Parco Chigi quarry, within the phreatomagmatic unit emitted by the Albano maar known locally as \"Peperino di Marino\". It occurs as dark brown to black euhedral, well-formed prismatic crystals, up to 1.0 cm in length and 0.5 cm across. Optical observations show a weak pleochroism and an imperfect extinction. The mineral is uniaxial (+) with omega 1.722(2) and epsilon 1.727(2). It is tetragonal P4/nnc, a 15.716(2), c 11.704(2) angstrom, V 2890.8(7) angstrom(3). The crystal-chemical formula, obtained by combining EMP, SIMS and XREF data and calculated on the basis of 18 Si atoms, is: (x)(Ca18.72Mg0.15Sr0.02La0.05Ce0.04Nd0.01) (y(1))(Fe0.363+Mg0.26Ti0.27Mn0.11) (y(2))(Al3.67Fe0.193+Mg0.14) (y(3))(Al3.29Fe1.363+Mg3.35) (T(1))(B-2.18 Al0.02Be0.02H0.47 (1.31)) (T(2))(B0.68H0.32) (Si18O68)-Si-Z (O(11))(F1.21O6.79) ([O(10)+O(12)]) O-2.68. The micro OH-stretching FTIR spectrum consists of a defined triplet of broad bands at 3639, 3573 and 3488 cm(-1), respectively, and a very broad, composite absorption at 3300 cm(-1). All bands are strongly polarized, with maximum absorption for E // c and minimum absorption for E perpendicular to c. The integrated molar absorption coefficient for wiluite is epsilon(1), = 90.000 +/- 1500 1 mol(-1) cm(-2). In the 1600-1100 cm-1 region, absorptions due to both ([1])B3-0 and B-[4]-O bonds are observed. The Mg and Al K-edge X-ray-absorption spectra are consistent with the presence of two octahedral coordination sites for both atoms, as determined by XREF, with the addition of a third, highly unusual, five-fold pyramidal site for the divalent cation. (literal)

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