Hostname: page-component-78c5997874-ndw9j Total loading time: 0 Render date: 2024-11-10T11:11:18.180Z Has data issue: false hasContentIssue false
  • English
  • Français

Tazzoliite: a new mineral with a pyrochlore-related structure from the Euganei Hills, Padova, Italy

Published online by Cambridge University Press:  05 July 2018

F. Cámara ,
F. Nestola ,
L. Bindi ,
A. Guastoni ,
F. Zorzi ,
L. Peruzzo  and
D. Pedron
F. Cámara*
Affiliation:
Dipartimento di Scienze della Terra, Università di Torino, Via Valperga Caluso 35, I-10125 Torino, Italy
F. Nestola
Affiliation:
Dipartimento di Geoscienze, Università di Padova, Via Gradenigo 6, I-35131 Padova, Italy
L. Bindi
Affiliation:
Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, I-50121 Firenze, Italy
A. Guastoni
Affiliation:
Museo di Mineralogia, Università di Padova, Via Giotto 1, I-35122 Padova, Italy
F. Zorzi
Affiliation:
Dipartimento di Geoscienze, Università di Padova, Via Gradenigo 6, I-35131 Padova, Italy
L. Peruzzo
Affiliation:
C.N.R., Istituto di Geoscienze e Georisorse, Via Gradenigo 6, I-35131 Padova, Italy
D. Pedron
Affiliation:
Dipartimento di Scienze Chimiche, Università di Padova, Via Marzolo 1, I-35131 Padova, Italy
*
*E-mail: fernando.camaraartigas@unito.it
Get access Rights & Permissions [Opens in a new window]

Abstract

Tazzoliite, ideally Ba2CaSr0.5Na0.5Ti2Nb3SiO17[PO2(OH)2]0.5, is a new mineral (IMA 2011-018) from Monte delle Basse, Euganei Hills, Galzignano Terme, Padova, Italy. It occurs as lamellar pale orange crystals, which are typically a few m m thick and up to 0.4 mm long, closely associated with a diopsidic pyroxene and titanite. Tazzoliite is transparent. It has a white streak, a pearly lustre, is not fluorescent and has a hardness of 6 (Mohs' scale). The tenacity is brittle and the crystals have a perfect cleavage along {010}. The calculated density is 4.517 g cm–3. Tazzoliite is biaxial (–) with 2Vmeas of ~50º, it is not pleochroic and the average refractive index is 2.04. No twinning was observed. Electronmicroprobe analyses gave the following chemical formula: (Ba1.93Ca1.20Sr0.52Na0.25Fe0.102+)Σ4 (Nb2.88Ti2.05Ta0.07Zr0.01V0.015+)Σ5.02SiO17[(P0.13Si0.12S0.07)Σ0.32O0.66(OH)0.66][F0.09(OH)0.23]Σ0.32.

Tazzoliite is orthorhombic, space group Fmmm, with unit-cell parameters a = 7.4116(3), b = 20.0632(8), c = 21.4402(8) Å, V = 3188.2(2) Å3 and Z = 8. The crystal structure, obtained from single-crystal X-ray diffraction data, was refined to R1(F2) = 0.063. It consists of a framework of Nb(Ti) octahedra and BaO7 polyhedra sharing apexes or edges, and Si tetrahedra sharing apexes with Nb(Ti) octahedra and BaO7 polyhedra. The structure, which is related to the pyrochlore structure, contains three Nb(Ti) octahedra: two are Nb dominant and one is Ti dominant. Chains of A2O8 polyhedra [A2 being occupied by Sr(Ca, Fe)] extend along [100] and are surrounded by Nb octahedra. Channels formed by six Nb(Ti) octahedra and two tetrahedra, or four A1O8(OH) polyhedra (A1 being occupied by Ba), alternate along [100]. The channels are partially occupied by [PO2(OH)2] in two possible mutually exclusive positions, alternating with fully occupied A3O7 polyhedral pairs [A3 being occupied by Ca(Na)]. The seven strongest X-ray powder diffraction lines [d in Å (I/I0) (hkl)] are: 3.66 (60) (044), 3.16 (30) (153), 3.05 (100) (204), 2.98 (25) (240), 2.84 (50) (064), 1.85 (25) (400) and 1.82 (25) (268). Raman spectra of tazzoliite were collected in the range 150–3700 cm–1 and confirm the presence of OH groups. Tazzoliite is named in honour of Vittorio Tazzoli in recognition of his contributions to the fields of mineralogy and crystallography.

Keywords

tazzoliitenew mineralcrystal structurepyrochloreRaman spectroscopyEuganei hills
Type
Research Article
Information
Mineralogical Magazine , Volume 76 , Issue 4 , August 2012 , pp. 827 - 838
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Atencio, D., Andrade, M.B., Christy, A.G., Giere, R. and Kartashov, P.M. (2010) The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48, 673–698.CrossRefGoogle Scholar
Astolfi, F. and Colombara, F. (2003) La geologia dei Colli Euganei. Edizioni Canova. Treviso.Google Scholar
Balic Zunic, T., Petersen, O.V., Bernhardt, H.-J. and Michelssen, H.I. (2002) The crystal structure and mineralogical description of a Na-dominant komaro-vite from the Ilimaussaq alkaline complex. South Greenland. Neues Jahrbuch fiir Mineralogie, Monatshefte, 2002, 497–514.CrossRefGoogle Scholar
Becker, W.J. and Will, G. (1970) Rontgen-und Neutronenbeugungsuntersuchungen an Y2Ti2O7 . Zeitschrift fir Kristallographie, 131, 278–288.CrossRefGoogle Scholar
Bindi, L., Petficek, V., Withers, R.L., Zoppi, M. and Bonazzi, P. (2006) Novel high-temperature com-mensurate superstructure in natural bariopyrochlore: a structural study by means of a multiphase crystal structure refinement. Journal of Solid State Chemistry, 179, 716–725.CrossRefGoogle Scholar
Dal Piaz, G. (1935) La costituzione geologia dei Colli Euganei. Atti e Memorie dell Accademia Patavina di Scienze, Lettere ed Arti, 51, 11–19.Google Scholar
Downs, R.T., Bartelmehs, K.L., Gibbs, GV. and Boisen, M.B. Jr (1993) Interactive software for calculating and displaying X-ray or neutron powder diffract-ometer patterns of crystalline materials. American Mineralogist, 78, 1104–1107.Google Scholar
Dutta, P.K. and Shieh, D.C. (1985) Raman spectral study of the composition of basic silicate solutions. Applied Spectroscopy, 39, 343–346.CrossRefGoogle Scholar
Ercit, T.S., Hawthorne, F.C. and Cerny, P. (1994) The structural chemistry of kalipyrochlore, a “hydropyr-ochlore”. The Canadian Mineralogist, 32, 417–420.Google Scholar
Ferraris, G., Mackovicky, E. and Merlino, S. (2008) Crystallography of Modular Materials. Oxford University Press, Oxford, UK.CrossRefGoogle Scholar
Koleva, V. and Effenberger, H. (2007) Crystal chemistry of M[PO2(OH)2)]-2H2O compounds (M = Mg, Mn, Fe, Co, Ni, Zn, Cd): structural investigation of the Ni, Zn and Cd salts. Journal of Solid State Chemistry, 180, 956–967 CrossRefGoogle Scholar
Mandarino, J.A. (1976) The Gladstone—Dale relationship—part I: derivation of new constants. The Canadian Mineralogist, 14, 498–502.Google Scholar
Palatinus, L. and Chapuis, G (2007) Superflip— a computer program for the solution of crystal structures by charge flipping in arbitrary dimensions. Journal of Applied Crystallography, 40, 786–790.CrossRefGoogle Scholar
Pekov, I.V., Azarova, Y.V. and Chukanov, N. (2004) New data on komarovite series minerals. New Data on Minerals, 39, 5–13.Google Scholar
Rastsvetayeva, R.K., Tamezyan, R.A., Puscharovsky, D.Yu. and Nadeshina, T.M. (1994) Crystal structure and micro-twinning of K-rich nenadkevichite. European Journal of Mineralogy, 6, 503–509.CrossRefGoogle Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallographica, A32, 751–767.CrossRefGoogle Scholar
Sheldrick, GM. (2008) A short history of SHELX. Acta Crystallographica, A64, 112–122.Google Scholar
Sokolova, Y.V. and Yegorov-Tismenko, Y.K. (1990) Crystal structure of girvasite. Doklady Akadamii NaukSSSR, 331, 1372–1376.Google Scholar
Sokolova, E., Hawthorne, F.C. and Khomyakov, A.P. (2002) The crystal chemistry of fersmanite, Ca4(Na,Ca)4(Ti,Nb)4(Si2O7)2O8F3 . The Canadian Mineralogist, 40, 1421–1428.CrossRefGoogle Scholar
Stark, M. (1936) Kalksilikatgesteine bei Galzignano in den Euganeen. Neues Jahrbuch fir Mineralogie, Geologie und Paldontologie, 71, 342–361.Google Scholar
Su, Y., Lou Balmer, M. and Bunker, B.C. (2000) Raman spectroscopic studies of silicotitanates. Journal of Physical Chemistry B, 104, 8160–8169.CrossRefGoogle Scholar
Supplementary material: File

Cámara et al. supplementary material

Cámara tazzoliite CIF

Download Cámara et al. supplementary material(File)
File 29.5 KB