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Volume 68 
Part 11 
Pages i86-i87  
November 2012  

Received 6 October 2012
Accepted 23 October 2012
Online 27 October 2012

Key indicators
Single-crystal X-ray study
T = 293 K
Mean [sigma](As-O) = 0.001 Å
Disorder in main residue
R = 0.013
wR = 0.033
Data-to-parameter ratio = 14.7
Details
Open access

Redetermination of durangite, NaAl(AsO4)F

aUniversity High School, 421 N. Arcadia Avenue, Tucson, Arizona 85711-3032, USA,bCatalina Foothills High School, 4300 E. Sunrise Drive, Tucson, Arizona 85718-4300, USA, and cDepartment of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721-0077, USA
Correspondence e-mail: mabadean@terra.com.br

The crystal structure of durangite, ideally NaAl(AsO4)F (chemical name sodium aluminium arsenate fluoride), has been determined previously [Kokkoros (1938). Z. Kristallogr. 99, 38-49] using Weissenberg film data without reporting displacement parameters of atoms or a reliability factor. This study reports the redetermination of the structure of durangite using single-crystal X-ray diffraction data from a natural sample with composition (Na0.95Li0.05)(Al0.91Fe3+0.07Mn3+0.02)(AsO4)(F0.73(OH)0.27) from the type locality, the Barranca mine, Coneto de Comonfort, Durango, Mexico. Durangite is isostructural with minerals of the titanite group in the space group C2/c. Its structure is characterized by kinked chains of corner-sharing AlO4F2 octahedra parallel to the c axis. These chains are cross-linked by isolated AsO4 tetrahedra, forming a three-dimensional framework. The Na+ cation (site symmetry 2) occupies the interstitial sites and is coordinated by one F- and six O2- anions. The AlO4F2 octahedron has symmetry -1; it is flattened, with the Al-F bond length [1.8457 (4) Å] shorter than the Al-O bond lengths [1.8913 (8) and 1.9002 (9) Å]. Examination of the Raman spectra for arsenate minerals in the titanite group reveals that the position of the band originating from the As-O symmetric stretching vibrations shifts to lower wavenumbers from durangite, maxwellite [ideally NaFe(AsO4)F], to tilasite [CaMg(AsO4)F].

Related literature

For previous work on durangite, see: Brush (1869[Brush, G. J. (1869). Am. J. Sci. Arts, 98, 179-182.]); Des Cloizeaux (1875[Des Cloizeaux, M. (1875). Ann. Chim. Phys. 4, 401-406.]); Kokkoros (1938[Kokkoros, P. (1938). Z. Kristallogr. 99, 38-49.]); Machatschki (1941[Machatschki, F. (1941). Z. Kristallogr. 103, 221-227.]); Sumin de Portilla (1974[Sumin de Portilla, V. I. (1974). Can. Mineral. 12, 262-268.]); Foord et al. (1985[Foord, E. E., Oakman, M. R. & Maxwell, C. H. (1985). Can. Mineral. 23, 241-246.]). For minerals isostructural with or similar to durangite, see: Hawthorne (1990[Hawthorne, F. C. (1990). Z. Kristallogr. 192, 1-52.]); Groat et al. (1990[Groat, L. A., Raudsepp, M., Hawthorne, F. C., Ercit, T. S., Sherriff, B. L. & Hartman, J. S. (1990). Am. Mineral. 75, 992-1008.]); Hawthorne et al. (1991[Hawthorne, F. C., Groat, L. A., Raudsepp, M., Ball, N. A., Kimata, M., Spike, F. D., Gaba, R., Halden, N. M., Lumpkin, G. R., Ewing, R. C., Greegor, R. B., Lytle, F. W., Ercit, T. S., Rossman, G. R., Wicks, F. J., Ramik, R. A., Sherriff, B. L., Fleet, M. E. & McCammon, C. A. (1991). Am. Mineral. 76, 370-396.]); Oberti et al. (1991[Oberti, R., Smith, D. C., Rossi, G. & Caucia, F. (1991). Eur. J. Mineral. 3, 777-792.]); Bermanec (1994[Bermanec, V. (1994). Neues Jahrb. Miner. Mh. 1994, 289-294.]); Cooper & Hawthorne (1995[Cooper, M. A. & Hawthorne, F. C. (1995). Neues Jahrb. Miner. Mh. 1995, 97-104.]); Troitzsch et al. (1999[Troitzsch, U., Ellis, D. J., Thompson, J. & Fitz-Gerald, J. (1999). Eur. J. Mineral. 11, 955-965.]); Sebastian et al. (2002[Sebastian, L., Gopalakrishnan, J. & Piffard, Y. (2002). J. Mater. Chem. 12, 374-377.]). For Raman spectroscopic measurements on arsenate minerals and compounds, see: Yang et al. (2011a[Yang, H., Evans, S. H., Downs, R. T. & Jenkins, R. A. (2011a). Can. Mineral. 49, 687-696.],b[Yang, Y. W., Stevenson, R. A., Siegel, A. M. & Downs, G. W. (2011b). Acta Cryst. E67, i68.]); Frost & Xi (2012[Frost, R. L. & Xi, Y. (2012). Spectrochim. Acta Part A, 86, 224-230.]); Frost et al. (2012[Frost, R. L., Xi, Y., Tan, K., Millar, G. J. & Palmer, S. J. (2012). Spectrochim. Acta Part A, 85, 173-178.]). For the definition of polyhedral distortion, see: Robinson et al. (1971[Robinson, K., Gibbs, G. V. & Ribbe, P. H. (1971). Science, 172, 567-570.]).

Experimental

Crystal data
  • (Na0.95Li0.05)(Al0.91Fe0.09)(AsO4)(F0.73OH0.27)

  • Mr = 208.88

  • Monoclinic, C 2/c

  • a = 6.5789 (5) Å

  • b = 8.5071 (6) Å

  • c = 7.0212 (5) Å

  • [beta] = 115.447 (4)°

  • V = 354.83 (4) Å3

  • Z = 4

  • Mo K[alpha] radiation

  • [mu] = 10.18 mm-1

  • T = 293 K

  • 0.10 × 0.10 × 0.09 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2005[Sheldrick, G. M. (2005). SADABS. University of Göttingen, Germany.]) Tmin = 0.429, Tmax = 0.461

  • 2509 measured reflections

  • 645 independent reflections

  • 641 reflections with I > 2[sigma](I)

  • Rint = 0.019

Refinement
  • R[F2 > 2[sigma](F2)] = 0.013

  • wR(F2) = 0.033

  • S = 1.10

  • 645 reflections

  • 44 parameters

  • 3 restraints

  • H-atom parameters not refined

  • [Delta][rho]max = 0.65 e Å-3

  • [Delta][rho]min = -0.47 e Å-3

Data collection: APEX2 (Bruker, 2004[Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2004[Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: XtalDraw (Downs & Hall-Wallace, 2003[Downs, R. T. & Hall-Wallace, M. (2003). Am. Mineral. 88, 247-250.]); software used to prepare material for publication: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2690 ).


Acknowledgements

Support of this study was provided by the Arizona Science Foundation, CNPq 202469/2011-5 from the Brazilian government for MBA, and Bruker AXS for a summer work study by GWD and BNY. The durangite sample used in this study was kindly donated to the RRUFF Project by Michael Shannon.

References

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Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [details]
Sumin de Portilla, V. I. (1974). Can. Mineral. 12, 262-268.  [ChemPort]
Troitzsch, U., Ellis, D. J., Thompson, J. & Fitz-Gerald, J. (1999). Eur. J. Mineral. 11, 955-965.  [ChemPort]
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.  [ISI] [CrossRef] [ChemPort] [details]
Yang, H., Evans, S. H., Downs, R. T. & Jenkins, R. A. (2011a). Can. Mineral. 49, 687-696.
Yang, Y. W., Stevenson, R. A., Siegel, A. M. & Downs, G. W. (2011b). Acta Cryst. E67, i68.  [CrossRef] [details]


Acta Cryst (2012). E68, i86-i87   [ doi:10.1107/S160053681204384X ]

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