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Volume 69 
Part 10 
Pages i63-i64  
October 2013  

Received 4 September 2013
Accepted 10 September 2013
Online 21 September 2013

Key indicators
Single-crystal X-ray study
T = 295 K
Mean [sigma](Al-O) = 0.001 Å
R = 0.025
wR = 0.061
Data-to-parameter ratio = 17.1
Details
Open access

Redetermination of tamarugite, NaAl(SO4)2·6H2O

aInstitute of Chemical Technology and Analytics, Vienna University of Technology, Getreidemarkt 9/164SC, A-1060 Vienna, Austria
Correspondence e-mail: kurt.mereiter@tuwien.ac.at

The crystal structure of tamarugite [sodium aluminium bis(sulfate) hexahydrate] was redetermined from a single crystal from Mina Alcaparossa, near Cerritos Bayos, southwest of Calama, Chile. In contrast to the previous work [Robinson & Fang (1969[Robinson, P. D. & Fang, J. H. (1969). Am. Mineral. 55, 19-30.]). Am. Mineral. 54, 19-30], all non-H atoms were refined with anisotropic displacement parameters and H-atoms were located by difference Fourier methods and refined from X-ray diffraction data. The structure is built up from nearly regular [Al(H2O)6]3+ octahedra and infinite double-stranded chains [Na(SO4)2]3- that extend parallel to [001]. The Na+ cation has a strongly distorted octahedral coordination by sulfate O atoms [Na-O = 2.2709 (11) - 2.5117 (12) Å], of which five are furnished by the chain-building sulfate group S2O4 and one by the non-bridging sulfate group S1O4. The [Na(SO4)2]3- chain features an unusual centrosymmetric group formed by two NaO6 octahedra and two S2O4 tetrahedra sharing five adjacent edges, one between two NaO6 octahedra and two each between the resulting double octahedron and two S2O4 tetrahedra. These groups are then linked into a double-stranded chain via corner-sharing between NaO6 octahedra and S2O4 tetrahedra. The S1O4 group, attached to Na in the terminal position, completes the chains. The [Al(H2O)6]3+ octahedron (<Al-O> = 1.885 (11) Å) donates 12 comparatively strong hydrogen bonds (O...O = 2.6665 (14) - 2.7971 (15) Å) to the sulfate O atoms of three neighbouring [Na(SO4)2]3- chains, helping to connect them in three dimensions, but with a prevalence parallel to (010), the cleavage plane of the mineral. Compared with the previous work on tamarugite, the bond precision of Al-O bond lengths as an example improved from 0.024 to 0.001 Å.

Related literature

For the previous structure determination of tamarugite, see: Robinson & Fang (1969[Robinson, P. D. & Fang, J. H. (1969). Am. Mineral. 55, 19-30.]). For mineralogical data of tamarugite, see: Anthony et al. (2003[Anthony, J. W., Bideaux, R. A., Bladh, K. W. & Nichols, M. C. (2003). Handbook of Mineralogy, Vol. V, Borates, Carbonates, Sulfates. Tucson: Mineral Data Publishing.]). For the mineralogy of three sulfate deposits of northern Chile including Mina Alcaparrosa, see: Bandy (1938[Bandy, M. C. (1938). Am. Mineral. 23, 669-760.]). For the recently described new sulfate mineral alcaparrosite, see: Kampf et al. (2012[Kampf, A. R., Mills, S. J., Housley, R. M. & Williams, P. A. (2012). Mineral. Mag. 76, 851-861.]). For crystal structures of the related aluminium sulfate hydrates mendozite [NaAl(SO4)2·11H2O], sodium alum [NaAl(SO4)2·12H2O], alunogen [Al2(SO4)3·17H2O] and apjohnite [MnAl2(SO4)4·22H2O], see: Fang & Robinson (1972[Fang, J. H. & Robinson, P. D. (1972). Am. Mineral. 57, 1081-1088.]); Cromer et al. (1967[Cromer, D. T., Kay, M. I. & Larson, A. C. (1967). Acta Cryst. 22, 182-187.]); Menchetti & Sabelli (1974[Menchetti, S. & Sabelli, C. (1974). Tschermaks Miner. Petr. Mitt. 21, 164-178.], 1976[Menchetti, S. & Sabelli, C. (1976). Mineral. Mag. 40, 599-608.]).

Experimental

Crystal data
  • NaAl(SO4)2·6H2O

  • Mr = 350.19

  • Monoclinic, P 21 /a

  • a = 7.3847 (3) Å

  • b = 25.2814 (15) Å

  • c = 6.1097 (3) Å

  • [beta] = 94.85 (2)°

  • V = 1136.57 (10) Å3

  • Z = 4

  • Mo K[alpha] radiation

  • [mu] = 0.66 mm-1

  • T = 295 K

  • 0.48 × 0.25 × 0.20 mm

Data collection
  • Bruker SMART CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.74, Tmax = 0.88

  • 17967 measured reflections

  • 3316 independent reflections

  • 2826 reflections with I > 2[sigma](I)

  • Rint = 0.029

Refinement
  • R[F2 > 2[sigma](F2)] = 0.025

  • wR(F2) = 0.061

  • S = 1.14

  • 3316 reflections

  • 194 parameters

  • H-atom parameters constrained

  • [Delta][rho]max = 0.48 e Å-3

  • [Delta][rho]min = -0.36 e Å-3

Table 1
Selected bond lengths (Å)

Na-O6 2.2709 (11)
Na-O3 2.3389 (12)
Na-O8i 2.4153 (12)
Na-O5ii 2.4814 (12)
Na-O7ii 2.5020 (11)
Na-O7i 2.5117 (12)
Al-O10W 1.8755 (10)
Al-O13W 1.8776 (11)
Al-O11W 1.8816 (10)
Al-O12W 1.8816 (10)
Al-O9W 1.8904 (10)
Al-O14W 1.9054 (11)
S1-O3 1.4671 (10)
S1-O2 1.4738 (10)
S1-O1 1.4759 (10)
S1-O4 1.4825 (10)
S2-O8 1.4653 (10)
S2-O6 1.4723 (10)
S2-O5 1.4814 (10)
S2-O7 1.4826 (10)
Symmetry codes: (i) x, y, z-1; (ii) -x+1, -y, -z+1.

Table 2
Hydrogen-bond geometry (Å, °)

D-H...A D-H H...A D...A D-H...A
O9W-H9A...O2iii 0.80 2.00 2.7971 (15) 173
O9W-H9B...O4iv 0.80 1.83 2.6282 (14) 178
O10W-H10A...O5ii 0.80 1.87 2.6665 (14) 173
O10W-H10B...O6iii 0.80 1.78 2.5697 (14) 169
O11W-H11A...O7 0.80 1.83 2.6315 (14) 176
O11W-H11B...O3 0.80 1.93 2.7236 (14) 175
O12W-H12A...O4iii 0.80 1.89 2.6787 (14) 171
O12W-H12B...O2v 0.80 1.84 2.6330 (14) 169
O13W-H13A...O1vi 0.80 1.86 2.6474 (14) 169
O13W-H13B...O1vii 0.80 1.88 2.6698 (14) 171
O14W-H14A...O5viii 0.80 2.18 2.7478 (15) 129
O14W-H14B...O8iii 0.80 1.96 2.7100 (17) 156
Symmetry codes: (ii) -x+1, -y, -z+1; (iii) x-1, y, z; (iv) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z]; (v) x-1, y, z+1; (vi) x, y, z+1; (vii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z+1]; (viii) -x+1, -y, -z+2.

Data collection: SMART (Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1999[Bruker (1999). SMART, SAINT and SADABS. 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: DIAMOND (Brandenburg, 2012[Brandenburg, K. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXL97 and 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: PJ2005 ).


References

Anthony, J. W., Bideaux, R. A., Bladh, K. W. & Nichols, M. C. (2003). Handbook of Mineralogy, Vol. V, Borates, Carbonates, Sulfates. Tucson: Mineral Data Publishing.
Bandy, M. C. (1938). Am. Mineral. 23, 669-760.
Brandenburg, K. (2012). DIAMOND. Crystal Impact GbR, Bonn, Germany.
Bruker (1999). SMART, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
Cromer, D. T., Kay, M. I. & Larson, A. C. (1967). Acta Cryst. 22, 182-187.  [CrossRef] [ChemPort] [IUCr Journals]
Fang, J. H. & Robinson, P. D. (1972). Am. Mineral. 57, 1081-1088.  [ChemPort]
Kampf, A. R., Mills, S. J., Housley, R. M. & Williams, P. A. (2012). Mineral. Mag. 76, 851-861.  [CrossRef] [ChemPort]
Menchetti, S. & Sabelli, C. (1974). Tschermaks Miner. Petr. Mitt. 21, 164-178.  [CrossRef] [ChemPort]
Menchetti, S. & Sabelli, C. (1976). Mineral. Mag. 40, 599-608.  [CrossRef] [ChemPort]
Robinson, P. D. & Fang, J. H. (1969). Am. Mineral. 55, 19-30.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [ChemPort] [IUCr Journals]
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.  [Web of Science] [CrossRef] [ChemPort] [IUCr Journals]


Acta Cryst (2013). E69, i63-i64   [ doi:10.1107/S1600536813025154 ]

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