supplementary materials


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

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

K. Mereiter

Abstract top

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). 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.

Comment top

Tamarugite, NaAl(SO4)2·6H2O, is a secondary sulfate mineral which has been found in acidic environments generated by oxidation of sulfides like pyrite in the presence of alkali-rich aluminous rocks as Na and Al source. Classic occurrences of tamarugite are sulfate-rich weathering zones of sulfide ore deposits in the Atacama desert, Chile (Bandy, 1938). Other occurrences concern fumaroles, acid mine drainage, and burning coal dumps (Anthony et al., 2003). The mineral was first described from an occurrence in the Pampa del Tamarugal, Chile, from where it inherited its name (Anthony et al., 2003). The crystal structure of tamarugite was reported by Robinson & Fang (1969) as part of studies on the structural chemistry of salt hydrate minerals of Al3+ and Fe3+. Using diffraction data measured with a Buerger automated diffractometer (Weissenberg geometry, Cu Kα radiation), they obtained R[F] = 0.073 on 744 Fhkl with isotropic displacement parameters. They stated that hydrogen atom positions derived from stereochemical considerations were included in this refinement, but did neither report their coordinates nor corresponding geometric parameters.

The present structure redetermination was initiated when during an examination of sulfate mineral specimens from "Alcaparossa" (Mina Alcaparrosa near Cerritos Bayos, southwest of Calama, Chile; see Bandy, 1938) colourless crystals of good quality were encountered that turned out to be tamarugite. Unit cell setting and atom positions reported by Robinson & Fang (1969) were maintained in the present study. A comparison of previous (Robinson & Fang, 1969) and present structural data of tamarugite showed a fair agreement after taking into account that e.s.d.s for atomic coordinates were previously ca 20 times bigger than now, where standard deviations of the Na,Al,S—O bond lengths are about 0.001 Å. The largest difference between the two structures was 0.044 Å for the bond S2—O5 (Table 1). The differences between previous and present non-hydrogen atom positions are 0.018 Å on average and 0.054 Å for O5.

The crystal structure of tamarugite is built up from nearly regular [Al(H2O)6]3+ octahedra and an infinite two-strand chain of the composition [Na(SO4)2]3- extending along [001] (Fig. 1). Na is coordinated by six sulfate oxygen atoms with Na—O distances between 2.2709 (11) and 2.5117 (12) Å, mean value 2.42 Å (σ = 0.10 Å). Five of these six Na—O bonds are to the sulfate group S2O4 and only Na—O bond to the sulfate group S1O4. The coordination figure about Na can be described as a strongly distorted octahedron with cis bond angles between 57.26 (3) and 116.48 (4), and with trans bond angles between 135.96 (4) and 161.83 (5)°. This distortion is mostly due to the presence of a compact centrosymmetric group of two NaO6 octahedra and two S2O4 groups joined via five edge-sharing polyhedral links, one between two NaO6 octahedra and four between these two NaO6 octahedra and two adjacent SO4 tetrahedra (Fig. 1). Two corner-sharing links between NaO6 and S2O4 polyhedra via O6 expand this group into a two-stranded chain, to which at terminal position the S1O4 tetrahedron is attached via O3. The two independent sulfate groups S1O4 and S2O4 form relatively regular tetrahedra with S—O bond length in the range 1.4653 (10) – 1.4825 (10) Å and a mean bond length of S—O = 1.475 (7) Å. The O—S—O bond angles vary only over a narrow range of 3.3° (107.34 (6) – 110.61 (6)°). Six of the eight sulfate oxygen atoms are involved in two external bonds, either two hydrogen bonds (O1, O2, O4), or one Na—O and one hydrogen bond (O3, O6, O8). O5 is involved in one Na—O and two hydrogen bonds, and O7 in two Na—O and one hydrogen bonds. The [Al(H2O)6]3+ octahedron has a mean bond length of Al—O = 1.885 (11) Å, in good accord with the aluminium sulfate hydrates mendozite (NaAl(SO4)2.11H2O), sodium alum (NaAl(SO4)2.12H2O), alunogen (Al2(SO4)3.17H2O), and apjohnite (a Mn analogue of pickeringite, MgAl2(SO4)4.22H2O) (Fang & Robinson, 1972; Cromer et al., 1967; Menchetti & Sabelli, 1974, 1976). It is fairly regular by having cis bond angles of 85.98 (5) – 93.76 (6)° and trans bond angles of 173.97 (5) – 177.69 (5)°. The [Al(H2O)6]3+ octahedron donates twelve comparatively strong hydrogen bonds with O···O = 2.6665 (14) – 2.7971 (15) Å to the sulfate oxygen atoms of three neighbouring [Na(SO4)2]3- chains (Table 2). Eleven hydrogen bonds are largely linear having H···O = 1.78 – 2.00 Å and O—H···O = 156 – 178° (Table 2). Only the hydrogen bond O14W—H14A···O5viii is strongly bent due to the arrangement of the acceptor oxgen atom. It has therefore an outlying geometry with H···O = 2.18 Å and O—H···O = 129°. The next nearest oxygen neighbour of H14A, O3iii with H14A···O3iii = 2.65 Å, is not regarded as significantly bonded and therefore was not included in Table 2. The packing diagrams shown in Figs. 2 and 3 include all hydrogen bonds of the structure. Fig. 2 shows that each [Al(H2O)6]3+ is hydrogen bonded with three [Na(SO4)2]3- chains. Ten of the twelve different hydrogen bonds help to establish layers parallel to (010) with the composition {[Al(H2O)6][Na(SO4)2]2[Al(H2O)6]} and the range -1/4 < y < 1/4, 1/4 < y < 3/4, etc. At y 1/4 and 3/4 these layers are mutually linked via only two of the twelve different hydrogen bonds, O9W—H9b···O4v and O13W—H13b···O1vii (Figs. 2 and 3). These structural features agree with the preferentially tabular habit of crystals of tamarugite and their perfect cleavage on (010) (Anthony et al., 2003). For structural relationships between tamarugite (NaAl(SO4)2·6H2O), mendozite (NaAl(SO4)2.11H2O; contains trans-Na(H2O)4(SO4)2 groups and Al(H2O)6 octahedra), and sodium alum (NaAl(SO4)2.12H2O; contains Na(H2O)6 and Al(H2O)6 octahedra), the reader is referred to Fang & Robinson (1972).

Related literature top

For the previous structure determination of tamarugite, see: Robinson & Fang (1969). For mineralogical data of tamarugite, see: Anthony et al. (2003). For the mineralogy of three sulfate deposits of northern Chile including Mina Alcaparrosa, see: Bandy (1938). For the recently described new sulfate mineral alcaparrosite, see: Kampf et al. (2012). 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); Cromer et al. (1967); Menchetti & Sabelli (1974, 1976).

Experimental top

Tamarugite used in this study was on a specimen of copiapite and pickeringite from "Alcaparossa, Chile", this is Mina Alcaparrosa near Cerritos Bayos, southwest of Calama, Chile, a location that furnished many well crystallized Fe3+ sulfate hydrates (Bandy, 1938) and is type locality for the minerals paracoquimbite, parabutlerite and the new species alcaparrosite (K3Ti4+Fe3+(SO4)4O(H2O)2; Kampf et al., 2012).

Refinement top

All hydrogen atoms were clearly visible in a difference Fourier synthesis and refined satisfactorily without restraints. For the final calculations all water molecules were idealized to have O—H = 0.80 Å and H—O—H = 108.0° and were subsequently refined as rigid groups using AFIX 6 of program SHELXL97 (Sheldrick, 2008) with Uiso(H) unrestrained. This refinement method may be considered as an approach to describe the electron density distribution of a water molecule as a fixed aspheric entity that may optionally include idealized nuclear H positions for subsequent geometric calculations.

Computing details top

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. View of the two building blocks of tamarugite, the [Al(H2O)6]3+ octahedron and a segment of an infinite double-strand chain [Na(SO4)2]3- extending along [001]. Thermal displacement ellipsoids are shown at the 50% probability level. Symmetry operators: none x,y,z; (i) 1-x,-y,-z; (ii) x,y,-1+z; (iii) 1-x,-y,1-z.
[Figure 2] Fig. 2. The crystal structure of tamarugite in a projection along [001], the direction of the [Na(SO4)2]3- chains. Hydrogen bonds are shown as blue lines. Only the atoms of the asymmetric unit are labeled.
[Figure 3] Fig. 3. The crystal structure of tamarugite in a projection along [100]. Hydrogen bonds are shown as blue lines. Only the atoms of the asymmetric unit are labeled.
Sodium aluminium bis(sulfate) hexahydrate top
Crystal data top
NaAl(SO4)2·6H2OF(000) = 720
Mr = 350.19Dx = 2.047 Mg m3
Monoclinic, P21/aMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yabCell parameters from 8192 reflections
a = 7.3847 (3) Åθ = 2.5–30.0°
b = 25.2814 (15) ŵ = 0.66 mm1
c = 6.1097 (3) ÅT = 295 K
β = 94.85 (2)°Prism, colourless
V = 1136.57 (10) Å30.48 × 0.25 × 0.20 mm
Z = 4
Data collection top
Bruker SMART CCD
diffractometer
3316 independent reflections
Radiation source: fine-focus sealed tube2826 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.029
ω and φ scansθmax = 30.1°, θmin = 1.6°
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
h = 1010
Tmin = 0.74, Tmax = 0.88k = 3535
17967 measured reflectionsl = 88
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.025H-atom parameters constrained
wR(F2) = 0.061 w = 1/[σ2(Fo2) + (0.0304P)2 + 0.149P]
where P = (Fo2 + 2Fc2)/3
S = 1.14(Δ/σ)max = 0.001
3316 reflectionsΔρmax = 0.48 e Å3
194 parametersΔρmin = 0.36 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0154 (10)
Crystal data top
NaAl(SO4)2·6H2OV = 1136.57 (10) Å3
Mr = 350.19Z = 4
Monoclinic, P21/aMo Kα radiation
a = 7.3847 (3) ŵ = 0.66 mm1
b = 25.2814 (15) ÅT = 295 K
c = 6.1097 (3) Å0.48 × 0.25 × 0.20 mm
β = 94.85 (2)°
Data collection top
Bruker SMART CCD
diffractometer
3316 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1999)
2826 reflections with I > 2σ(I)
Tmin = 0.74, Tmax = 0.88Rint = 0.029
17967 measured reflectionsθmax = 30.1°
Refinement top
R[F2 > 2σ(F2)] = 0.025H-atom parameters constrained
wR(F2) = 0.061Δρmax = 0.48 e Å3
S = 1.14Δρmin = 0.36 e Å3
3316 reflectionsAbsolute structure: ?
194 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Na0.61674 (8)0.05252 (2)0.19574 (9)0.02332 (13)
Al0.14270 (5)0.145043 (15)0.67813 (6)0.01380 (9)
S10.64309 (4)0.183070 (12)0.20951 (5)0.01517 (8)
S20.70759 (4)0.020635 (12)0.75101 (5)0.01550 (8)
O10.56130 (13)0.22057 (4)0.04440 (16)0.0243 (2)
O20.81572 (14)0.16235 (5)0.13994 (16)0.0289 (2)
O30.51612 (15)0.13940 (4)0.23679 (18)0.0278 (2)
O40.68102 (15)0.21088 (4)0.42206 (16)0.0265 (2)
O50.70649 (14)0.03788 (4)0.73854 (17)0.0236 (2)
O60.75440 (14)0.04265 (4)0.53995 (15)0.0264 (2)
O70.52218 (13)0.03764 (4)0.79589 (16)0.0223 (2)
O80.83689 (14)0.03868 (4)0.93065 (16)0.0253 (2)
O9W0.12417 (13)0.18649 (4)0.41967 (15)0.01999 (19)
H9A0.04100.17990.33140.036 (5)*
H9B0.13940.21780.42050.060 (7)*
O10W0.06021 (14)0.08844 (4)0.49795 (18)0.0246 (2)
H10A0.12920.07120.43310.040 (6)*
H10B0.02710.07060.51430.048 (6)*
O11W0.38482 (13)0.12715 (4)0.63708 (16)0.01946 (19)
H11A0.42370.09920.68010.042 (6)*
H11B0.42250.13280.52040.040 (6)*
O12W0.09652 (13)0.16350 (4)0.73114 (15)0.0214 (2)
H12A0.16750.17930.64920.045 (6)*
H12B0.13630.16240.84890.047 (6)*
O13W0.23469 (14)0.20302 (4)0.84445 (17)0.0256 (2)
H13A0.33640.20440.90060.046 (6)*
H13B0.17440.22370.90580.047 (6)*
O14W0.13788 (16)0.09989 (5)0.92728 (18)0.0325 (3)
H14A0.21990.09951.02160.073 (8)*
H14B0.06850.07680.95250.18 (2)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Na0.0259 (3)0.0258 (3)0.0184 (3)0.0010 (2)0.0027 (2)0.0016 (2)
Al0.01271 (17)0.01541 (17)0.01329 (17)0.00230 (13)0.00115 (12)0.00043 (13)
S10.01638 (14)0.01529 (14)0.01387 (14)0.00107 (10)0.00146 (10)0.00165 (10)
S20.01550 (14)0.01615 (14)0.01499 (14)0.00061 (11)0.00212 (10)0.00103 (10)
O10.0220 (5)0.0237 (5)0.0256 (5)0.0051 (4)0.0067 (4)0.0106 (4)
O20.0211 (5)0.0454 (7)0.0203 (5)0.0096 (4)0.0034 (4)0.0031 (4)
O30.0329 (6)0.0194 (5)0.0319 (5)0.0057 (4)0.0081 (4)0.0045 (4)
O40.0352 (6)0.0237 (5)0.0193 (5)0.0096 (4)0.0046 (4)0.0045 (4)
O50.0261 (5)0.0171 (4)0.0283 (5)0.0034 (4)0.0063 (4)0.0015 (4)
O60.0256 (5)0.0366 (6)0.0171 (5)0.0108 (4)0.0021 (4)0.0051 (4)
O70.0183 (4)0.0212 (5)0.0278 (5)0.0055 (4)0.0044 (4)0.0043 (4)
O80.0227 (5)0.0335 (6)0.0192 (5)0.0048 (4)0.0018 (4)0.0011 (4)
O9W0.0221 (5)0.0184 (5)0.0188 (5)0.0015 (4)0.0020 (4)0.0039 (3)
O10W0.0216 (5)0.0194 (5)0.0344 (6)0.0046 (4)0.0113 (4)0.0084 (4)
O11W0.0171 (4)0.0198 (5)0.0222 (5)0.0050 (3)0.0056 (4)0.0032 (4)
O12W0.0164 (4)0.0321 (5)0.0160 (4)0.0080 (4)0.0024 (3)0.0024 (4)
O13W0.0164 (5)0.0289 (5)0.0305 (5)0.0057 (4)0.0050 (4)0.0138 (4)
O14W0.0282 (6)0.0436 (7)0.0260 (5)0.0095 (5)0.0041 (4)0.0168 (5)
Geometric parameters (Å, º) top
Na—O62.2709 (11)S2—O51.4814 (10)
Na—O32.3389 (12)S2—O71.4826 (10)
Na—O8i2.4153 (12)O5—Naii2.4814 (12)
Na—O5ii2.4814 (12)O7—Naii2.5020 (11)
Na—O7ii2.5020 (11)O7—Naiii2.5117 (12)
Na—O7i2.5117 (12)O8—Naiii2.4153 (12)
Al—O10W1.8755 (10)O9W—H9A0.80
Al—O13W1.8776 (11)O9W—H9B0.80
Al—O11W1.8816 (10)O10W—H10A0.80
Al—O12W1.8816 (10)O10W—H10B0.80
Al—O9W1.8904 (10)O11W—H11A0.80
Al—O14W1.9054 (11)O11W—H11B0.80
S1—O31.4671 (10)O12W—H12A0.80
S1—O21.4738 (10)O12W—H12B0.80
S1—O11.4759 (10)O13W—H13A0.80
S1—O41.4825 (10)O13W—H13B0.80
S2—O81.4653 (10)O14W—H14A0.80
S2—O61.4723 (10)O14W—H14B0.80
O6—Na—O397.20 (4)O2—S1—O4108.50 (6)
O6—Na—O8i109.33 (4)O1—S1—O4109.27 (6)
O3—Na—O8i116.48 (4)O8—S2—O6110.61 (6)
O6—Na—O5ii101.25 (4)O8—S2—O5110.48 (6)
O3—Na—O5ii78.70 (4)O6—S2—O5109.46 (6)
O8i—Na—O5ii142.95 (4)O8—S2—O7108.94 (6)
O6—Na—O7ii91.90 (4)O6—S2—O7109.95 (6)
O3—Na—O7ii135.96 (4)O5—S2—O7107.34 (6)
O8i—Na—O7ii100.49 (4)S1—O3—Na118.86 (6)
O5ii—Na—O7ii57.26 (3)S2—O5—Naii98.15 (5)
O6—Na—O7i161.83 (5)S2—O6—Na137.12 (6)
O3—Na—O7i100.38 (4)S2—O7—Naii97.25 (5)
O8i—Na—O7i58.24 (3)S2—O7—Naiii92.19 (5)
O5ii—Na—O7i86.73 (4)Naii—O7—Naiii101.38 (4)
O7ii—Na—O7i78.62 (4)S2—O8—Naiii96.57 (5)
O10W—Al—O13W176.35 (5)Al—O9W—H9A116.5
O10W—Al—O11W90.20 (5)Al—O9W—H9B122.9
O13W—Al—O11W87.45 (5)H9A—O9W—H9B108.0
O10W—Al—O12W91.56 (5)Al—O10W—H10A121.1
O13W—Al—O12W90.87 (5)Al—O10W—H10B125.6
O11W—Al—O12W177.69 (5)H10A—O10W—H10B108.0
O10W—Al—O9W86.31 (5)Al—O11W—H11A119.2
O13W—Al—O9W90.96 (5)Al—O11W—H11B118.8
O11W—Al—O9W91.40 (5)H11A—O11W—H11B108.0
O12W—Al—O9W90.21 (5)Al—O12W—H12A126.2
O10W—Al—O14W89.13 (6)Al—O12W—H12B124.6
O13W—Al—O14W93.76 (6)H12A—O12W—H12B108.0
O11W—Al—O14W92.56 (5)Al—O13W—H13A123.4
O12W—Al—O14W85.98 (5)Al—O13W—H13B125.0
O9W—Al—O14W173.97 (5)H13A—O13W—H13B108.0
O3—S1—O2110.00 (7)Al—O14W—H14A121.3
O3—S1—O1109.42 (6)Al—O14W—H14B130.3
O2—S1—O1110.20 (6)H14A—O14W—H14B108.0
O3—S1—O4109.43 (6)
Symmetry codes: (i) x, y, z1; (ii) x+1, y, z+1; (iii) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O9W—H9A···O2iv0.802.002.7971 (15)173
O9W—H9B···O4v0.801.832.6282 (14)178
O10W—H10A···O5ii0.801.872.6665 (14)173
O10W—H10B···O6iv0.801.782.5697 (14)169
O11W—H11A···O70.801.832.6315 (14)176
O11W—H11B···O30.801.932.7236 (14)175
O12W—H12A···O4iv0.801.892.6787 (14)171
O12W—H12B···O2vi0.801.842.6330 (14)169
O13W—H13A···O1iii0.801.862.6474 (14)169
O13W—H13B···O1vii0.801.882.6698 (14)171
O14W—H14A···O5viii0.802.182.7478 (15)129
O14W—H14B···O8iv0.801.962.7100 (17)156
Symmetry codes: (ii) x+1, y, z+1; (iii) x, y, z+1; (iv) x1, y, z; (v) x1/2, y+1/2, z; (vi) x1, y, z+1; (vii) x1/2, y+1/2, z+1; (viii) x+1, y, z+2.
Selected bond lengths (Å) top
Na—O62.2709 (11)Al—O9W1.8904 (10)
Na—O32.3389 (12)Al—O14W1.9054 (11)
Na—O8i2.4153 (12)S1—O31.4671 (10)
Na—O5ii2.4814 (12)S1—O21.4738 (10)
Na—O7ii2.5020 (11)S1—O11.4759 (10)
Na—O7i2.5117 (12)S1—O41.4825 (10)
Al—O10W1.8755 (10)S2—O81.4653 (10)
Al—O13W1.8776 (11)S2—O61.4723 (10)
Al—O11W1.8816 (10)S2—O51.4814 (10)
Al—O12W1.8816 (10)S2—O71.4826 (10)
Symmetry codes: (i) x, y, z1; (ii) x+1, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O9W—H9A···O2iii0.802.002.7971 (15)173.4
O9W—H9B···O4iv0.801.832.6282 (14)178.4
O10W—H10A···O5ii0.801.872.6665 (14)173.4
O10W—H10B···O6iii0.801.782.5697 (14)168.7
O11W—H11A···O70.801.832.6315 (14)175.7
O11W—H11B···O30.801.932.7236 (14)174.6
O12W—H12A···O4iii0.801.892.6787 (14)171.4
O12W—H12B···O2v0.801.842.6330 (14)169.4
O13W—H13A···O1vi0.801.862.6474 (14)169.3
O13W—H13B···O1vii0.801.882.6698 (14)171.4
O14W—H14A···O5viii0.802.182.7478 (15)128.8
O14W—H14B···O8iii0.801.962.7100 (17)156.3
Symmetry codes: (ii) x+1, y, z+1; (iii) x1, y, z; (iv) x1/2, y+1/2, z; (v) x1, y, z+1; (vi) x, y, z+1; (vii) x1/2, y+1/2, z+1; (viii) x+1, y, z+2.
Acknowledgements top

** intentionally no acknowledgement **

references
References top

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.

Fang, J. H. & Robinson, P. D. (1972). Am. Mineral. 57, 1081–1088.

Kampf, A. R., Mills, S. J., Housley, R. M. & Williams, P. A. (2012). Mineral. Mag. 76, 851–861.

Menchetti, S. & Sabelli, C. (1974). Tschermaks Miner. Petr. Mitt. 21, 164–178.

Menchetti, S. & Sabelli, C. (1976). Mineral. Mag. 40, 599–608.

Robinson, P. D. & Fang, J. H. (1969). Am. Mineral. 55, 19–30.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.