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Volume 69 
Part 2 
Pages i4-i5  
February 2013  

Received 6 December 2012
Accepted 23 December 2012
Online 9 January 2013

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Key indicators
Single-crystal X-ray study
T = 293 K
Mean [sigma](P-O) = 0.002 Å
Disorder in main residue
R = 0.015
wR = 0.039
Data-to-parameter ratio = 16.6
Details
Open access

Penikisite, BaMg2Al2(PO4)3(OH)3, isostructural with bjarebyite

Michael G. Bowman,a* Robert T. Downsa and Hexiong Yanga

aDepartment of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721-0077, USA
Correspondence e-mail: bowman90@email.arizona.edu

The bjarebyite group of minerals, characterized by the general formula BaX2Y2(PO4)3(OH)3, with X = Mg, Fe2+ or Mn2+, and Y = Al or Fe3+, includes five members: bjarebyite BaMn2+2Al2(PO4)3(OH)3, johntomaite BaFe2+2Fe3+2(PO4)3(OH)3, kulanite BaFe2+2Al2(PO4)3(OH)3, penikisite BaMg2Al2(PO4)3(OH)3, and perloffite BaMn2+2Fe3+2(PO4)3(OH)3. Thus far, the crystal structures of all minerals in the group, but penikisite, have been determined. The present study reports the first structure determination of penikisite (barium dimagnesium dialuminium triphosphate trihydroxide) using single-crystal X-ray diffraction data of a crystal from the type locality, Mayo Mining District, Yukon Territory, Canada. Penikisite is isotypic with other members of the bjarebyite group with space group P21/m, rather than triclinic (P1 or P-1), as previously suggested. Its structure consists of edge-shared [AlO3(OH)3] octahedral dimers linking via corners to form chains along [010]. These chains are decorated with PO4 tetrahedra (one of which has site symmetry m) and connected along [100] via edge-shared [MgO5(OH)] octahedral dimers and eleven-coordinated Ba2+ ions (site symmetry m), forming a complex three-dimensional network. O-H...O hydrogen bonding provides additional linkage between chains. Microprobe analysis of the crystal used for data collection indicated that Mn substitutes for Mg at the 1.5% (apfu) level.

Related literature

For penikisite, see: Mandarino et al. (1977[Mandarino, J. A., Sturman, B. D. & Corlett, M. I. (1977). Can. Mineral. 15, 393-395.]). For other mineral members in the bjarebyite group, see: Moore & Araki (1974[Moore, P. B. & Araki, T. (1974). Am. Mineral. 59, 567-572.]); Cooper & Hawthorne (1994[Cooper, M. & Hawthorne, F. C. (1994). Can. Mineral. 32, 15-19.]); Kolitsch et al. (2000[Kolitsch, U., Pring, A. & Tiekink, E. R. T. (2000). Mineral. Petrol. 70, 1-14.]); Elliott & Willis (2011[Elliott, P. & Willis, A. C. (2011). Mineral. Mag. 75, 317-325.]). 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

  • BaMg2Al2(PO4)3(OH)3

  • Mr = 576.77

  • Monoclinic, P 21 /m

  • a = 8.9577 (4) Å

  • b = 12.0150 (5) Å

  • c = 4.9079 (2) Å

  • [beta] = 100.505 (2)°

  • V = 519.37 (4) Å3

  • Z = 2

  • Mo K[alpha] radiation

  • [mu] = 4.72 mm-1

  • T = 293 K

  • 0.09 × 0.09 × 0.08 mm
Data collection

  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2005[Sheldrick, G. M. (2005). SADABS. University of Göttingen, Germany.]) Tmin = 0.676, Tmax = 0.704

  • 7681 measured reflections

  • 1970 independent reflections

  • 1925 reflections with I > 2[sigma](I)

  • Rint = 0.020
Refinement

  • R[F2 > 2[sigma](F2)] = 0.015

  • wR(F2) = 0.039

  • S = 1.14

  • 1970 reflections

  • 119 parameters

  • 1 restraint

  • All H-atom parameters refined

  • [Delta][rho]max = 0.72 e Å-3

  • [Delta][rho]min = -0.80 e Å-3

Table 1
Selected bond lengths (Å)

Mg-O7i 2.0591 (11)
Mg-O1ii 2.0864 (10)
Mg-O2iii 2.1227 (10)
Mg-OH9iv 2.1729 (11)
Mg-O5v 2.2090 (12)
Al-O3vi 1.8523 (11)
Al-O6 1.9080 (11)
Al-O5vii 1.9287 (10)
Al-OH9 1.9397 (11)
Al-OH9viii 1.9440 (11)
Al-OH8 1.9477 (7)
P1-O2 1.5232 (14)
P1-O1 1.5278 (15)
P1-O3 1.5321 (10)
P1-O3ix 1.5321 (10)
P2-O4 1.5083 (11)
P2-O7 1.5272 (11)
P2-O6 1.5443 (11)
P2-O5 1.5680 (10)
Symmetry codes: (i) [-x+1, y-{\script{1\over 2}}, -z+1]; (ii) x, y-1, z-1; (iii) x, y-1, z; (iv) [x, -y+{\script{1\over 2}}, z]; (v) [x, -y+{\script{1\over 2}}, z-1]; (vi) -x, -y+1, -z+1; (vii) x, y, z-1; (viii) -x, -y+1, -z; (ix) [x, -y+{\script{3\over 2}}, z].

Table 2
Hydrogen-bond geometry (Å, °)

D-H...A D-H H...A D...A D-H...A
OH8-H1...O6vii 0.79 (4) 2.66 (3) 3.3180 (16) 142 (1)
OH9-H2...O3 0.78 (3) 1.89 (3) 2.6512 (13) 166 (3)
Symmetry code: (vii) x, y, z-1.

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: HB7009 ).

Acknowledgements

The authors gratefully acknowledge support of this study by the Science Foundation Arizona.

References

Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Cooper, M. & Hawthorne, F. C. (1994). Can. Mineral. 32, 15-19.  [ChemPort]
Downs, R. T. & Hall-Wallace, M. (2003). Am. Mineral. 88, 247-250.  [ChemPort]
Elliott, P. & Willis, A. C. (2011). Mineral. Mag. 75, 317-325.  [CrossRef] [ChemPort]
Kolitsch, U., Pring, A. & Tiekink, E. R. T. (2000). Mineral. Petrol. 70, 1-14.  [ISI] [CrossRef] [ChemPort]
Mandarino, J. A., Sturman, B. D. & Corlett, M. I. (1977). Can. Mineral. 15, 393-395.
Moore, P. B. & Araki, T. (1974). Am. Mineral. 59, 567-572.  [ChemPort]
Robinson, K., Gibbs, G. V. & Ribbe, P. H. (1971). Science, 172, 567-570.  [CrossRef] [PubMed] [ChemPort] [ISI]
Sheldrick, G. M. (2005). SADABS. University of Göttingen, Germany.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [details]
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.  [ISI] [CrossRef] [ChemPort] [details]

Acta Cryst (2013). E69, i4-i5   [ doi:10.1107/S1600536812051793 ]

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