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Volume 68 
Part 1 
Pages i7-i8  
January 2012  

Received 23 November 2011
Accepted 7 December 2011
Online 14 December 2011

Key indicators
Single-crystal X-ray study
T = 293 K
Mean [sigma](Fe-O) = 0.001 Å
H completeness 83%
Disorder in main residue
R = 0.023
wR = 0.068
Data-to-parameter ratio = 16.4
Details
Open access

Pyrosmalite-(Fe), Fe8Si6O15(OH,Cl)10

aDepartment of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721-0077, USA, and bDepartment of Chemsitry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, Arizona 85721-0041, USA
Correspondence e-mail: hyang@u.arizona.edu

Pyrosmalite-(Fe), ideally FeII8Si6O15(OH,Cl)10 [refined composition in this study: Fe8Si6O15(OH0.814Cl0.186)10·0.45H2O, octairon(II) hexasilicate deca(chloride/hydroxide) 0.45-hydrate], is a phyllosilicate mineral and a member of the pyrosmalite series (Fe,Mn)8Si6O15(OH,Cl)10, which includes pyrosmalite-(Mn), as well as friedelite and mcgillite, two polytypes of pyrosmalite-(Mn). This study presents the first structure determination of pyrosmalite-(Fe) based on single-crystal X-ray diffraction data from a natural sample from Burguillos del Cerro, Badajos, Spain. Pyrosmalite-(Fe) is isotypic with pyrosmalite-(Mn) and its structure is characterized by a stacking of brucite-type layers of FeO6-octahedra alternating with sheets of SiO4 tetrahedra along [001]. These sheets consist of 12-, six- and four-membered rings of tetrahedra in a 1:2:3 ratio. In contrast to previous studies on pyrosmalite-(Mn), which all assumed that Cl and one of the four OH-groups occupy the same site, our data on pyrosmalite-(Fe) revealed a split-site structure model with Cl and OH occupying distinct sites. Furthermore, our study appears to suggest the presence of disordered structural water in pyrosmalite-(Fe), consistent with infrared spectroscopic data measured from the same sample. Weak hydrogen bonding between the ordered OH-groups that are part of the brucite-type layers and the terminal silicate O atoms is present.

Related literature

For pyrosmalite-(Fe), see: Zambonini (1901[Zambonini, F. (1901). Z. Kristallogr. 34, 554-561.]); Vaughan (1986[Vaughan, J. P. (1986). Mineral. Mag. 50, 527-531.]); Pan et al. (1993[Pan, Y., Fleet, M. E., Barnett, R. L. & Chen, Y. (1993). Can. Mineral. 31, 695-710.]). For other minerals of the pyrosmalite series, see: Frondel & Bauer (1953[Frondel, C. & Bauer, L. H. (1953). Am. Mineral. 38, 755-760.]); Stillwell & McAndrew (1957[Stillwell, F. & McAndrew, J. (1957). Mineral. Mag. 31, 371-380.]); Takéuchi et al. (1963[Takéuchi, Y., Kawada, I. & Sandanga, R. (1963). Acta Cryst. 16, A16.], 1969[Takéuchi, Y., Kawada, I., Irimaziri, S. & Sandanga, R. (1969). Miner. J. 5, 450-467.]); Kashaev & Drits (1970[Kashaev, A. A. & Drits, V. A. (1970). Sov. Phys. Crystallogr. 15, 40-43.]); Kashaev (1968[Kashaev, A. A. (1968). Sov. Phys. Crystallogr. 12, 923-924.]); Kato & Takéuchi (1983[Kato, T. & Takéuchi, Y. (1983). Can. Mineral. 21, 1-6.]); Kato & Watanabe (1992[Kato, T. & Watanabe, I. (1992). Yamaguchi Univ. College of Arts Bull. 26, 51-63.]); Ozawa et al. (1983[Ozawa, T., Takéuchi, Y., Takahata, T., Donnay, G. & Donnay, J. D. H. (1983). Can. Mineral. 21, 7-17.]); Abrecht (1989[Abrecht, J. (1989). Contrib. Mineral. Petrol. 103, 228-241.]); Kodera et al. (2003[Kodera, P., Murphy, P. J. & Rankin, A. H. (2003). Am. Mineral. 88, 151-158.]). Correlations between O-H streching frequencies and O-H...O donor-acceptor distances were given by Libowitzky (1999[Libowitzky, E. (1999). Monatsh. Chem. 130, 1047-1059.]). The presence of H2O in the pyrosmalite series was proposed by Kayupova (1964[Kayupova, M. M. (1964). Dokl. Akad. Nauk SSSR, 159, 82-85.]).

Experimental

Crystal data
  • Fe8Si6O15(OH0.814Cl0.186)10·0.45H2O

  • Mr = 1067.35

  • Trigonal, [P \overline 3m 1]

  • a = 13.3165 (2) Å

  • c = 7.0845 (2) Å

  • V = 1087.98 (4) Å3

  • Z = 2

  • Mo K[alpha] radiation

  • [mu] = 5.85 mm-1

  • T = 293 K

  • 0.09 × 0.08 × 0.08 mm

Data collection
  • Bruker APEXII CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 2005[Sheldrick, G. M. (2005). SADABS. University of Göttingen, Germany.]) Tmin = 0.622, Tmax = 0.653

  • 13410 measured reflections

  • 1476 independent reflections

  • 1141 reflections with I > 2[sigma](I)

  • Rint = 0.032

Refinement
  • R[F2 > 2[sigma](F2)] = 0.023

  • wR(F2) = 0.068

  • S = 1.05

  • 1476 reflections

  • 90 parameters

  • All H-atom parameters refined

  • [Delta][rho]max = 0.65 e Å-3

  • [Delta][rho]min = -0.56 e Å-3

Table 1
Hydrogen-bond geometry (Å, °)

D-H...A D-H H...A D...A D-H...A
OH2-H1...O3 0.88 (4) 2.42 (4) 3.224 (2) 152 (3)
OH3-H2...O2 0.85 (4) 2.14 (4) 2.980 (2) 170 (3)
OH4-H3...O2i 1.03 (5) 2.66 (2) 3.247 (2) 117 (1)
OH4-H3...O2ii 1.03 (5) 2.66 (2) 3.247 (2) 117 (1)
OH4-H3...O2iii 1.03 (5) 2.66 (2) 3.247 (2) 117 (1)
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) y, -x+y+1, -z+1; (iii) x-y, x, -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: WM2570 ).


Acknowledgements

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

References

Abrecht, J. (1989). Contrib. Mineral. Petrol. 103, 228-241.  [CrossRef] [ChemPort] [ISI]
Bruker (2004). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.
Downs, R. T. & Hall-Wallace, M. (2003). Am. Mineral. 88, 247-250.  [ChemPort]
Frondel, C. & Bauer, L. H. (1953). Am. Mineral. 38, 755-760.  [ChemPort]
Kashaev, A. A. (1968). Sov. Phys. Crystallogr. 12, 923-924.
Kashaev, A. A. & Drits, V. A. (1970). Sov. Phys. Crystallogr. 15, 40-43.
Kato, T. & Takéuchi, Y. (1983). Can. Mineral. 21, 1-6.  [ChemPort]
Kato, T. & Watanabe, I. (1992). Yamaguchi Univ. College of Arts Bull. 26, 51-63.
Kayupova, M. M. (1964). Dokl. Akad. Nauk SSSR, 159, 82-85.
Kodera, P., Murphy, P. J. & Rankin, A. H. (2003). Am. Mineral. 88, 151-158.  [ChemPort]
Libowitzky, E. (1999). Monatsh. Chem. 130, 1047-1059.  [CrossRef] [ChemPort]
Ozawa, T., Takéuchi, Y., Takahata, T., Donnay, G. & Donnay, J. D. H. (1983). Can. Mineral. 21, 7-17.  [ChemPort]
Pan, Y., Fleet, M. E., Barnett, R. L. & Chen, Y. (1993). Can. Mineral. 31, 695-710.  [ChemPort]
Sheldrick, G. M. (2005). SADABS. University of Göttingen, Germany.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.  [CrossRef] [details]
Stillwell, F. & McAndrew, J. (1957). Mineral. Mag. 31, 371-380.  [CrossRef] [ChemPort]
Takéuchi, Y., Kawada, I., Irimaziri, S. & Sandanga, R. (1969). Miner. J. 5, 450-467.
Takéuchi, Y., Kawada, I. & Sandanga, R. (1963). Acta Cryst. 16, A16.
Vaughan, J. P. (1986). Mineral. Mag. 50, 527-531.  [CrossRef] [ChemPort]
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.  [ISI] [CrossRef] [ChemPort] [details]
Zambonini, F. (1901). Z. Kristallogr. 34, 554-561.  [ChemPort]


Acta Cryst (2012). E68, i7-i8   [ doi:10.1107/S1600536811052822 ]

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