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Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): i60–i61.
Published online 2008 August 23. doi:  10.1107/S1600536808026676
PMCID: PMC2960593

Redetermination of olivenite from an untwinned single-crystal

Abstract

The crystal structure of olivenite, ideally Cu2(AsO4)(OH) [dicopper(II) arsenate(V) hydroxide], was redetermined from an untwinned and phosphate-containing natural sample, composition Cu2(As0.92P0.08O4), from Majuba Hill (Nevada, USA). Olivenite is structurally analogous with the important rock-forming mineral andalusite, Al2OSiO4. Its structure consists of chains of edge-sharing, distorted [CuO4(OH)2] octa­hedra extending parallel to [001]. These chains are cross-linked by isolated AsO4 tetra­hedra through corner-sharing, forming channels in which dimers of edge-sharing [CuO4(OH)] trigonal bipyramids are located. The structure is stabilized by medium to weak O—H(...)O hydrogen bonds. In contrast to the previous refinements from powder and single crystal X-ray data, all non-H atoms were refined with anisotropic displacement parameters and the H atom was located.

Related literature

For olivenite, see: Heritsch (1938 [triangle]); Richmond (1940 [triangle]); Berry (1951 [triangle]); Walitzi (1963 [triangle]); Toman (1977 [triangle]); Burns & Hawthorne (1995 [triangle]). For other minerals of the olivenite group, see: Hill (1976 [triangle]); Cordsen (1978 [triangle]); Frost et al. (2002 [triangle]). For correlations between O—H stretching frequencies and O—H(...)O donor–acceptor distances, see: Libowitzky (1999 [triangle]). For general background, see: Robinson et al. (1971 [triangle]).

Experimental

Crystal data

  • Cu2[(As0.92·P0.08)O4]OH
  • M r = 278.61
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-00i60-efi1.jpg
  • a = 8.5844 (3) Å
  • b = 8.2084 (3) Å
  • c = 5.9258 (2) Å
  • α = 90.130 (2)°
  • V = 417.56 (3) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 17.32 mm−1
  • T = 293 (2) K
  • 0.06 × 0.05 × 0.05 mm

Data collection

  • Bruker APEX2 CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2005 [triangle]) T min = 0.425, T max = 0.480 (expected range = 0.372–0.421)
  • 7604 measured reflections
  • 1580 independent reflections
  • 1372 reflections with I > 2σ(I)
  • R int = 0.029

Refinement

  • R[F 2 > 2σ(F 2)] = 0.020
  • wR(F 2) = 0.045
  • S = 1.10
  • 1580 reflections
  • 80 parameters
  • All H-atom parameters refined
  • Δρmax = 0.55 e Å−3
  • Δρmin = −0.84 e Å−3

Data collection: APEX2 (Bruker, 2003 [triangle]); cell refinement: SAINT (Bruker, 2005 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: XtalDraw (Downs & Hall-Wallace, 2003 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).

Table 1
Selected bond lengths (Å)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536808026676/wm2187sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808026676/wm2187Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors gratefully acknowledge the support of this study from the RRUFF project.

supplementary crystallographic information

Comment

Olivenite, ideally Cu2(AsO4)(OH), is a common secondary mineral of the oxidized zone of hydrothermal deposits. It crystallizes with monoclinic symmetry in space group P21/n with a pseudo-orthorhombic cell (β~ 90°). Several arsenates and phosphates belong to the olivenite mineral group, including adamite, Zn2(AsO4)(OH), eveite, Mn2+2(AsO4)(OH), libethenite, Cu2(PO4)(OH), zincolibethenite, CuZn(PO4)OH, and zincolivenite, CuZn(AsO4)(OH). Interestingly, except olivenite, all other minerals in this group display orthorhombic symmetry and crystallize in space group Pnnm. The first approximate structure determination of olivenite was reported by Heritsch (1938) in space group Pnnm. Subsequent studies on olivenite, however, proposed various other space groups: P212121 (Richmond, 1940), Pnmm (Berry, 1951), and Pn21m (Walitzi, 1963). Toman (1977) proposed that olivenite has actually monoclinic symmetry, and that most of the crystals are twinned. Structure refinements based on single-crystal X-ray diffraction data, uncorrected and corrected for twinning, yielded reliability factors R(F) of 0.090 and 0.065, respectively. However, Toman (1977) did not report any atomic displacement parameters or the position of the H atom. To avoid the complication of interpreting X-ray diffraction intensity data due to twinning, Burns & Hawthorne (1995) performed structure refinements of olivenite using the Rietveld method from powder X-ray diffraction data. By assuming a single isotropic displacement parameter for all O atoms and no H atom position, they attempted refinements both in space group Pnnm and P21/n and obtained nearly identical RBragg factors (~ 0.074) and goodness-of-fit values (~ 2.30). In our efforts to understand the relationships between the hydrogen environments and Raman spectra of hydrous minerals, we concluded that the structural information of olivenite needs to be improved. During the course of sample identification for the RRUFF project, we discovered an untwinned and phosphate-containing single-crystal of olivenite from Majuba Hill, Pershing County, Nevada, USA, and conducted a detailed structure refinement.

The structure of olivenite consists of chains of edge-sharing [Cu2O4(OH)2] octahedra extending parallel to [001] that are cross-linked by sharing corners with isolated AsO4 tetrahedra to form an open framework. Channels in the framework contain dimers of edge-sharing [Cu1O4(OH)] trigonal bipyramids that share corners with the [Cu2O4(OH)2] octahedra and AsO4 tetrahedra (Fig. 1). Although the average <As1—O>, <Cu1—O>, and <Cu2—O> distances of our study agree well with those given by Toman (1977) and Burns & Hawthorne (1995), the corresponding individual bond distances and angles from the three structure refinements (including ours) vary significantly. For example, the shortest and longest As—O bond distances within the AsO4 tetrahedra are 1.618 Å (As—O5) and 1.731 Å (As—O4), respectively, from Toman (1977), 1.640 Å (As—O4) and 1.702 Å (As—O1) from Burns & Hawthorne (1995), and 1.6479 (18) Å (As—O4) and 1.6866 (16) Å (As—O2) from this study. The shortest Cu—O bond length within the [Cu1O4(OH)] trigonal bipyramid is 1.9466 (18) Å (Cu1—O1) from this study, but is 1.917 Å (Cu1—O3) from Toman (1977) and 1.938 Å (Cu1—O5) from Burns & Hawthorne (1995). Furthermore, the AsO4 tetrahedron reported by Burns & Hawthorne (1995) is remarkably distorted, as measured by the tetrahedral angle variance (TAV) and quadratic elongation (TQE) (Robinson et al., 1971), which are 105.3 and 1.0281, respectively. In comparison, the TAV and TQE values are 6.1 and 1.0027, respectively, from Toman (1977), and 2.8 and 1.0008 from this study.

The H atom is bonded to O3, at a separation of 0.67 (4) Å. This distance is in fairly agreement with that (0.77 Å) reported for adamite (Hill, 1976). Our Raman spectra of olivenite (http://rruff.info/olivenite/R040181) show two major bands in the hydroxyl stretching (νOH) region: one at 3440 cm-1 and the other at 3464 cm-1. Similar wavenumbers (νOH= 3437 and 3464 cm-1) were also obtained by Frost et al. (2002). Given the correlation between νOH and O—H···O distances in minerals (Libowitzky, 1999), one would expect two O—H···O distances between 2.8 and 2.9 Å in olivenite. Our structural data indeed show that the O3(=OH) atom is at a distance of 2.79 Å from O4 and 2.98 Å from O5. Nevertheless, the angles O3—H···O4 (125°) and O3—H···O5 (112°) appear to be too small for hydrogen bonding. Note that, based on the structure refinement of libethenite, the phosphate analogue of olivenite, Cordsen (1978) proposed a bifurcated hydrogen bonding model for this mineral, in which there are two O—H···O bonds at the same distance of 2.84 Å and two bonding angles of 110°.

Experimental

The olivenite crystal used in this study is from Majuba Hill, Pershing County, Nevada (USA) and is a sample from the RRUFF project (deposition No. R040181; http//rruff.info). The chemical composition, (Cu0.980.02)2(As0.90P0.10O4)(OH)0.92, was determined with a CAMECA SX50 electron microprobe (http//rruff.info).

Refinement

The setting in P21/n11 with the a-axis as the monoclinic axis was chosen to keep consistency with previous studies on this mineral (Toman, 1977; Burns & Hawthorne, 1995). The minor vacancies for Cu and OH determined from electron microprobe analysis were ignored during the final refinement and all corresponding sites were assumed to be fully occupied. The relative ratio of As versus P at the As1 site was allowed to vary freely, with the sum of site occupation factors constrained to unity. The results agree well with those obtained from electron microprobe analysis. The H atom was located in a difference Fourier map, and its position was refined freely. The highest residual peak in the difference Fourier maps was located 0.80 Å from atom O1, and the deepest hole was located 0.63 Å from Cu1.

Figures

Fig. 1.
The crystal structure of olivenite given in the polyhedral representation. The H atoms (blue spheres) are drawn with an arbitrary radius.

Crystal data

Cu2[(As0.92·P0.08)O4]OHF000 = 521
Mr = 278.61Dx = 4.444 Mg m3
Monoclinic, P21/n11Mo Kα radiation λ = 0.71073 Å
Hall symbol: -P 2xnCell parameters from 1588 reflections
a = 8.5844 (3) Åθ = 3.9–30.1º
b = 8.2084 (3) ŵ = 17.32 mm1
c = 5.9258 (2) ÅT = 293 (2) K
β = 90ºEuhedral, equant, green
V = 417.56 (3) Å30.06 × 0.05 × 0.05 mm
Z = 4

Data collection

Bruker APEX2 CCD area-detector diffractometer1580 independent reflections
Radiation source: fine-focus sealed tube1372 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.029
T = 293(2) Kθmax = 33.1º
[var phi] and ω–scansθmin = 3.4º
Absorption correction: multi-scan(SADABS; Sheldrick, 2005)h = −12→13
Tmin = 0.425, Tmax = 0.480k = −12→12
7604 measured reflectionsl = −9→9

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: full  w = 1/[σ2(Fo2) + (0.0158P)2 + 0.4808P] where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.020(Δ/σ)max = 0.001
wR(F2) = 0.046Δρmax = 0.55 e Å3
S = 1.10Δρmin = −0.84 e Å3
1580 reflectionsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
80 parametersExtinction coefficient: 0.0009 (4)
Primary atom site location: structure-invariant direct methods

Special details

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)

xyzUiso*/UeqOcc. (<1)
As10.24984 (3)0.26286 (3)0.01069 (4)0.00764 (8)0.916 (3)
P10.24984 (3)0.26286 (3)0.01069 (4)0.00764 (8)0.084 (3)
Cu10.38101 (3)0.13699 (3)0.52383 (5)0.01125 (8)
Cu20.49966 (4)0.50071 (3)0.24933 (5)0.01022 (8)
O10.1070 (2)0.4010 (2)0.0500 (4)0.0148 (4)
O20.41871 (19)0.3677 (2)0.0022 (3)0.0103 (3)
O3H0.4028 (2)0.3734 (2)0.5002 (3)0.0095 (3)
O40.2470 (2)0.1303 (2)0.2191 (3)0.0144 (4)
O50.2226 (2)0.1661 (2)−0.2333 (3)0.0144 (4)
H10.329 (4)0.400 (5)0.510 (7)0.023 (10)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
As10.00795 (12)0.00743 (12)0.00753 (12)−0.00088 (8)−0.00011 (8)−0.00007 (8)
P10.00795 (12)0.00743 (12)0.00753 (12)−0.00088 (8)−0.00011 (8)−0.00007 (8)
Cu10.01148 (14)0.00725 (13)0.01503 (15)−0.00026 (10)0.00225 (11)−0.00003 (10)
Cu20.01370 (14)0.01085 (14)0.00612 (13)−0.00421 (10)−0.00003 (10)−0.00002 (10)
O10.0108 (8)0.0081 (7)0.0255 (10)0.0001 (6)−0.0006 (7)−0.0003 (7)
O20.0114 (7)0.0118 (8)0.0077 (8)−0.0054 (6)−0.0002 (6)0.0010 (6)
O3H0.0101 (8)0.0084 (7)0.0100 (8)0.0000 (6)0.0002 (6)0.0005 (6)
O40.0164 (8)0.0154 (8)0.0114 (8)−0.0059 (7)−0.0036 (6)0.0032 (7)
O50.0142 (8)0.0178 (9)0.0112 (8)−0.0047 (6)0.0022 (6)−0.0035 (7)

Geometric parameters (Å, °)

As1—O41.6479 (18)Cu2—O21.9526 (18)
As1—O51.6644 (19)Cu2—O2v1.9715 (17)
As1—O11.6855 (17)Cu2—O3Hvi1.9913 (18)
As1—O21.6866 (16)Cu2—O3H2.0001 (17)
Cu1—O1i1.9466 (18)Cu2—O5vii2.3439 (17)
Cu1—O3H1.9546 (18)Cu2—O4iii2.3874 (18)
Cu1—O5ii1.9940 (18)Cu2—Cu2v2.9549 (6)
Cu1—O1iii2.0132 (17)Cu2—Cu2vi2.9710 (6)
Cu1—O42.1418 (18)O3H—H10.67 (4)
Cu1—Cu1iv3.0509 (6)
O4—As1—O5109.53 (9)O3H—Cu2—O5vii86.14 (7)
O4—As1—O1109.30 (10)O2—Cu2—O4iii97.12 (7)
O5—As1—O1109.72 (9)O2v—Cu2—O4iii89.48 (7)
O4—As1—O2111.90 (8)O3Hvi—Cu2—O4iii78.52 (7)
O5—As1—O2109.70 (9)O3H—Cu2—O4iii94.30 (7)
O1—As1—O2106.63 (9)O5vii—Cu2—O4iii168.95 (7)
O1i—Cu1—O3H171.47 (7)As1—O1—Cu1viii128.31 (10)
O1i—Cu1—O5ii95.51 (8)As1—O1—Cu1ix124.56 (10)
O3H—Cu1—O5ii89.99 (8)Cu1viii—O1—Cu1ix100.78 (8)
O1i—Cu1—O1iii79.22 (8)As1—O2—Cu2124.61 (10)
O3H—Cu1—O1iii92.59 (7)As1—O2—Cu2v127.49 (10)
O5ii—Cu1—O1iii146.34 (8)Cu2—O2—Cu2v97.70 (7)
O1i—Cu1—O494.12 (8)Cu1—O3H—Cu2vi120.04 (9)
O3H—Cu1—O490.83 (7)Cu1—O3H—Cu2127.85 (10)
O5ii—Cu1—O4104.18 (8)Cu2vi—O3H—Cu296.20 (7)
O1iii—Cu1—O4109.33 (8)Cu1—O3H—H1103 (3)
O2—Cu2—O2v82.30 (7)Cu2vi—O3H—H199 (3)
O2—Cu2—O3Hvi175.64 (7)Cu2—O3H—H1107 (3)
O2v—Cu2—O3Hvi97.45 (7)As1—O4—Cu1127.46 (10)
O2—Cu2—O3H96.73 (7)As1—O4—Cu2ix111.74 (9)
O2v—Cu2—O3H176.19 (7)Cu1—O4—Cu2ix114.99 (8)
O3Hvi—Cu2—O3H83.80 (7)As1—O5—Cu1x125.98 (10)
O2—Cu2—O5vii93.79 (7)As1—O5—Cu2xi115.32 (9)
O2v—Cu2—O5vii90.25 (7)Cu1x—O5—Cu2xi117.06 (9)
O3Hvi—Cu2—O5vii90.56 (7)

Symmetry codes: (i) −x+1/2, y−1/2, z+1/2; (ii) x, y, z+1; (iii) x+1/2, −y+1/2, −z+1/2; (iv) −x+1, −y, −z+1; (v) −x+1, −y+1, −z; (vi) −x+1, −y+1, −z+1; (vii) −x+1/2, y+1/2, z+1/2; (viii) −x+1/2, y+1/2, z−1/2; (ix) x−1/2, −y+1/2, −z+1/2; (x) x, y, z−1; (xi) −x+1/2, y−1/2, z−1/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O3H—H1···O4vii0.67 (4)2.35 (4)2.788 (3)125 (4)
O3H—H1···O5vii0.67 (4)2.66 (4)2.977 (2)112 (4)

Symmetry codes: (vii) −x+1/2, y+1/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2187).

References

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