supporting information

Acta Cryst. (2013). E69, i15-i16    [ doi:10.1107/S1600536813003164 ]

Lanthanite-(Nd), Nd2(CO3)3·8H2O

S. M. Morrison, M. B. Andrade, M. D. Wenz, K. J. Domanik and R. T. Downs

Abstract top

Lanthanite-(Nd), ideally Nd2(CO3)3·8H2O [dineodymium(III) tricarbonate octa­hydrate], is a member of the lanthanite mineral group characterized by the general formula REE2(CO3)3·8H2O, where REE is a 10-coordinated rare earth element. Based on single-crystal X-ray diffraction of a natural sample from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan, this study presents the first structure determination of lanthanite-(Nd). Its structure is very similar to that of other members of the lanthanite group. It is composed of infinite sheets made up of corner- and edge-sharing of two NdO10-polyhedra (both with site symmetry ..2) and two carbonate triangles (site symmetries ..2 and 1) parallel to the ab plane, and stacked perpendicular to c. These layers are linked to one another only through hydrogen bonding involving the water mol­ecules.

Comment top

Crystals of the lanthanite group minerals exhibit a thin, platy habit and are characterized by the general formula REE2(CO3)3.8H2O, where REE is a 10-coordinated rare earth element. The group consists of lanthanite-(La), lanthanite-(Ce) and lanthanite-(Nd). The first of these minerals was found by Berzelius (1825) during one of his excursions to Bastnäs, Västmanland, Sweden, where he studied the local minerals and formulated the fundamentals of modern chemistry. Over 150 years later, Dal Negro et al. (1977) refined the crystal structure of the Bastnäs lanthanite and reported it in the non-standard setting Pbnb of space group No. 56. The chemistry of a different sample from this locality was later determined to be dominated by Ce (Atencio et al., 1989). Of the lanthanite group minerals, the structure of lanthanite-(Ce) is the only one previously determined from a natural sample. However, Shinn & Eick (1968) synthesized lanthanite-(La) and performed a refinement in the standard setting Pccn of space group No. 56.

Lanthanite-(Nd) from Bethlehem, Pennsylvania, US, was first described by Blake (1853), although it was not possible to discriminate the Nd-dominance at that time. It was not until Atencio et al. (1989) analyzed a Bethlehem sample that it was found to be Nd-rich. Lanthanite-(Nd) has since been reported from other localities, including Curitiba, Brazil (Coutinho, 1955; Ansell et al., 1976; Cesbron et al., 1979; Roberts et al., 1980; Fujimori, 1981; Svisero & Mascarenhas, 1981); Saga Prefecture, Japan (Nagashima et al., 1986); Santa Isabel, São Paulo, Brazil (Coimbra et al., 1989); and Whitianga, Coromandel Peninsula, New Zealand (Graham et al., 2007). With the exception of those found in Whitianga, all lanthanite-(Nd) samples from these localities, including the one used in this study, exhibit a predominance of Nd with sub-equal La and a notable depletion of Ce. In reference to this phenomenon, Atencio et al. (1989) stated that lanthanite minerals comprise two distinct groups: one in which the proportions of La, Ce and Nd are similar and another in which La and Nd are similar in abundance while Ce is severely depleted or entirely absent. This trend presumably stems from differences in formational conditions, but the exact mechanism(s) remain(s) unclear.

Many of the studies referenced above reported lanthanite-(Nd) unit-cell parameters, but none reported the crystal structure. This study presents the first crystal structure refinement of lanthanite-(Nd). In the course of identifying minerals for the RRUFF project (, we found an un-twinned lanthanite-(Nd) sample from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan and performed single-crystal X-ray diffraction.

The general structure feature of lanthanite-(Nd) is that of infinite sheets of corner- and edge-sharing NdO10- and carbonate-polyhedra (Fig. 1) parallel to the ab plane, and stacked perpendicular to c. The layers are linked to one another only by hydrogen bonding between water molecules (Fig. 2). This accounts for the micaceous cleavage of the lanthanite minerals (Fig. 3) (Dal Negro et al., 1977). There are two distinct Nd-sites (Nd1 and Nd2 at Wyckoff positions 4 c and 4 d), as well as two C-sites (C1 and C2 at Wyckoff positions 4 d and 8 e). Nd1 and Nd2 share an edge (O3 and O4) in the a-direction, forming a chain. The chains are linked in the b-direction by NdO10 polyhedra sharing a corner (O5) and sharing edges with the C2 carbonate group. Nd1 is bonded to two water molecules (OW1 and OW2) while Nd2 is bonded to one (OW3) that protrude from the primary sheet in the c-direction. The C1 carbonate group also projects from the sheet along c. According to bond valence calculations (Brese & O'Keeffe, 1991), without accounting for hydrogen bonding, each O-atom of the C1 carbonate group is under-bonded, with bond valence sums of 1.64 and 1.47 bond valence units for O1 and O2, respectively. The two O1 atoms are bonded only to Nd2 and C1, resulting in an underbonding that is satisfied by hydrogen bonding as an acceptor of OW1 and OW2 (Table 1). The apex O-atom, O2, is not bonded to any cation other than C1 and therefore has much larger thermal displacement parameters and a shorter bond length (1.243 (8) Å) than usually found in carbonate groups. The C1—O2 bond is close to satisfying the rigid-body criteria of equal displacement amplitudes of C1 and O2 along the C1—O2 bond direction. The bond length, corrected for rigid-body motion is 1.268 Å (Downs et al., 1992). O2 is also the acceptor of an hydrogen bond from the OW3 atom of the adjacent sheet, thus connecting the two sheets. There are not many minerals with dangling O atoms in CO3 groups, but these features are also observed in the crystal structures of isotypic lanthanite-(La) (Shinn & Eick, 1968), lanthanite-(Ce) (Dal Negro et al., 1977) and in dawsonite, NaAlCO3(OH)2 (Corazza et al., 1977). The last water molecule, OW4, is not bonded to any cation, but instead is situated between the OW1 of a given polyhedral layer and OW2 of the adjacent layer, linking the two layers together through hydrogen bonds.

Related literature top

For background to the lanthanite mineral group, see: Berzelius (1825); Blake (1853); Coutinho (1955); Shinn & Eick (1968); Ansell et al. (1976); Dal Negro et al. (1977); Cesbron et al. (1979); Roberts et al. (1980); Fujimori (1981); Svisero & Mascarenhas (1981); Nagashima et al. (1986); Atencio et al. (1989); Coimbra et al. (1989); Graham et al. (2007). For information on dawsonite, see: Corazza et al. (1977). For details of rigid-body motion, see: Downs et al. (1992). For resources for bond-valance calculations, see: Brese & O'Keeffe (1991).

Experimental top

The lanthanite-(Nd) specimen used in this study was from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan, and is in the collection of the RRUFF project (deposition No. R060993; The experimental empirical formula, (Nd0.95La0.61Pr0.17Sm0.12Gd0.08Y0.04Eu0.03)Σ=2(CO3)3.7.97H2O, was based on 17 O atoms and was determined from data of a CAMECA SX100 electron microprobe at the conditions of 15 keV, 10 nA, and a beam size of 20 µm. An average of 23 analysis points yielded (wt. %): H2O 23.50 (by difference), CO2 21.60, Y2O3 0.70, La2O3 16.32, Pr2O3 4.56, Nd2O3 26.06, Sm2O3 3.49, Eu2O3 0.87, Gd2O3 2.40, Tb2O3 0.12, Dy2O3 0.45.

Refinement top

Due to similar X-ray scattering lengths, all rare earth elements were treated as Nd. The highest residual peak in the difference Fourier maps was located at (1/4, 3/4, 0.3413), 1.03 Å from Nd2, and the deepest hole at (0.2515, 0.8358, 0.2813), 0.81 Å from Nd2. H-atoms from water molecules could not be assigned reliably and were excluded from refinement.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XtalDraw (Downs & Hall-Wallace, 2003); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
[Figure 1] Fig. 1. Looking down on a sheet of the lanthanite-(Nd) structure. NdO10 polyhedra are represented in blue and carbonate triangles are represented in green.
[Figure 2] Fig. 2. The crystal structure of lanthanite-(Nd) represented with displacement ellipsoids at the 99% probability level. Blue, green, red and cyan represent Nd, C, O atoms and H2O molecules, respectively.
[Figure 3] Fig. 3. Photograph of the lanthanite-(Nd) specimen analyzed in this study, illustrating its platy habit.
Dineodymium(III) tricarbonate octahydrate top
Crystal data top
Nd2(CO3)3·8H2OF(000) = 1160
Mr = 612.64Dx = 2.838 Mg m3
Orthorhombic, PccnMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ab 2acCell parameters from 6318 reflections
a = 8.9391 (4) Åθ = 2.3–27.5°
b = 9.4694 (4) ŵ = 7.25 mm1
c = 16.9374 (8) ÅT = 296 K
V = 1433.72 (11) Å3Platy, pink
Z = 40.20 × 0.18 × 0.02 mm
Data collection top
Bruker APEXII CCD area-detector
1570 independent reflections
Radiation source: fine-focus sealed tube1373 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.018
ϕ and ω scanθmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2005)
h = 1111
Tmin = 0.325, Tmax = 0.869k = 1011
9235 measured reflectionsl = 2119
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.020H-atom parameters not refined
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.0225P)2 + 5.4801P]
where P = (Fo2 + 2Fc2)/3
S = 1.12(Δ/σ)max = 0.001
1570 reflectionsΔρmax = 0.81 e Å3
102 parametersΔρmin = 0.59 e Å3
0 restraints
Crystal data top
Nd2(CO3)3·8H2OV = 1433.72 (11) Å3
Mr = 612.64Z = 4
Orthorhombic, PccnMo Kα radiation
a = 8.9391 (4) ŵ = 7.25 mm1
b = 9.4694 (4) ÅT = 296 K
c = 16.9374 (8) Å0.20 × 0.18 × 0.02 mm
Data collection top
Bruker APEXII CCD area-detector
1570 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2005)
1373 reflections with I > 2σ(I)
Tmin = 0.325, Tmax = 0.869Rint = 0.018
9235 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0200 restraints
wR(F2) = 0.057H-atom parameters not refined
S = 1.12Δρmax = 0.81 e Å3
1570 reflectionsΔρmin = 0.59 e Å3
102 parameters
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
Nd10.25000.25000.250082 (15)0.01450 (9)
Nd20.25000.75000.280450 (15)0.01381 (9)
C10.25000.75000.1061 (3)0.0211 (11)
C20.4597 (4)0.4972 (3)0.28322 (19)0.0142 (6)
O10.3229 (3)0.6575 (3)0.14676 (14)0.0181 (5)
O20.25000.75000.0327 (3)0.069 (2)
O30.0234 (3)0.3837 (3)0.20815 (16)0.0210 (5)
O40.0234 (3)0.6160 (3)0.23732 (16)0.0216 (5)
O50.3158 (3)0.4931 (3)0.29412 (15)0.0192 (5)
OW10.3170 (3)0.3820 (3)0.12154 (16)0.0232 (5)
OW20.1140 (3)0.3219 (3)0.37844 (16)0.0261 (6)
OW30.1241 (3)0.6457 (3)0.40530 (17)0.0343 (7)
OW40.3878 (6)0.3889 (5)0.4972 (3)0.0749 (15)
Atomic displacement parameters (Å2) top
Nd10.01417 (13)0.01111 (16)0.01822 (16)0.00172 (9)0.0000.000
Nd20.01354 (13)0.01037 (16)0.01752 (16)0.00126 (9)0.0000.000
C10.018 (2)0.022 (3)0.023 (3)0.003 (2)0.0000.000
C20.0165 (15)0.0119 (17)0.0143 (14)0.0004 (12)0.0013 (12)0.0014 (12)
O10.0181 (11)0.0150 (12)0.0212 (12)0.0022 (9)0.0017 (9)0.0018 (10)
O20.095 (5)0.094 (5)0.017 (2)0.070 (4)0.0000.000
O30.0224 (12)0.0121 (13)0.0284 (13)0.0055 (10)0.0016 (10)0.0001 (10)
O40.0188 (11)0.0131 (14)0.0329 (14)0.0039 (10)0.0022 (10)0.0029 (10)
O50.0128 (11)0.0165 (13)0.0284 (13)0.0006 (9)0.0027 (10)0.0008 (10)
OW10.0280 (13)0.0159 (13)0.0255 (13)0.0007 (11)0.0012 (11)0.0012 (10)
OW20.0171 (12)0.0357 (17)0.0254 (13)0.0010 (11)0.0007 (10)0.0006 (12)
OW30.0303 (15)0.050 (2)0.0228 (13)0.0153 (14)0.0008 (11)0.0011 (13)
OW40.089 (3)0.077 (3)0.059 (3)0.028 (3)0.035 (2)0.029 (2)
Geometric parameters (Å, º) top
Nd1—O52.491 (2)Nd2—O52.513 (2)
Nd1—O5i2.491 (2)Nd2—O1iv2.514 (2)
Nd1—O3i2.492 (2)Nd2—O12.514 (2)
Nd1—O32.492 (2)Nd2—OW3iv2.591 (3)
Nd1—OW1i2.581 (3)Nd2—OW32.591 (3)
Nd1—OW12.581 (3)Nd2—O3ii2.759 (3)
Nd1—OW22.582 (3)Nd2—O3v2.759 (3)
Nd1—OW2i2.582 (3)Nd2—C12.953 (6)
Nd1—O4ii2.762 (3)Nd2—C2iv3.040 (3)
Nd1—O4iii2.762 (3)C1—O21.243 (8)
Nd1—C23.051 (3)C1—O11.291 (4)
Nd1—C2i3.051 (3)C1—O1iv1.291 (4)
Nd2—O42.499 (3)C2—O4ii1.263 (4)
Nd2—O4iv2.499 (3)C2—O3ii1.272 (4)
Nd2—O5iv2.513 (2)C2—O51.300 (4)
O5—Nd1—O5i145.15 (12)O4iv—Nd2—O5109.18 (8)
O5—Nd1—O3i111.28 (8)O5iv—Nd2—O5169.43 (12)
O5i—Nd1—O3i78.92 (8)O4—Nd2—O1iv72.75 (8)
O5—Nd1—O378.92 (8)O4iv—Nd2—O1iv76.70 (8)
O5i—Nd1—O3111.28 (8)O5iv—Nd2—O1iv71.64 (8)
O3i—Nd1—O3146.88 (12)O5—Nd2—O1iv118.74 (8)
O5—Nd1—OW1i139.03 (8)O4—Nd2—O176.70 (8)
O5i—Nd1—OW1i75.53 (8)O4iv—Nd2—O172.75 (8)
O3i—Nd1—OW1i72.68 (8)O5iv—Nd2—O1118.74 (8)
O3—Nd1—OW1i79.45 (8)O5—Nd2—O171.64 (8)
O5—Nd1—OW175.53 (8)O1iv—Nd2—O151.48 (11)
O5i—Nd1—OW1139.03 (8)O4—Nd2—OW3iv141.63 (9)
O3i—Nd1—OW179.45 (8)O4iv—Nd2—OW3iv72.13 (9)
O3—Nd1—OW172.68 (8)O5iv—Nd2—OW3iv69.98 (9)
OW1i—Nd1—OW164.96 (12)O5—Nd2—OW3iv101.07 (10)
O5—Nd1—OW267.38 (8)O1iv—Nd2—OW3iv135.64 (9)
O5i—Nd1—OW283.13 (9)O1—Nd2—OW3iv139.06 (9)
O3i—Nd1—OW2139.15 (9)O4—Nd2—OW372.13 (9)
O3—Nd1—OW273.95 (8)O4iv—Nd2—OW3141.63 (9)
OW1i—Nd1—OW2136.78 (8)O5iv—Nd2—OW3101.07 (10)
OW1—Nd1—OW2133.78 (8)O5—Nd2—OW369.98 (9)
O5—Nd1—OW2i83.13 (9)O1iv—Nd2—OW3139.06 (9)
O5i—Nd1—OW2i67.38 (8)O1—Nd2—OW3135.64 (9)
O3i—Nd1—OW2i73.95 (8)OW3iv—Nd2—OW370.59 (13)
O3—Nd1—OW2i139.15 (9)O4—Nd2—O3ii120.36 (9)
OW1i—Nd1—OW2i133.78 (8)O4iv—Nd2—O3ii62.32 (9)
OW1—Nd1—OW2i136.78 (8)O5iv—Nd2—O3ii130.16 (8)
OW2—Nd1—OW2i65.29 (12)O5—Nd2—O3ii48.87 (7)
O5—Nd1—O4ii48.95 (8)O1iv—Nd2—O3ii116.91 (8)
O5i—Nd1—O4ii127.62 (8)O1—Nd2—O3ii70.95 (8)
O3i—Nd1—O4ii62.36 (9)OW3iv—Nd2—O3ii74.51 (9)
O3—Nd1—O4ii120.53 (9)OW3—Nd2—O3ii98.79 (9)
OW1i—Nd1—O4ii119.54 (8)O4—Nd2—O3v62.32 (9)
OW1—Nd1—O4ii68.74 (8)O4iv—Nd2—O3v120.36 (9)
OW2—Nd1—O4ii103.32 (8)O5iv—Nd2—O3v48.87 (7)
OW2i—Nd1—O4ii68.87 (8)O5—Nd2—O3v130.16 (8)
O5—Nd1—O4iii127.62 (8)O1iv—Nd2—O3v70.95 (8)
O5i—Nd1—O4iii48.95 (8)O1—Nd2—O3v116.91 (8)
O3i—Nd1—O4iii120.53 (9)OW3iv—Nd2—O3v98.79 (9)
O3—Nd1—O4iii62.36 (9)OW3—Nd2—O3v74.51 (9)
OW1i—Nd1—O4iii68.74 (8)O3ii—Nd2—O3v171.97 (11)
OW1—Nd1—O4iii119.54 (8)O2—C1—O1122.2 (2)
OW2—Nd1—O4iii68.87 (8)O2—C1—O1iv122.2 (2)
OW2i—Nd1—O4iii103.32 (8)O1—C1—O1iv115.5 (5)
O4ii—Nd1—O4iii171.14 (11)O4ii—C2—O3ii125.6 (3)
O4—Nd2—O4iv146.01 (13)O4ii—C2—O5117.4 (3)
O4—Nd2—O5iv109.18 (8)O3ii—C2—O5117.0 (3)
O4iv—Nd2—O5iv74.05 (8)O4ii—C2—O1113.5 (2)
O4—Nd2—O574.05 (8)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1/2, y+1, z+1/2; (iii) x, y1/2, z+1/2; (iv) x+1/2, y+3/2, z; (v) x, y+1/2, z+1/2.
Hydrogen-bond geometry (Å) top
OW1···O12.645 (4)
OW1···OW1i2.772 (5)
OW1···OW4vi2.792 (5)
OW1···OW3ii2.795 (4)
OW2···O1vii2.645 (3)
OW2···OW2i2.786 (5)
OW2···O52.815 (4)
OW2···OW4i2.833 (5)
OW3···O2viii2.626 (5)
OW3···OW1vii2.795 (4)
OW3···O52.928 (4)
OW3···OW3iv2.994 (6)
OW4···OW1ix2.792 (5)
OW4···OW2i2.833 (5)
OW4···OW4x2.909 (9)
OW4···OW2i3.231 (6)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1/2, y+1, z+1/2; (iv) x+1/2, y+3/2, z; (vi) x+1/2, y, z1/2; (vii) x1/2, y+1, z+1/2; (viii) x, y+3/2, z+1/2; (ix) x+1/2, y, z+1/2; (x) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formulaNd2(CO3)3·8H2O
Crystal system, space groupOrthorhombic, Pccn
Temperature (K)296
a, b, c (Å)8.9391 (4), 9.4694 (4), 16.9374 (8)
V3)1433.72 (11)
Radiation typeMo Kα
µ (mm1)7.25
Crystal size (mm)0.20 × 0.18 × 0.02
Data collection
DiffractometerBruker APEXII CCD area-detector
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2005)
Tmin, Tmax0.325, 0.869
No. of measured, independent and
observed [I > 2σ(I)] reflections
9235, 1570, 1373
(sin θ/λ)max1)0.649
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.057, 1.12
No. of reflections1570
No. of parameters102
H-atom treatmentH-atom parameters not refined
Δρmax, Δρmin (e Å3)0.81, 0.59

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), XtalDraw (Downs & Hall-Wallace, 2003), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top
OW1···O12.645 (4)
OW1···OW1i2.772 (5)
OW1···OW4ii2.792 (5)
OW1···OW3iii2.795 (4)
OW2···O1iv2.645 (3)
OW2···OW2i2.786 (5)
OW2···O52.815 (4)
OW2···OW4i2.833 (5)
OW3···O2v2.626 (5)
OW3···OW1iv2.795 (4)
OW3···O52.928 (4)
OW3···OW3vi2.994 (6)
OW4···OW1vii2.792 (5)
OW4···OW2i2.833 (5)
OW4···OW4viii2.909 (9)
OW4···OW2i3.231 (6)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1/2, y, z1/2; (iii) x+1/2, y+1, z+1/2; (iv) x1/2, y+1, z+1/2; (v) x, y+3/2, z+1/2; (vi) x+1/2, y+3/2, z; (vii) x+1/2, y, z+1/2; (viii) x+1, y+1, z+1.
Acknowledgements top

The authors gratefully acknowledge Marcus Origlieri for providing the lanthanite-(Nd) sample to the RRUFF Project. Funding support of this study was given by the Arizona Science Foundation, the Brazilian government (CNPq 202469/2011–5) and NASA NNX11AP82A, Mars Science Laboratory Investigations. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration.