Mineralogical Magazine, June 2013, Vol. 77(3), pp. 429–441

Leydetite, Fe(UO2)(SO4)2(H2O)11, a new uranyl sulfate
mineral from Mas d’Alary, Lodève, France
J. PLÁŠIL1,*, A. V. KASATKIN2, R. ŠKODA3, M. NOVÁK3, A. KALLISTOVÁ4, M. DUŠEK1, R. SKÁLA4, K. FEJFAROVÁ1,
J. ČEJKA5, N. MEISSER6, H. GOETHALS7, V. MACHOVIČ8,9 AND L. LAPČÁK8
1

Institute of Physics ASCR, v.v.i., Na Slovance 2, CZ-18221 Prague 8, Czech Republic
V/O ‘‘Almazjuvelirexport’’, Ostozhenka Street, 22, block 1, 119034 Moscow, Russia
3
Department of Geological Sciences, Faculty of Science, Masaryk University, Kotlářská 2, 4 611 37, Brno, Czech
Republic
4
Institute of Geology ASCR, v.v.i., Rozvojová 269, Prague 6, 16500, Czech Republic
5
Department of Mineralogy and Petrology, National Museum, Cirkusová 170, CZ-193 00, Prague 9, Czech Republic
6Musée géologique cantonal and Laboratoire des rayons-X, Institut de minéralogie et de géochimie, Université deLausanne, 1015 Lausanne-Dorigny, Switzerland
7
Musée de l’Institut royal des sciences naturelles de Belgique, Section mineralogy, Rue Vautier 29, 1000 Brussels,
Belgium
8
Institute of Chemical Technology, Prague, Technická 5, CZ 16628, Prague 6, Czech Republic
9Institute of Rock Structures and Mechanics ASCR, v.v.i., V Holešovičkách 41, CZ 18209, Prague 8, Czech
Republic
2[Received 18 February 2013; Accepted 25 March 2013; AE: S. Krivovichev]
ABSTRACT

Leydetite, monoclinic Fe(UO2)(SO4)2(H2O)11 (IMA 2012 065), is a new supergene uranyl sulfate fromMas d’Alary, Lodève, Hérault, France. It forms yellow to greenish, tabular, transparent to translucent
crystals up to 2 mm in size. Crystals have a vitreous lustre. Leydetite has a perfect cleavage on (001). The
streak is yellowish white. Mohs hardness is ~2. The mineral does not ﬂuoresce under long- or shortwavelength UV radiation. Leydetite is colourless in transmitted light, non-pleochroic, biaxial, with a =1.513(2), g = 1.522(2) (further optical properties could not be measured). The measured chemicalcomposition of leydetite, FeO 9.28, MgO 0.37, Al2O3 0.26, CuO 0.14, UO3 40.19, SO3 21.91, SiO2 0.18,
H 2 O 27.67, total 100 wt.%, leads to the empirical formula (based on 21 O a.p.f.u.),(Fe0.93Mg0.07Al0.04Cu0.01)S1.05(U1.01O2)(S1.96Si0.02)S1.98O8(H2O)11. Leydetite is monoclinic, space groupC2/c, with a = 11.3203(3), b = 7.7293(2), c = 21.8145(8) Å, b = 102.402(3)º, V = 1864.18(10) Å3, Z = 4,
and Dcalc = 2.55 g cm 3. The six strongest reﬂections in the X-ray powder diffraction pattern are [dobs in Å(I) (hkl)]: 10.625 (100) (002), 6.277 (1) (1̄11), 5.321 (66) (004), 3.549 (5) (006), 2.663 (4) (008), 2.131 (2)(0 0 10). The crystal structure has been reﬁned from single-crystal X-ray diffraction data to R1 = 0.0224
for 5211 observed reﬂections with [I > 3s(I)]. Leydetite possesses a sheet structure based upon theprotasite anion topology. The sheet consists of UO7 bipyramids, which share four of their equatorial
vertices with SO4 tetrahedra. Each SO4 tetrahedron, in turn, shares two of its vertices with UO7bipyramids. The remaining unshared equatorial vertex of the bipyramid is occupied by H2O, which
extends hydrogen bonds within the sheet to one of a free vertex of the SO4 tetrahedron. Sheets are stacked
perpendicular to the c direction. In the interlayer, Fe2+ ions and H2O groups link to the sheets on eitherside via a network of hydrogen bonds. Leydetite is isostructural with the synthetic compound
Mg(UO2)(SO4)2(H2O)11. The name of the new mineral honours Jean Claude Leydet (born 1961), an
amateur mineralogist from Brest (France), who discovered the new mineral.

* E-mail: plasil@fzu.cz
DOI: 10.1180/minmag.2013.077.4.03# 2013 The Mineralogical Society

J. PLÁŠIL ET AL.

K EY WORDS : leydetite, new mineral, uranyl sulfate, oxidation zone, crystal structure, Raman spectroscopy,

infrared spectroscopy, Mas d’Alary, Lodève.
Introduction
TWENTY uranyl sulfate minerals are currently
known. They are rare, but relatively widespread,due to the common association of sulﬁdeminerals, such as pyrite and chalcopyrite withuraninite. Among the uranyl sulfate minerals only
one, deliensite (Vochten et al., 1997; Plášil et al.,2012a), contains Fe2+ as an essential constituent.
Here, we present the description of the newmineral leydetite, a uranyl sulfate with medium
sized cations (Strunz class 07.EB) and the second
uranyl sulfate containing Fe2+ as an essential
constituent. The new mineral and the name wereapproved by the Commission on New minerals,
Nomenclature and Classiﬁcation of the IMA(IMA2012 065). It is named in honour of JeanClaude Leydet (born 1961), an amateur mineralogist and mineral collector from Brest, France.
Jean-Claude Leydet is especially known for his
studies of uranium-bearing minerals (Boisson andLeydet, 1998a,b; Leydet, 2006) and, in particular,
those of the Mas d’Alary deposit (Henriot andLeydet, 1998). In 1994 he discovered the newmineral deliensite (Vochten et al., 1997). In thesame year he collected the new mineral describedherein and named in his honour. The holotype
specimen of leydetite is deposited in thecollections of the Musée Cantonal de Géologie,
Lausanne, Switzerland, registration number MGL
92661.

Associated minerals include abundant pyrite,
less abundant uraninite (which however forms
omnipresent inclusions in coal), calcite, quartz,
unspeciﬁed clay minerals, gypsum and deliensite.
Physical and optical properties
Leydetite occurs as pale yellow to greenish,tabular, transparent to translucent crystals, up to
2 mm in size (Fig. 1). Crystals form multiple
intergrowths. The Mohs hardness of leydetite is~2. A density of 2.55 g cm 3 was calculated using
the empirical formula. Leydetite ﬂoats in
diodomethane with r = 3.32 g cm 3. Leydetite
is non-ﬂuorescent under short- or long-wavelength UV radiation. The streak is yellowish
white. Leydetite forms transparent to translucent
crystals with a strong vitreous lustre. Leydetite isbrittle and crystals exhibit excellent cleavage on(001). Intimate intergrowths of the crystals,
polysynthetic twinning and a perfect cleavage
did not allow feasible measurements of complete
optical properties. Leydetite is colourless andbiaxial; refractive indices were measured on
fragments with a perfect cleavage on (001), a’ =1.513(2) and g’ = 1.522(2) (590 nm) withbirefringence of 0.009. However, the absence ofany crystal fragment with refractive indices n >1.523 or n < 1.512 indicates that the measured
refractive indices a’ and g’ are close to a and g.

Occurrence
Leydetite was found at the Mas d’Alary uranium
deposit, Lodève, Hérault, France (43º42’33’’N;
03º20’12’’E). The deposit was opened andexploited as an open pit from June 1984 to July
1992 (Bavoux and Guiollard, 1999). Uranium ore
is found in grey Autunian sandstones, pelites andconglomerates. Local remobilization of U mineralization along fault zones is common in thedeposit. Due to major tectonic events in the area,
U-deposits in the Permian Lodève basin show acomplex evolution with at least three U-mobilization stages, culminating with the recent alterationby oxygenated surface and subsurface waters,
down to 30 m depth at Mas d’Alary (Deliens etal., 1990; Lancelot et al., 1995). Leydetite
probably formed during this last stage.

FIG. 1. Aggregate of leydetite crystals from Mas d’Alary,
Lodève, France. The dominating faces are {001}, then{010} and {100}. Faces {101} and {011} occur also(and their symmetrically related equivalents). Field ofview 2.5 mm. Photo by V. Bourgoin.

430

LEYDETITE, A NEW URANYL SULFATE MINERAL

Hence, to calculate the Gladstone-Dale compatibility, at least as a best estimate, an average
between a and g refractive indices was taken as
the b index, giving a calculated value of 1.518.
The Gladstone-Dale compatibility index(Mandarino, 1981), calculated using the abovementioned values and a density of 2.55 g cm 3,
is 0.016 (superior). The value of 2Vcalc is then83º (the mineral is probably biaxial positive).
Leydetite dehydrates readily in dry air, becoming
opaque and changing colour from yellow-green toorange-yellow.

which requires FeO 10.03, UO3 39.98, SO3 22.34,
H2O 27.65, total 100 wt.%. Leydetite is readilysoluble in 10% HCl. On addition of KSCN, no
colouration appeared, so it can be concluded themineral does not contain any Fe3+.
Infrared and Raman spectroscopy

Chemical composition
The chemical composition of leydetite wasdetermined using a Cameca SX100 electron
microprobe operating in the wavelength-dispersive mode with an acceleration voltage of 15 kV,beam current of 4 nA, and 15 mm beam diameter.
The following X-ray lines and standards wereselected to minimize line overlaps: FeKa
(hematite); CuLa (lammerite); MgKa
(Mg 2 SiO 4 ); Al, SiKa (sanidine); UMa(metallic U), SKa (SrSO4). Peak counting times
were 10 20 s and the counting time forbackground was 50% of the peak. The raw data
were converted to element concentrations using
the PAP routine (Pouchou and Pichoir, 1985).
Leydetite shows homogeneous chemicalcomposition (Table 1) and its empirical formula(based on 21 O a.p.f.u.) is (Fe0.93Mg0.07Al0.04
Cu0.01)S1.05(U1.01O2)(S1.96Si0.02)S1.98O8(H2O)11.
The simpliﬁed formula is Fe(UO2)(SO4)2(H2O)11,

The Raman spectrum (Fig. 2) of a leydetite
crystal was collected using a DXR dispersive
Raman spectrometer (ThermoElectron corp.)
mounted on a confocal Olympus microscope(1006objective) in the range 50 6400 cm 1(with a resolution of 2 cm 1). The Raman signal
was excited by a 532 nm laser and detected by a
CCD detector. Experimental parameters: exposure time, 10 s; number of exposures, 32; grating,
400 lines mm 1; spectrograph aperture, 50 mm
slit; laser power level: 2.5 mW. The infrared (IR)
spectrum (Fig. 3) was collected using the ATR
technique on a Nicolet 6700 FTIR spectrometercoupled to a Continuum microscope. The
spectrum was collected from 4000 650 cm 1with a resolution of 5 cm 1. Spectra were
processed (background correction, ﬁtting) using
the OMNIC Spectral tool software v.7.3(ThermoElectron Corp.). We based our interpretations of both Raman and IR spectra on thosepresented by Čejka (1999, 2004, 2007), Volod’ko
et al. (1965, 1981), Nakamoto (1986), Lane(2007) and Majzlan et al. (2011).
From a spectroscopic point of view, monoclinic leydetite contains in the primitive unit cell
(Wigner-Seitz cell, or the ﬁrst Brillouin zone) two

TABLE 1. Chemical composition (wt.%) of leydetite.
Mean
FeO
CuO
MgO
Al2O3
SiO2
SO3
UO3
H2O*
Total

10.88
0.16
0.43
0.31
0.21
25.68
47.10
32.65
117.40

Range
10.65
0.00
0.25
0.11
0.10
24.07
46.01
31.90
114.63

11.10
0.31
0.55
0.46
0.40
26.88
47.89
33.64
120.68SD

Mean (normalized
to 100 wt.%)

0.20
0.13
0.11
0.12
0.10
1.02
0.65
0.62

9.28
0.14
0.36
0.26
0.18
21.91
40.19
27.67
100.00a.p.f.u.
Fe
Cu
Mg
Al
SiO4
SO4
UO2+
2
H2O

* H2O in wt.% was calculated based on the content of 11 H2O in the crystal structure of leydetite.

431

0.93
0.01
0.07
0.04
0.02
1.96
1.01
11.00

J. PLÁŠIL ET AL.

FIG. 2. Raman spectrum of leydetite.

Fe, two U and two S atoms. Lowering of symmetryof the tetrahedral SO4 groups may lead to theactivation of all modes in Raman and IR and also
to the splitting of the degenerate n2 (d), n3 and n4(d) vibrations. We observed an unusual splitting ofRaman bands attributed to the n1 symmetric UO2+
2

stretching mode, which may be explained in theway reported by Volod’ko et al. (1965) for sodium
uranyl acetate. Polarized Raman spectra andfactor-group analysis would be required to understand more fully the cause of the splitting, but thisis beyond the aim of the current paper.

FIG. 3. IR spectrum of leydetite.

432

LEYDETITE, A NEW URANYL SULFATE MINERAL

Raman bands at 3492, 3404, 3237 and3130 cm 1 and IR bands at 3526, 3461, 33376
and 3169 cm 1 are assigned to n(O H) stretchingvibrations of symmetrically non-equivalent H2O
molecules. According to Libowitzky’s correlation(Libowitzky, 1999), O H_O hydrogen-bondlengths, inferred from the frequencies of theobserved vibrational bands, vary approximately inthe range 2.82 2.69 Å. This range matchesclosely the values obtained from X-ray diffraction(~2.97 2.69 Å). The shoulder at 2927 cm 1 may
be caused by organic impurities. Infrared bands at
2362 and 2345 cm 1 are artefacts due toatmospheric CO2. Two Raman bands at 1679
and 1649 cm 1 and an IR band at 1641 cm 1 are
related to the n2(H O H) bending vibrations of
H2O molecules.
Raman bands at 1203, 1180, 1150, 1139, 1135,
1113 and 1099 cm 1 (1166 and 1104 cm 1 in IR)
are attributed to the split triply degenerate n3
antisymmetric stretching vibrations of SO4. Bands
at 1038, 1030, 1023 and 1015 cm 1 (1024 and1001 cm 1 in IR) are attributable to the n1
symmetric stretching vibrations of SO4 groups.
Raman bands at 937 and 930 cm 1 (in IR at
935 and 916 cm 1) are assigned to the n3
antisymmetric stretching vibrations of UO2+
2 andthose at 858, 851, 846, 843, 836 and 828 cm 1 ton1 symmetric stretching modes of UO2+
2 . In the IR
spectrum no band that may be attributed tosymmetric stretching of UO2+
was observed.
2
According to Bartlett and Cooney (1989), U O
bond lengths, inferred from the frequencies of
UO2+
2 stretching vibrations, vary in the range from1.75 to 1.78 Å (for IR, 1.76 and 1.77 Å). This
corresponds with those obtained from the present
structure determination.
Raman bands at 686, 675, 666 and 608 cm 1
(IR at 630 and 588 cm 1) are related to split triply
degenerate n4 (d) SO4 bending vibrations, andthose at 485, 464, 443 and 420 cm 1 (IR at 472
and 432 cm 1) to split doubly degenerate n1 (d)SO4 bending vibrations. The reason for theincreased number of observed Raman bands may

TABLE 2. Summary of data-collection conditions and reﬁnement parameters for leydetite.
Ideal structural formula
Unit-cell parameters (based on 6174 reflections)a, b, c (Å)
b (º)
V (Å3)Z
Temperature (K)Wavelength
Crystal dimensions (mm)Collection mode, frame width, count. time
Limiting y angles (º)
Limiting Miller indicesNo. of reflections measured
No. of unique reflections
No. of observed reflections (criterion)
Rint
Absorption correction (mm 1), Tmin/Tmax
F000

Fe[(UO2)(SO4)2](H2O)11
11.3203(3), 7.7293(2), 21.8145(8)102.402(3)1864.18(10)4293
MoKa, 0.71073 Å
0.4560.2260.05
o scans, 1.0º, 7 s
3.21 29.38
15 4 h 4 15, 10 4 k 4 10,
10504
8853
5211 [Iobs > 3s(I)]0.04039.76, 0.206/0.646
1358

Refinement by Jana2006 on F2Space group
Parameters refined, restraints, constraints
R1, wR2 (obs)
R1, wR2 (all)
GOF obs/all
Drmin, Drmax (e Å 3)
Weighting scheme

C2/c150, 10, 11
0.0224, 0.0238
0.0274, 0.0251
1.19/1.20
1.01, 1.51
w = 1/(s2(F) + 0.0001F2)

433

27 4 l 4 28

434

0.5
0
0.19154(8)-0.0777(3)0.4650(2)-0.1114(3)0.1222(3)0.6236(2)0.1344(3)0.8178(3)0.3064(2)0.1569(3)0.2146(3)0.5
0.779(5)0.460(5)0.844(5)–0.111(5)0.123(5)0.160(5)–0.091(5)–0.101(5)–0.185(4)0.124(5)0.192(4)0.20875(2)00.36898(11)0.2296(4)0.2066(3)–0.1552(5)0.2179(4)–0.0398(3)0.0165(5)0.2807(4)0.3136(3)0.4684(5)0.4834(4)0.5186(5)0.211(6)0.572(7)0.344(6)0.317(6)0.077(7)0.468(7)–0.185(6)0.239(7)–0.122(7)0.383(6)–0.043(7)

y/b
0.25
0
0.21074(4)0.02715(17)0.16723(13)0.04473(16)0.18393(15)0.25242(13)0.08208(16)0.12750(15)0.25264(14)0.03601(17)0.16201(14)0.250.144(2)0.266(2)0.155(2)0.002(2)0.108(2)0.073(2)0.085(2)0.061(2)0.039(2)0.021(2)0.091(2)z/c{reﬁned occupancy for the Fe atom is 0.981(4).
* reﬁned with Uiso = 1.2; *Ueq of the parent O atom.

U
Fe{
S
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11
H1
H2
H3
H4
H5
H6
H7
H8
H9
H10
H11

x/a
0.01487(6)0.0274(3)0.0191(3)0.0416(12)0.0240(9)0.0404(12)0.0339(11)0.0238(9)0.0431(12)0.0352(11)0.0273(9)0.0449(13)0.0332(10)0.0424(19)0.0422*0.0509*0.0422*0.05*
0.0517*
0.0539*0.0485*0.05*
0.0485*0.0539*0.0517*

Uiso/Ueq
0.01011(10)0.0332(5)0.0162(4)0.058(2)0.0233(14)0.043(2)0.0395(18)0.0171(13)0.046(2)0.042(2)0.0156(14)0.054(2)0.0401(18)0.038(3)U110.01244(10)0.0233(5)0.0150(4)0.0334(17)0.0263(15)0.0467(19)0.0283(16)0.0222(14)0.045(2)0.0335(18)0.0271(15)0.0353(19)0.0270(15)0.016(2)U220.02275(11)0.0259(5)0.0280(5)0.038(2)0.0230(14)0.0316(18)0.0358(17)0.0346(15)0.0334(19)0.0300(18)0.0414(17)0.042(2)0.0362(17)0.085(4)U33
00.0022(4)0.0018(4)0.0166(16)0.0026(12)0.0024(17)–0.0132(14)0.0059(11)0.0158(17)–0.0072(15)0.0067(11)–0.0119(16)0.0003(13)0U12TABLE 3. Atom positions and displacement parameters (Uiso/Ueq, in Å2) for leydetite.

0.00508(7)0.0069(4)0.0092(4)0.0211(17)0.0064(11)0.0083(16)0.0124(14)0.0116(11)–0.0020(16)0.0086(15)0.0113(12)0.0032(18)0.0164(13)0.040(2)U13

00.0004(3)0.0019(4)0.0041(15)0.0041(11)0.0110(15)–0.0086(13)0.0018(11)–0.0112(15)–0.0005(14)0.0054(12)–0.0002(16)0.0097(13)0U23J. PLÁŠIL ET AL.

LEYDETITE, A NEW URANYL SULFATE MINERAL[Iobs > 3s(I)]. Data were corrected for Lorentz,
polarization and background effects; a combinedcorrection, multi-scan and analytical (Clark andReid, 1997), for absorption effects was applied(CrysAlis RED, Agilent Technologies, 2012),
leading to Rint = 0.0403. A summary of the datacollection, crystallographic data and reﬁnement isgiven in Table 2.
The crystal structure of leydetite (Table 3) was
solved by the charge-ﬂipping algorithm implemented in the Superﬂip program (Palatinus andChapuis, 2007) and subsequently reﬁned using the
Jana2006 software (Petřı́ček et al., 2006) withfull-matrix least-squares reﬁnement based on F2.
The reﬂection conditions and statistics clearly
indicated the monoclinic space group C2/c. This
space group was also suggested by the Superﬂip
program, based on the symmetry operators
deduced from the ﬂipped electron density. All
atom types except hydrogen atoms were reﬁned
anisotropically. Hydrogen atoms were treatedusing soft constraints on bond lengths, 0.90 Å
with a constraint weight of (0.02), resulting in
D H lengths from 0.76(6) to 0.90(5) Å (Table 4),
and their isotropic displacement parameters were
set to 1.2Ueq of the parent (donor) O atoms. The
reﬁnement converged with the ﬁnal indices ofagreement R1 = 0.0224, wR2 = 0.0238 for 2159
observed reﬂections with GOF = 1.19. On thebasis of the reﬁned interatomic distances(Table 5), the bond-valence analysis (Table 6)
was performed following the procedure of Brown(1981, 2002).

be the same as for the case of SO4 stretchingvibrations, but some of these bands may also be
related to libration modes of H2O molecules.
Raman bands at 538, 522 and 504 cm 1 areassigned to n (U Oligand) stretching vibrations
and librations of H2O molecules. Raman bands at
394 and 373 cm 1 may be also attributed to the n(U Oligand) stretching vibrations, and Raman
bands at 290, 260, 236 and 223 cm 1 to split
doubly degenerate n2 (d) (UO2)2+ bending vibrations. Raman bands at 196, 182, 165, 138, 123,
116, 102, 89, 77 and 65 cm 1 are lattice modes.
Crystal structure of leydetite
Single-crystal X-ray diffraction
An untwinned fragment of leydetite, having
dimensions of 0.16 mm60.06 mm60.02 mm
was examined using an Oxford Diffraction
Gemini single-crystal diffractometer with an
Enhance-Mo collimator and Atlas CCD detector
using monochromatized MoKa radiation from asealed X-ray tube. The unit cell was reﬁned from5177 reﬂections by the least-squares algorithm of
the CrysalisPro package (Agilent Technologies,2012) giving a monoclinic cell with a =11.3203(3), b = 7.7293(2), c = 21.8145(8) Å,b = 102.402(3)º, V = 1864.18(10) Å3, and Z = 4.
Analysis of the diffraction frames after datacollection revealed no additional diffraction
peaks that might be present due to twinning.
From 8914 measured reﬂections, 2345 wereunique and 2159 were observed with the criterion

TABLE 4. Hydrogen-bond geometry (Å, º) in the crystal structure of leydetite.
Bondx

O7 H1_O10
O11 H2_O4xiii
O7 H3_O5xiv
O1 H4_O9vi
O6 H5_O4
O9 H6_O10
O3 H7_O2viii
O1 H8_O7v
O3 H9_O9viii
O9 H10_O3ii
O6 H11_O7viii

D H

H_A

D_A

D H_A angle

0.82(5)0.76(6)0.79(5)0.90(5)0.77(5)0.80(4)0.88(4)0.85(5)0.85(4)0.79(5)0.79(5)

1.98(5)
1.93(6)2.16(5)
1.88(5)
1.98(5)
1.91(4)
1.97(4)1.90(6)
1.91(5)2.25(5)2.01(5)2.755(5)2.687(4)2.912(4)2.760(5)2.741(5)2.688(5)2.835(4)2.732(6)2.759(5)2.973(5)2.780(5)

158(5)
172(5)
159(5)
166(4)
169(5)
163(6)
169(5)
168(5)
173(5)
151(6)
166(5)

Symmetry codes: (ii) x, y, z; (v) x 1, y, z; (vi) x,
x+1/2, y+1/2, z+1/2; (xiv) x+3/2, y+1/2, z+1/2.

y+1,

435

z; (viii) x 1/2, y 1/2, z; (x) x+1/2, y 1/2, z; (xiii)

J. PLÁŠIL ET AL.

TABLE 5. Selected interatomic distances (in Å) for
leydetite.
U O2
U O2i
U O5
U O5i
U O8
U O8i
U O11
<U Oeq>1.763(3)1.763(3)2.371(3)2.371(3)2.349(3)2.349(3)2.395(4)2.37
S O4
S O5iii
S O8
S O10
<S O>

Fe O1
Fe O1ii
Fe O3
Fe O3ii
Fe O6
Fe O6ii<Fe O>and S atoms, eleven distinct O atoms and elevendistinct H atoms in the asymmetric unit. The
crystal structure is based upon protasite anion
topology, with sheets of polyhedra containing
triangles and pentagons (Burns 2005). These
sheets arise from the linkage of uranyl pentagonal
bipyramids with sulfate tetrahedra via sharedvertices. Each pentagonal bipyramid is fourconnected within the sheet. At the free vertex of
the bipyramid, the H2O group extends hydrogenbonds (O11 H2_O4) towards one of the freevertices of the sulfate tetrahedron (Figs 4 and 5).
Sheets are parallel to {001}. In the interlayer,
Fe2+(H2O)6 octahedra and isolated H2O groups
are located. These link to one another and to thesheets on either side via a network of hydrogenbonds (Fig. 5).

2.121(4)2.121(4)2.124(4)2.124(4)2.089(3)2.089(3)2.11

1.458(3)1.488(3)1.482(3)1.449(3)1.47

Symmetry codes: (i) –x+1, y, –z+1/2; (ii) –x, –y, –z;(iii) x–1/2, y+1/2, z.

Powder X-ray diffraction

Description of the crystal structure
Structure solution and subsequent reﬁnement
proved that leydetite is isostructural with thesynthetic compound Mg(UO 2)(SO 4) 2(H2 O) 11
reported by Serezhkin et al. (1981). The current
structure model for leydetite contains reﬁned
positions of hydrogen atoms, which were notdetermined in the earlier structure determination
for the synthetic compound. The crystal structureof leydetite contains symmetrically unique U, Fe

Powder X-ray diffraction data for leydetite wereobtained using a Bruker D8 Discover powder
diffractometer equipped with a LynxEye detector
and a primary double-crystal Si monochromator
providing CuKa1 radiation. X-ray powder diffraction data are listed in Table 7. Positions ofdiffraction maxima were obtained by proﬁleﬁtting performed with Xﬁt software (Cheary and
Coelho, 1997). The unit cell was reﬁned with
Celref software (Laugier and Bochu, 2003). The
powder pattern of leydetite is strongly inﬂuenced
by the preferred orientation of the type (00l), which

TABLE 6. Bond-valence analysis for leydetite.
U
O1
O2
O3
O4
O5
O6
O7
O8
O9
O10
O11

S

Fe
0.3562;

H1

H2

H3

H4

H5

H6

H7

0.70

H8

H10

H11 SBV

1.79
1.97
0.3562;0.74 0.17
1.98
1.57
0.24
0.22
2.03
0.5462; 1.44
0.18
2.16
0.3862;0.81
0.79 1.98
0.78
0.79
0.24
0.22 2.07
0.5662; 1.47
2.03
0.25
0.78
0.24 0.79
2.04
1.60
0.22
0.24
2.06
0.52
0.82
2.14
6.21
6.08 2.16
1.00 1.06 0.97 0.95 1.03 1.02 0.95 0.98 0.98 0.96 1.01
1.7462;

0.74

H9

0.23
0.72

O
O
O
O
O
O
O
O
O
O
O

Values are expressed in valence units (v.u.). Multiplicity indicated by 62;. U6+ O bond strengths (r0 = 2.045, b =0.51) from Burns et al. (1997); S6+ O and Fe2+ O bond strengths from Brown and Altermatt (1985); H+ O bondstrengths after Brown (2002).

436

LEYDETITE, A NEW URANYL SULFATE MINERAL

FIG. 4. (a) The sheet and hydrogen bonding in the structure of leydetite. (b) Inﬁnite chains of polyhedra in the
structure of K2[(UO2)(SO4)2(H2O)](H2O) (Ling et al., 2010). The H bonds (in the case of the compound proposed by
Ling et al. (2010) only) are represented by dashed lines. The unit-cell edges are outlined.

FIG. 5. The structure of leydetite possessing sheets of uranyl pentagonal bipyramids (blue) and sulfate tetrahedra(yellow), stacked along {001}. Octahedra of composition Fe2+(H2O)6 (green) and an additional four H2O groups arelocated in the interlayer. Hydrogen bonds are displayed as dashed blue lines, hydrogen atoms as black circles.

437

J. PLÁŠIL ET AL.

TABLE 7. Powder X-ray diffraction data (dhkl in Å) for leydetite.
Iobs

Icalc

dobs

dcalc

h

k

l

Iobs

Icalc

dobs

dcalc

h

k

l

100.00
1.34
0.48
0.24
0.16
66.05
0.78
0.64
0.31
0.09
0.30
0.12
5.00
0.26
0.05
0.72
0.20
0.02
0.18
0.26
0.38
0.15
0.22
0.45
0.05
0.30
0.05
0.05
0.08
0.08
0.10
4.26
0.07
0.06
0.08
0.06
0.01

100
42
27
10
15
52
23
37
15
11
24
18
4
16
1
24
4
1
15
8
16
9
6
4
2
14
7
4
3
4
2
5
2
5
2
4
4

10.625
6.277
5.873
5.759
5.524
5.321
5.167
5.042
4.457
4.325
3.755
3.630
3.549
3.481
3.392
3.387
3.348
3.337
3.264
3.189
3.143
3.078
3.034
2.94562.91182.88462.82562.80842.76732.70642.70302.66312.62092.58582.54582.50812.404910.657
6.287
5.877
5.766
5.527
5.329
5.172
5.047
4.463
4.329
3.757
3.633
3.552
3.480
3.395
3.388
3.351
3.332
3.265
3.190
3.143
3.078
3.035
2.94742.91042.88672.82672.81022.76862.70682.70372.66442.62122.58622.54542.50902.4029

0
1̄
1
1̄
2
0
1
1̄
1
2̄
1̄
0
0
2
0
3̄
1
2̄
3̄
2̄
2̄
2
2̄
1
3̄
1̄
4̄
3
2
2̄
3̄
0
1
2
4
1
1̄

0
1
1
1
0
0
1
1
1
0
1
2
0
0
2
1
1
0
1
2
2
2
2
1
1
1
0
1
2
2
1
0
1
2
0
3
3

2
1
1
2
0
4
2
3
3
4
5
2
6
4
3
1
5
6
3
1
2
1
3
6
5
7
2
3
3
5
6
8
7
4
2
0
3

0.02
0.10
0.06
0.08
0.15
0.05
0.04
0.18
1.78
0.19
0.09
0.29
0.18
0.18
0.09
0.16
0.15
0.04
0.04
0.05
0.09
0.07
0.07
0.94
0.04
0.04
0.08
0.04
0.04
0.04
0.05
0.37
0.04
0.05
0.17
0.08
0.06

3
3
2
1
4
5
1
4
2
5
2
4
1
6
1
3
2
3
1
2
2
3
3
1
2
2
1
1
1
<1
1
1
1
1
<1
<1
<1

2.33052.31232.22892.22172.22012.16302.14942.13352.13092.12642.12082.11102.07672.0513
1.9493
1.91971.8852
1.87821.8705
1.86791.86491.7923
1.78391.7761
1.76561.76391.73661.6895
1.6373
1.61781.5942
1.52251.5042
1.44981.3324
1.1843
1.06602.33042.31382.23142.22232.2206
2.16272.14942.13382.13152.12572.11762.11132.07612.0513
1.94891.9203
1.88501.87871.86971.8664
1.8644
1.7922
1.78371.7762
1.7652
1.76391.7372
1.6893
1.63771.61731.5942
1.52251.50431.45001.3322
1.1842
1.0657

1
1̄
2
3
2
5̄
4̄
1
0
4
1
3
3
3̄
1
1̄
3
2̄
6̄
0
0
1
1
0
4
3̄
2
2
2̄
5
2
0
4
3̄
0
0
0

3
1
2
1
0
1
2
1
0
2
3
3
3
3
1
1
3
2
0
2
4
1
3
0
2
3
4
4
2
3
0
0
2
3
0
0
0

3
9
6
6
8
3
5
9
10
2
5
0
1
4
10
11
4
10
4
10
3
11
8
12
6
8
3
4
12
2
12
14
9
12
16
18
20

5 100º2y CuKa, step size 0.01º, counting time 4 s step 1, sample was rotated (frequency 0.5 s 1).

is caused by the excellent cleavage of the crystals.
Diffraction maxima were indexed in accordancewith the calculated values of intensities obtained
from the structure model and calculated by the
PowderCell program (Kraus and Nolze, 1996).
Reﬁned unit-cell parameters from the powder data
are given in Table 8.
Discussion
The structures of two synthetic uranyl sulfates are
based upon the same sheet topology as leydetite.
438

These are [(UO2)(SO4)2]H2(H2O)5 (Alcock et al.,1982) and K2[(UO2)(SO4)2](H2O)2 (Niinistö etal., 1979). The latter is particularly interesting inthat its possible occurrence in nature cannot be
excluded. We speculate that it may occur in acidenvironments with a high activity of K+, as does
adolfpateraite, K[(UO2)(SO4)(OH)(H2O)] (Plášil
et al., 2012b), particulary considering the similarvalue of the charge deﬁciency per anion(Schindler and Hawthorne, 2008) of the structuralunits of these two compounds. Interestingly, thebasic sheet motif in leydetite,LEYDETITE, A NEW URANYL SULFATE MINERALTABLE 8. Reﬁned unit-cell parameters for leydetite and for synthetic Mg(UO2)(SO4)2(H2O)11.

a
b
c
b
V

Leydetite, Mas d’Alary
Single-crystal; this study

Leydetite, Mas d’Alary
Powder; this study

Mg(UO2)(SO4)2(H2O)11
Single-crystal; Serezhkin et al. (1981)

11.3203(3)7.7293(2)21.8145(8)102.402(3)1864.18(10)11.319(3)7.723(1)21.826(3)102.41(2)1864.7(6)11.334(6)7.715(3)21.709(9)102.22(6)1855.3[(UO2)(SO4)2(H2O)]2 , is similar to that ofanother synthetic compound, K2[(UO2)(SO4)2(H2O)](H2O), prepared by Ling et al. (2010).
Sheet linkages are compared in Figs 4a and b. The
sheets are topological isomers of the sheet inleydetite (Fig. 4a) which is more highly polymerized than that in K2[(UO2)(SO4)2(H2O)](H2O), where the alternating up-downorientation of pentagonal bipyramids (Fig. 4b)
prevents the chains from polymerizing further toform sheets.The orientation of the tetrahedral
elements in the chain structure of K2[(UO2)(SO4)2(H 2O)](H 2O) also offers the possibility ofgeometrical isomerism.
Leydetite is known only from the type locality.
However, Plášil et al. (2012a) described an
unnamed mineral having a very similar chemicalcomposition from the L’Ecarpière mine, Gétigné,
Loire Atlantique, France. The unnamed phase wasfound to be the part of a deliensite sample,
forming crusts overgrown by deliensite. The
unnamed phase has the empirical formula:(Fe 0 . 7 1 Mg 0 . 2 0 Zn 0 . 0 8 Mn 0 . 0 2 ) S 1 . 0 1 (UO 2 ) 1 . 0 1[(SO4)1.98(SiO4)0.02]S2.00(H2O)n (calculated as themean of 5 point analysis on the basis of 2 S +Si a.p.f.u.). Based on this result we conclude that
this phase is equivalent to leydetite.
Acknowledgements
The authors thank Jean-Claude Leydet (Brest) for
providing us with the material for study. We also
thank Vincent Bourgoin for providing photomicrographs of leydetite samples. Referees Tony Kampf
and Igor Pekov are thanked for thorough reviews
that helped improve the manuscript. This work was
supported by the Premium Academiae and a grantof the Czech Science Foundation (P204/11/0809)
to MD, KF and JP. Further support was provided
by EU-project ‘‘Research group for radioactive
waste repository and nuclear safety’’ (CZ.1.07/

2.3.00/20.0052) to RŠ and MN, as well as a longterm project of the Ministry of Culture of the
Czech Republic (MK00002327201) to JČ.
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