Mineralogical Magazine, October 2012, Vol. 76(5), pp. 1119–1131

Ianbruceite, ideally [Zn2(OH)(H2O)(AsO4)](H2O)2, a newarsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto)region, Namibia: description and crystal structure
M. A. COOPER1, Y. A. ABDU1, N. A. BALL1, F. C. HAWTHORNE1,*, M. E. BACK2, K. T. TAIT2, J. SCHLÜTER3,
T. MALCHEREK3, D. POHL3 AND G. GEBHARD4
1

Department of Geological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
Department of Natural History (Mineralogy), Royal Ontario Museum, 100 Queen’s Park, Toronto,
Ontario M5S 2C6, Canada
3
Mineralogical-Petrological Institute, University of Hamburg, Grindelallee 48, D-20146 Hamburg, Germany
4Grobenseifen, 51545 Waldbröl, Germany
2[Received 20 February 2012; Accepted 2 July 2012; Associate Editor: Sergey Krivovichev]
ABSTRACT

Ianbruceite, ideally [Zn2(OH)(H2O)(AsO4)](H2O)2, is a new supergene mineral from the Tsumeb mine,
Otjikoto (Oshikoto) region, Namibia. It occurs as thin platy crystals up to 80 mm long and a few mm
thick, which form ﬂattened aggregates up to 0.10 mm across, and ellipsoidal aggregates up to 0.5 mm
across. It is associated with coarse white leiteite, dark blue köttigite, minor legrandite and adamite.
Ianbruceite is sky blue to very pale blue with a white streak and a vitreous lustre; it does not ﬂuoresce
under ultraviolet light. It has perfect cleavage parallel to (100), is ﬂexible, and deforms plastically. The
Mohs hardness is 1 and the calculated density is 3.197 g cm3. The refractive indices are a = 1.601, b =1.660, g = 1.662, all 0.002; 2Vobs = 18(2)º, 2Vcalc = 20º, and the dispersion is r < v, weak. Ianbruceite
is monoclinic, space group P21/c, a = 11.793(2), b = 9.1138(14), c = 6.8265(10) Å, b = 103.859(9)º, V= 712.3(3) Å3, Z = 4, a:b:c = 1.2940:1:0.7490. The seven strongest lines in the X-ray powder
diffraction pattern [d (Å), I, (hkl)] are as follows: 11.29, 100, (100); 2.922, 17, (130); 3.143, 15, (2̄02);
3.744, 11, (300); 2.655, 9, (230); 1.598, 8, (1̄52); 2.252, 7, (222). Chemical analysis by electron
microprobe gave As2O5 36.27, As2O3 1.26, Al2O3 0.37, ZnO 49.72, MnO 0.32, FeO 0.71, K2O 0.25,
H2Ocalc 19.89, sum 108.79 wt.%; the very high oxide sum is due to the fact that the calculated H2Ocontent is determined from crystal-structure analysis, but H2O is lost under vacuum in the electron
microprobe.
The crystal structure of ianbruceite was solved by direct methods and reﬁned to an R1 index of 8.6%.
The As is tetrahedrally coordinated by four O anions with a mean AsO distance of 1.687 Å. Zigzag[[5]Zn[6]Znj7] chains extend in the c direction and are linked in the b direction by sharing corners with
(AsO4) tetrahedra to form slabs with a composition [Zn2(OH)(H2O)(AsO4)]. The space between theseslabs is ﬁlled with disordered (H2O) groups and minor lone-pair stereoactive As3+. The ideal formuladerived from chemical analysis and crystal-structure solution and reﬁnement is[Zn2(OH)(H2O)(AsO4)](H2O)2.
K EY WORDS : ianbruceite, new mineral species, arsenate, Tsumeb mine, Otjikoto (Oshikoto) region, Namibia,
crystal structure, electron microprobe analysis, optical properties.

Introduction* E-mail: frank_hawthorne@umanitoba.ca
DOI: 10.1180/minmag.2012.076.5.05# 2012 The Mineralogical Society

THE Tsumeb mine in the Otjikoto (Oshikoto)region of Namibia is famous for the diversity andM. A. COOPER ET AL.

spectacular appearance of its minerals (Pinch andWilson, 1977), and was a major source of Cu-PbZn ores for most of the twentieth century. A pipelike structure of ‘pseudoaplite’ (Weber andWilson, 1977) intrudes a sequence of arkoses,
greywackes and dolomitic limestones; pods, lenses
and veins of sulﬁde occur at the periphery of thepipe in a matrix of disseminated ore. Extensiveoxidation zones were encountered between thesurface and 300 m and from ~8001450 m wherea fracture zone intersects the orebody (Weber andWilson, 1977). A wide variety of secondary
minerals (Pinch and Wilson, 1977) and exotic
parageneses (Keller, 1977) have been describedand new species continue to be discovered.
Ianbruceite was characterized independently byresearchers at the University of Manitoba and theRoyal Ontario Museum, Canada, and the
University of Hamburg, Germany. Data fromboth groups were combined at a late stage and arepresented here. In 1994, one of the authors (GG)
received a specimen of leiteite, overgrown by
dark blue crystals of köttigite and pale blue
crystals of an unknown phase, from the ‘Zinc
Pocket’ on the 44 level of Tsumeb mine. It was
described as a probable new species, using thecode GS17, and ﬁgured in Gebhard (1999: p.
296). Investigations of a specimen of GS17 in themineral collection of the Royal Ontario Museum
independently identiﬁed a new hydroxy-hydrated
zinc arsenate. It is named ianbruceite for Ian
Bruce (born 01/04/1969 at Okehampton, Devon,
England), a prime mover in the recent reopening
the Tsumeb mine for mineral collecting, who hasmade signiﬁcant contributions to the mineralcollections of many of the world’s major
museums through his professional activities. The
new mineral and mineral name have been
approved by the Commission on New Minerals,
Nomenclature and Classiﬁcation of theInternational Mineralogical Association (IMA
2011-49). The holotype specimen of ianbruceite
is registered in the mineral collection of the
Department of Natural History, Royal Ontario
Museum (catalogue number M53150) and holotype crystals are deposited in the collection of theMineralogical Museum of the University of
Hamburg, Grindelallee 48, D-20146 Hamburg,
Germany (catalogue number TS 119B).
Physical properties
Ianbruceite occurs as aggregates of thin ﬂakes
and tapered platy crystals up to 80 mm long and a

few mm thick, and as rounded ellipsoidal
aggregates up to 0.5 mm across. It is associatedwith coarse white leiteite, dark blue köttigite,
minor legrandite and adamite (Fig. 1). The
crystal forms are as follows: {100} dominant,{011} and {05̄1} prominent. It is sky blue tovery pale blue with a white streak and a vitreous
lustre, and does not ﬂuoresce under ultraviolet
light. The platy crystals have perfect cleavage
parallel to (100); no parting or twinning wasobserved. The Mohs hardness is 1. Ianbruceite is
ﬂexible and does not fracture but deforms
plastically. The calculated density is3.197 g cm3. Optical properties were measured
using a Bloss spindle stage at a wavelength of
590 nm (using a gel ﬁlter). The indices ofrefraction are a = 1.601, b = 1.660, g = 1.662,
all 0.002; 2Vobs = 18(2)º, 2Vcalc = 20º, and thedispersion is r < v, weak. No pleochroism wasobserved in the (100) plane, and the orientation
is as follows: X ^ a = 12.0º (in b obtuse), Y || b,Z ^ c = 4.7º (in b obtuse).
Raman spectroscopy
Spectra were collected in back-scattered mode on
a HORIBA Jobin Yvon-LabRAM ARAMIS
integrated confocal micro-Raman systemequipped with a 460 mm focal length spectrograph and a multichannel air-cooled (70ºC)

FIG. 1. Sky blue to blue crystal aggregates of platy,
tapered ianbruceite crystals with blue to deep blue
copper-bearing aggregates of köttigite on white leiteitefrom the Tsumeb mine, Tsumeb, Namibia. Width of theimage is 1.3 mm. Photo: K.-C. Lyncker, Hamburg.

1120

IANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEB

FIG. 2. (a,b) The Raman spectrum of ianbruceite; (c,d) the infrared spectrum of ianbruceite.

TABLE 1. Chemical composition of ianbruceite.
Constituent

Mean (wt.%)1

Range1

Mean (wt.%)2

Range2

As2O5
As2O3
Al2O3
ZnO
MnO
FeO
CaO
K2O
H2Ocalc
Total

36.27(1.07)
1.26
0.37(19)49.72(92)0.32(15)0.71(18)
0.25(4)19.893108.7935.7139.54

36.48

30.7842.20

0.170.90
48.2851.52
0.160.57
0.531.05

0.190.30


49.15


0.06

14.314100.00
48.2350.30

0.020.11

Elements that were sought but not detected: Cu, Na, Ca, Si, P, S, Mg, Ti, V, Cr, Ni, F, Cl.
Data gathered on a Cameca SX100 instrument at 15 kV, 10 nA, with a 5 mm beam diameter, mean of 10
determinations.
2
Data gathered on a Cameca SX100 instrument at 15 kV, 20 nA, with an ~1 mm beam diameter.
3
The H2O value calculated from structure reﬁnement.
4
The H2O value calculated by difference.
11121

M. A. COOPER ET AL.

CCD detector. A magniﬁcation of 1006 was usedwith an estimated spot size of 1 mm, a 1800 lines
mm1 grating, an excitation radiation of 532 nm,
and a laser power between 5 and 12.5 mW. The
spectrometer was calibrated using the 520.7 cm1line of silicon. The Raman spectrum is shown in
Fig. 2a,b. In the 1001200 cm1 region, there isa prominent peak at 840 cm1 that is assigned toAs5+O stretching vibrations. Peaks at 534, 448
and 420 cm1 are assigned to ZnO stretching
and bending vibrations of the (AsO4) groups; the192 cm 1 peak is a lattice mode. In the25004000 cm1 region, there is a broadenvelope centred on 3224 cm1 and weakshoulders at 3441 and 3224 cm1 that are
produced by H2O stretching vibrations. The
sharp peak at 3600 cm1 is an OH stretch.
The ﬁrst Raman spectrum of ianbruceite thatwas collected had peaks due to CH stretching;
the specimen had been immersed in alcohol andcontamination was suspected. This proved to be
the case as the Raman spectra of grains ofianbruceite that had not been immersed inalcohol did not have CH stretches (Fig. 2).
This suggests that the interstitial space in the
structure that is occupied by disordered (H2O)
groups can absorb alcohol.

Chemical composition
Crystals were analysed on two Cameca SX-100
electron microprobes operating in wavelengthdispersive mode in the conditions listed inTable 1. The data were reduced and correctedby the PAP method of Pouchou and Pichoir(1985) and the ZAF method. Raman spectra(Fig. 2) show a broad intense band in the region
25004000 cm1, which is indicative of (H2O),
and a sharp peak at 3600 cm1 indicative of (OH).
The quantity of (OH) and (H2O) groups in

TABLE 2. X-ray powder diffraction data for ianbruceite.
Iobs

Icalc*

dobs (Å)

dcalc* (Å)

h k l

100
2
11

100
1
9
<1
<1
25
<1
<1
2
1
14
7
<1
17
<1
4
9
<1
<1
6
<1
<1
2
3
<1
3
<1
<1
4
<1
<1
1
9
<1
<1
<1

11.29
4.549
3.744

11.290
4.571
3.764
3.759
3.718
3.194
3.179
3.106
3.016
2.987
2.942
2.839
2.823
2.682
2.618
2.501
2.407
2.368
2.363
2.259
2.258
2.240
2.054
1.895
1.892
1.817
1.815
1.814
1.698
1.695
1.691
1.649
1.609
1.601
1.600
1.597

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

15

17
7

Infrared spectroscopy
The Fourier transform infrared (FTIR) spectra
were collected using a Bruker Hyperion 2000 IR
microscope equipped with a liquid-nitrogencooled mercury-cadmium-telluride detector.
Spectra in the range 4000650 cm1 wereobtained by averaging 100 scans with a resolutionof 4 cm1. A very broad envelope centred at~3000 cm1 and sharp peaks at ~1600 and~1670 cm1 (Fig. 2c), are indicative of H2O
stretches and HOH bends, and indicate thepresence of considerable H2O in ianbruceite. Finestructure in the broad envelope, particularly in theregion around 3500 cm1, is indicative of thepresence of (OH), which is in accord with the
crystal structure reﬁnement. The strong peaks at
853, 838, 774 and 750 cm1 (Fig. 2d) are
assigned to As5+O stretching vibrations, theweak shoulder at ~690 cm1 is assigned to an
As3+O stretching vibration, and the weakshoulder at ~930 cm 1 to an As 3+ OH
bending vibration. The low intensity of thepeaks involving As3+ are in accord with thevery low occupancy (~0.04) of the sites
containing As3+.

9
1
5
7

2
2
4

8

3.143

2.922
2.819
2.655
2.480
2.381
2.252

1.890
1.804
1.692

1.598

* Calculated from the reﬁned crystal structure.

1122

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

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

IANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEBTABLE 3. Miscellaneous information for ianbruceite structure solutions and reﬁnements.
Parametera (Å)bcb (º)
V (Å3)
Space group
Z
Crystal size (mm)Radiation
No. of reflections
No. unique reflections
Rmerge (%)
Robs (%)

Refinement 1(Univ. of Manitoba)
11.793(2)9.1138(14)6.8265(10)103.859(9)712.3(3)P21/c
44064064
MoKa
10,229
1352
3.51
8.6

ianbruceite was determined by crystal-structure
reﬁnement and the resultant composition is listed
in Table 1 (column 2).
In ianbruceite, there are well-ordered (OH) and(H2O) groups that are associated with the Zn sitesof the [Zn2(OH)(H2O)(AsO4)] structural unit.
There are also two interstitial (H2O) groups witha large degree of positional disorder (i.e. large
anisotropic-displacement parameters). Some additional (minor) electron density was identiﬁed in
the difference-Fourier map ~1.7 Å from the (OH)group at O(4); we interpret this as belonging toAs3+ as part of an [As3+(OH)2O] group, with O(4)as the O ligand. Where the [As3+(OH)2O] group ispresent, one of the neighbouring interstitial (H2O)
sites must be vacant (as As3+_(H2O) is <2 Å).
If we initially disregard any contribution from[As 3+ (OH) 2 O] and normalize the chemical
formula to 8 anions [O4 + (OH) + (H2O)3],
there is a slight excess in the number of As5+
cations. If we then include minor [As3+(OH)2O]x
in the calculation (with x = 0.04), there is an
improvement in stoichiometry. The net formula
unit can be expressed in terms of the[As3+(OH)2O]x and [(OH)(H2O)](1x) contributions (where x = 0.04 for the crystal analysed byelectron microprobe). The resulting anion part of
the formula unit contains O4.04 + (OH)1.04 +(H2O)2.96 = 8.04 anions, and the chemicalcomposition normalized accordingly gives theempirical formula K 0.02 (Zn 1.93 Fe 2+
0.03 Al 0.02
M n 20 +. 0 1 ) S = 1 . 9 9 ( O H ) 0 . 9 6 ( H 2 O ) ( A s 5 + O 4 )[As 3+ (OH) 2 O] 0 .0 4 (H 2 O) 1.9 6 . The idealized
formula is [Zn2(OH)(H2O)(AsO4)](H2O)2. The(H2O) at the end of the formula is interstitial;

Refinement 2(Univ. of Hamburg)
11.612(7)9.142(5)6.793(3)103.52(4)701.1(7)P21/c
46065068
MoKa
6337
1381
9.9
12.4

this has signiﬁcant implications from a structural
viewpoint, which are discussed below.
The interstitial (H2O) in ianbruceite is not heldstrongly in the structure. The crystal grains
fracture extensively when exposed to the electron
beam in vacuum in an electron microprobe.
A comparison of the sum of the oxides and thecalculated H2O content shows that considerable
H2O is lost in this process. The loss of H2O results
in anomalously high values for the remaining
constituents, giving a high sum for the totaloxides (Table 2). The weakly bonded nature of
the interstitial (H2O) is apparent from two further
observations. The interstitial space between the[Zn2(OH)(H2O)(AsO4)] slabs can absorb alcohol,
as indicated by the Raman spectra, and preparation of material for powder diffraction resulted ina loss of interstitial (H2O), which is apparent if thea dimension derived from the single-crystal
diffraction study (11.793 Å) and that derived
from the powder diffraction study (11.583 Å) arecompared.
X-ray powder diffraction

1123

Powder-diffraction data are listed in Table 2. The
measured data were collected by the Hamburg
group on a Nonius kappa CCD four-circle
diffractometer in a Gandolﬁ-type arrangement
using MoKa radiation and the POWDERIZE
program. The calculated data were determinedusing JANA2000 (Petřı́ček and Dušek, 2000) fromthe single-crystal structure reﬁnement.
Additional powder-diffraction data werecollected by the Manitoba-Toronto group using

0.0129(10)0.0124(9)0.017(5)0.030(6)0.054(8)0.016(5)0.010(5)0.007(4)0.24(4)0.25(6)

As(1)
As(2)
As(3)
Zn(1)
Zn(2)
O(1)
O(2)=[H2O]
O(3)O(4)=(OH)O(5)O(6)O(7)=(H2O)
O(8)=(H2O)

0.36080(16) 0.91756(16) 0.0952(2)0.806(3)0.777(3)0.492(4)0.778(4)0.686(5)0.484(6)0.6179(2) 0.0413(2)0.4016(3)0.6059(2) 0.7591(2)0.1490(3)0.4319(11) 0.7571(11)0.0969(16)0.7964(10) 0.0882(14)0.5118(18)0.2201(11) 0.8861(13)0.081(2)0.6690(11) 0.8134(12)0.4307(15)0.4267(11) 0.0110(11)0.3102(15)0.3725(11) 0.0130(12) 0.1104(15)0.056(3)0.987(3)0.203(6)0.913(4)0.769(4)0.585(8)10.048(8)0.031(8)
1
1
1
1
1
1
1
1
0.96(8)0.91(9)0.0120(10)0.0198(10)0.015(5)0.045(8)0.020(6)0.011(5)0.012(5)0.023(6)0.11(3)0.13(4)0.0387(16)0.0398(16)0.020(7)0.009(7)0.022(7)0.048(8)0.048(8)0.038(8)0.10(3)0.11(3)

0.0005(6) 0.0083(9) 0.0015(8)0.0051(6) 0.0093(9) 0.0003(8)0.001(4)0.006(5)0.004(4)0.027(5) 0.003(5) 0.002(5)0.017(5)0.011(6) 0.002(5)0.006(4)0.011(5) 0.002(5)0.002(4)0.007(5) 0.000(5)0.004(4)0.006(5) 0.002(5)0.03(3)0.08(2)0.035(18)0.00(3)0.05(3)0.04(2)0.0004(6)0.0073(7)0.0008(5)0.0089(8)0.0380(13) 0.0106(8)

U13
y/b

z/c

Occupancy

U11

U22

U33

U23

U12

1124

x/a

All of the diffraction patterns showed extreme
streaking along a*. Very small crystals were used
to try to improve the data quality, and the crystalto-detector distance was increased to 8 cm to help
resolve the rather diffuse maxima within thestreaks. A small crystal which produced areasonably precise unit cell was eventuallyfound. It was attached to a tapered glass ﬁbre
and mounted on a Bruker D8 three-circle
diffractometer equipped with a rotating-anodegenerator (MoKa radiation), multilayer optics andan APEX-II detector. A total of 10,229 intensities(3233 within the Ewald sphere) were collected to
60º 2y using 40 s per 0.3º frame. Empiricalabsorption corrections (SADABS; Sheldrick,2008) were applied and equivalent reﬂections
were corrected for Lorentz, polarization andbackground effects, averaged and reduced tostructure factors. The unit-cell dimensions wereobtained by least-squares reﬁnement of thepositions of 4921 reﬂections with I > 10sI and
are given in Table 3, together with otherinformation pertaining to data collection andstructure reﬁnement.
All calculations were done with the SHELXTL
PC (Plus) system of programs; R indices are of
the form given in Table 3 and are expressed aspercentages. Systematic absences in the singlecrystal X-ray diffraction data are consistent withspace group P21/c, and the structure was solved
with this symmetry by direct methods and reﬁned
to convergence by full-matrix least-squares
techniques with anisotropic-displacement parameters on all atoms. At this stage, differenceFourier maps showed diffuse electron density inthe space (~4.7 Å wide) between adjacent layers
in the structure. Close inspection showed two
weak maxima ~1.7 Å from the O(4) anion. The
only constituent in the electron-microprobe
analysis that could possibly occur this close to
an O atom is As, and we included two additional

TABLE 4. Atom coordinates, occupancies and displacement parameters (Å2) for ianbruceite.

Crystal-structure solution and reﬁnement

Ueqa 114.6 mm diameter Gandolﬁ camera. The ﬁlm
was digitized using an optical scanner that wascalibrated for intensity and peak position using an
external Si standard, and the following unit-cellparameters were obtained by least-squares reﬁnement: a = 11.583(3), b = 9.159(2), c = 6.816(3) Å,b = 103.3(1)º and V = 703.7(3) Å3. Signiﬁcantinterstitial H2O was lost when this sample wasprepared for analysis, and as a result these data
are not listed.

0.0189(7)0.004(11)0.011(17)0.0208(8)0.0235(7)0.017(2)0.030(3)0.032(3)0.024(3)0.023(3)0.023(3)0.17(2)0.17(3)M. A. COOPER ET AL.

IANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEBTABLE 5. Selected interatomic distances (Å) and angles (º) in ianbruceite.

As(1)O(1)As(1)O(3)As(1)O(5)aAs(1)O(6)a<As(1)O>

1.685(10)1.664(13)1.714(10)1.684(10)1.687

Zn(1)O(1)f
Zn(1)O(2)Zn(1)O(4)b
Zn(1)O(5)Zn(1)O(5)c
Zn(1)O(6)d<Zn(1)O>

2.053(10)2.103(12)2.159(11)2.209(13)2.207(10)2.078(10)2.135

Partially occupied As sites
As(2)As(3)0.89(5)As(2)O(4)1.60(3)As(3)O(4)1.71(5)Structural (H2O)
O(2)_O(3)hO(2)_O(3)iO(3)hO(2)O(3)i

2.784(17)2.845(18)97.1(5)Interstitial (H2O)
O(7)_O(3)O(7)_O(8)for
O(7)_O(8)k
O(3)O(7)O(8)for
O(3)O(7)O(8)k

Zn(2)O(1)Zn(2)O(4)Zn(2)O(4)eZn(2)O(5)fZn(2)O(6)g<Zn(2)O>

1.997(12)1.952(11)1.934(10)2.322(10)2.117(11)2.064

Hydroxyl H-bondO(4)_O(8)2.84(4)

Interstitial (H2O)
O(8)_O(7)h2.69(5)O(8)_O(7)j
2.78(5)O(7)hO(8)O(7)j 120.2(1.5)

2.56(3)
2.69(5)2.78(5)95.3(1.3)
113.1(1.5)

Equivalent positions are as follows: a: x, y+1, z; b: x, y1, z; c: x̄ +1, ȳ, z̄+1; d: x̄+1, ȳ, z̄; e: x, ȳ+3/2, z; f: x̄+1,
y+,z̄+; g: x̄+1, ȳ +1, z̄; h: x̄+1, y,z̄ +; i: x̄+1, ȳ +1, z̄+1; j: x+1, y, z+1; k: x1, y, z1.

0.91(9), respectively. We consider the O(7) site tobe fully occupied by an (H2O) group. The O(8)site is located near (<2 Å) the As(2) and As(3)sites, and mutual occupancy of either As(2) orAs(3) by As3+ and the O(8) site by (H2O) is
unlikely. The combined occupancy of As3+ at
As(2) and As(3) is 0.079(16), and the reﬁned O(8)As sites with variable occupancy in the reﬁnement: As(2) and As(3), which were partly
occupied [1.6(3) and 1.0(3) e, respectively].
Two diffuse maxima within the interlayer wereidentiﬁed as disordered (H2O) groups, and assignment of the O scattering factor to the O(7) andO(8) sites gave reﬁned occupancies of 0.96(8) andTABLE 6. Bond-valence table (vu) for ianbruceite.

O(1)
O(2)
O(3)
O(4)

As(1)

Zn(1)

Zn(2)

S

1.25

0.39
0.34

0.45

0.29

0.51
0.54
0.19

2.09
0.34
1.32
1.34

1.32

O(5)

1.15

O(6)
O(7)
O(8)
S

1.25

0.26
0.26
0.36

0.33

H(1)

H(2)

H(3)

0.8
0.2

0.8
0.2

H(4)

H(5)

1.90

2.02

H(7)

S
2.09
1.94
1.92
2.14

0.2

0.8

1.86

1.86

1.94
0.8

4.97

H(6)

0.2
1.0

1.0

1.0

1.0

Bond-valence parameters in valence units (vu) from Brown and Altermatt (1985).

1125

0.8
0.2
1.0

0.2
0.8
1.0

0.2
0.8
1.0

1.94
2.00
2.00

M. A. COOPER ET AL.

site occupancy is 0.91(9), this is in accord with aformula containing As3+x and (H2O)1x, in which x~0.08. The structure reﬁnement converged to a
ﬁnal R1 index of 8.6%. The high R1 value is dueto the extreme stacking disorder along the a axis.
Reﬁned atom coordinates and anisotropic-displacement parameters are listed in Table 4, selectedinteratomic distances are given in Table 5, andbond valences, calculated using the parameters ofBrown and Altermatt (1985), are given in
Table 6.
A second dataset was collected on a Nonius
kappa CCD 4-circle diffractometer with MoKa
radiation; experimental details are given in
Table 3. A structural model was obtained using
Sir92 in space group P2 1/c. The structure
reﬁnement converged to a residual of 12.4% for
the observed reﬂections, with isotropic-displacement parameters for all oxygen atoms. The reﬁned
atom coordinates and interatomic distances are
similar to those listed in Tables 4 and 5.

= 2.135 and <[5]ZnO> = 2.064 Å, respectively.
The Zn(1) site is coordinated by O4(OH)(H2O)
and the Zn(2) site by O3(OH)2.
Structure topology

Crystal structure
Coordination of cations
In the structure of ianbruceite, As(1) is tetrahedrally coordinated with <AsO> = 1.687 Å,
which is typical of As5+ in tetrahedral coordination [e.g. adamite: 1.681 Å (Hawthorne, 1976a);scorodite: 1.680 Å (Hawthorne, 1976b)]. Zinc ispresent in two coordinations (Fig. 3), [6]-coordinated [octahedral: Zn(1)] and [5]-coordinated[triangular bipyramidal: Zn(2)], with <[6]ZnO>

The (Znj5) (j = O, OH, H2O) polyhedra share(OH) vertices to form [Znj4] chains that extend
in the c direction (Fig. 4, green). These [Znj4]
chains are decorated by (Znj6) octahedra (Fig. 4,blue), each of which shares edges with adjacent(Znj5) triangular bipyramids to form zigzag[[5] Zn [6]Znj7 ] chains that extend in the cdirection. These zigzag chains are linked in theb direction by sharing corners with (AsO4)
tetrahedra (Fig. 4, orange) to form sheets one
polyhedron thick in the a direction. Note that thepresence of tetrahedra and triangular bipyramids
imparts a polarity to this single-layer sheet. Twoof these sheets with opposite polarity link in the adirection by sharing edges between (Znj6)
octahedra and vertices between both Zn polyhedra
and As tetrahedra to form a structural unit ofcomposition [Zn2(OH)(H2O)(AsO4)]. This slab isshown face-on in Fig. 4 and edge-on in Fig. 5.
These [Zn 2(OH)(H2O)(AsO4)] slabs stackalong the a direction as shown in Fig. 5. The
separation of adjacent slabs is ~4.7 Å and two
positionally disordered (H2O) groups [O(7) andO(8)] occupy the interstitial space. The (H2O)
group associated with the (Znj6) octahedron, theO(3) vertex of the (AsO4) tetrahedron, and the(OH) group, are all situated at the margins of the

FIG. 3. The Zn polyhedra in ianbruceite; (a) the (Zn(1)O4(OH)(H2O)) octahedron (blue); (b) the (Zn(2)O3(OH)2)
trigonal bipyramid (green). The (OH) groups are shown as black circles and the (H2O) groups as red circles.

1126

IANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEB

FIG. 4. The crystal structure of ianbruceite projected onto (100), showing the connectivity of the[Zn2(OH)(H2O)(AsO4)] slab. The (Zn(1)O4(OH)(H2O)) octahedra are blue; (Zn(2)O3(OH)2) trigonal bipyramids
are green; (AsO4) groups are orange; (OH) groups are black circles; and (H2O) groups are red circles.

FIG. 5. The crystal structure of ianbruceite projected onto (010), showing the stacking of the [Zn2(OH)(H2O)(AsO4)]
slabs in the a direction. The (Zn(1)O4(OH)(H2O)) octahedra are blue; (Zn(2)O3(OH)2) trigonal bipyramids are green;(AsO4) groups are orange; (OH) groups are black circles; bonded (H2O) groups are small red circles; and interstitial(H2O) groups are large red circles.

1127

M. A. COOPER ET AL.

[Zn2(OH)(H2O)(AsO4)] slab and are involved inmutual hydrogen bonding with the interstitial(H2O) groups. The weakness of the inter-slab
bonding accounts for the extreme disorder in thestacking of the slabs (and the strong streaking
along a* observed in the diffraction pattern), andis consistent with the perfect {100} cleavage andthe ﬂexible but non-elastic behaviour of thin
ﬂakes of the mineral.
Anion identities and hydrogen bonding
There are eight crystallographically distinct
anions, O(1)O(8) (Table 4). Inspection of thebond-valence table (Table 6) shows that the bondvalence incident at O(2) is 0.34 vu and hence O(2)is an (H2O) group. The bond valence incident at
O(3) from As5+ alone is 1.32 vu and the O(3)anion receives bond valence from three additionalhydrogen bonds: two from neighbouring (H2O)
groups at O(2) along the surface of the[Zn2(OH)(H2O)(AsO4)] slab (Fig. 6) and one
from the interstitial (H 2 O) group at O(7)(Fig. 7). The O(4) anion bonds to three Zn
atoms and is an (OH) group; it directs a hydrogenbond toward the interstitial (H2O) group at O(8).
Additional mutual hydrogen bonding occurs
between the two interstitial (H2O) groups at
O(7) and O(8) (Table 6; Fig. 7).
We identiﬁed two partly occupied As sites,
As(2) and As(3) that are close together (Table 5)and cannot be occupied simultaneously. Thus
either of them will contribute bond valence to theadjacent O(4) anion. The sum of the bond valence
incident at O(4) from the cations of the structuralunit is 1.34 vu (Table 6), indicating that a further
bond valence of ~0.66 vu is needed to satisfy thevalence-sum rule. This value is too low for [4]As5+
but is typical for the short bonds of lone-pairstereoactive As3+, and hence we assign As3+ to
the As(2) and As(3) sites. Where As3+ is locallybonded to O(4), the latter is O2 in accord withthe local version of the valence-sum rule(Hawthorne, 1997). Electroneutrality requires
additional anions to neutralize the charge andcoordinate the interstitial As3+, these are two
additional (OH) groups forming an [As3+(OH)2O]
triangular pyramid with As3+ showing stereoactive lone-pair behaviour. The adjacent interstitial (H2O) group at O(8) is situated <2 Å from
As(2) and As(3), and this (H2O) group is locallyabsent if the [As3+(OH)2O] group is present.
Thus, if As3+ is absent, O(4) = (OH) and O(8) =(H2O); if As3+ is present, it is part of an

FIG. 6. The crystal structure of ianbruceite projected onto(100), showing hydrogen bonding along the surface ofthe [Zn2(OH)(H2O)(AsO4)] slab. The (Zn(1)O4(OH)(H2O)) octahedra are blue; (Zn(2)O3(OH)2) trigonal
bipyramids are green; (AsO4) groups are orange; (OH)groups are black circles and (H2O) groups are redcircles; and hydrogen bonds are shown as dashed lines
with arrows to the acceptor anions.

1128[As3+(OH)2O] group in which O(4) = O, two
additional (OH) groups are present, and O(8) =&. The net substitution is [As3+(OH)O(4)
O] +
2
O(8)
O(4)

O(8)
& $
(OH) +(H2O). We calculated[As3+(OH)2O]0.04 for the crystal analysed byelectron-microprobe and [As3+(OH)2O]0.08 forthe crystal analysed by structure reﬁnement.

IANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEB

FIG. 7. The crystal structure of ianbruceite projected down [001], showing the hydrogen bonding between the[Zn2(OH)(H2O)(AsO4)] slabs. The (Zn(1)O4(OH)(H2O)) octahedra are blue; (Zn(2)O3(OH)2) trigonal bipyramids aregreen; (AsO4) groups are orange; (OH) groups are black circles; (H2O) groups are small red circles; interstitial (H2O)
groups are large red circles; and hydrogen bonds are shown as dashed lines with arrows to the acceptor anions.

Related minerals
Ianbruceite is not isostructural with any othermineral. There are six other hydrated Zn-arsenate
minerals: koritnigite (Keller et al., 1980); köttigite(Hill, 1979); arsenohopeite (Neuhold, et al.,2012); davidlloydite (Hawthorne et al., 2012);
warikahnite (Riffel et al., 1980); and legrandite(McLean et al., 1971; Pushcharovskii et al.,1971), all of which occur at Tsumeb. Selected
properties of these minerals are listed in Table 7.
Koritnigite and köttigite have layer structures but
the layers are held together by hydrogen bonding
with no interstitial (H2O) groups. The only
difference between the formulae of legrandite
and ianbruceite is the two additional (H2O) groups
in ianbruceite. If the chemical formula ofeuchroite, Cu2+
2 (AsO4)(OH)(H2O)3, is comparedwith the formula of ianbruceite, it is easy to see
how ianbruceite could be mistakenly described as1129

a Zn analogue of euchroite. Both legrandite andeuchroite lack interstitial (H2O) groups and haveframework structures that are very different fromthe layer structure of ianbruceite. The different
roles of (H2O) in mineral structures are easily
indicated in formulae by separating the different
kinds of (H2O) groups, [i.e. those that bond to thestructural unit, and those that are interstitial(Hawthorne 1985, 1990, 1992)]. It is logical toplace (H2O) belonging to the structural unit in thatpart of the formula, following the cation(s) thatbond(s) to these (H2O) groups (i.e. after Zn for theminerals listed in Table 7); interstitial (H2O) is
placed outside the square brackets indicating thestructural unit, at the end of the formula. In thisway, the structural distinction between ianbruceite
and the other hydrated Zn-arsenates in Table 7(and euchroite) is conveyed by their chemical
formulae.

Zn(H2O)(AsO3OH)
1:1
Triclinic
P1̄
7.948
15.829
6.668
90.86
96.56
90.05
833.3
8
3.56
Layer
(open)
1.82

Koritnigite
Zn3(H2O)8(AsO4)2
3:2
Monoclinic
C2/m
10.24113.4054.757
90105.21
90
630.2
2
3.26
Layer
(open)
0.64

Köttigite* The minimum orthogonal distance across the interlayer, measured from oxygen centres.

Formula[Zn2(OH)(H2O)(AsO4)](H2O)2
Zn:As ratio
2:1
Symmetry
Monoclinic
Space groupP21/c
a (Å)
11.793
b
9.114
c
6.827
a (º)
90
b
103.86g
90712.3
V (Å3)Z
4
3.20
D (g cm3)
Structure type
Layer
Interlayer type(open; free H2O)Interlayer gap* (Å)
4.70

Ianbruceite
Zn3(H2O)4(AsO4)2
3:2
Orthorhombic
Pnma
10.80419.003
5.112
90
90
90
1049.54
3.46
Layer(octahedral bridge)


Arsenohopeite
Zn3(H2O)4(AsO4)2
3:2
Triclinic
P1̄
5.976
7.600
5.447
84.29
90.49
88.00
246.0
1
3.66
Layer
(octahedral bridge)Davidlloydite

TABLE 7. Comparative data for hydrated zinc arsenates.

Zn3(H2O)2(AsO4)2
3:2
Triclinic
P1̄
6.710
8.989
14.533105.5993.44
108.68789.5
4
4.29
Framework

Warikahnite

Zn2(OH)(H2O)(AsO4)
2:1
Monoclinic
P21/c
12.805
7.933
10.21590104.39901005.1
8
4.03
FrameworkLegranditeIANBRUCEITE, A NEW SUPERGENE MINERAL FROM TSUMEB

Acknowledgements
We thank Tony Steede of the Royal Ontario
Museum for his help with SEM and XRD work on
both ianbruceite and davidlloydite, the Louise
Hawley Stone Charitable Trust for acquisition of
the Charles Key mineral collection, and Tony
Kampf and an anonymous reviewer for theircomments on the manuscript. This work was
supported by a Canada Research Chair in
Crystallography and Mineralogy and by Natural
Sciences and Engineering Research Council of
Canada Discovery, Equipment and Major
Installation grants of the Natural Sciences andEngineering Research Council of Canada, and by
Innovation grants from the Canada Foundation for
Innovation to FCH.
References
Brown, I.D. and Altermatt, D. (1985) Bond-valence
parameters obtained from a systematic analysis of
the inorganic crystal structure database. Acta
Crystallographica, B41, 244247.
Gebhard, G. (1999) Tsumeb  A Unique Mineral
Locality. GG Publishing, Grossenseifen, Germany.
Hawthorne, F.C. (1976a) Reﬁnement of the crystal
structure of adamite. The Canadian Mineralogist, 14,143148.
Hawthorne, F.C. (1976b) The hydrogen positions inscorodite. Acta Crystallographica, B32, 28912892.
Hawthorne, F.C. (1985) Towards a structural classiﬁcation of minerals: The VIMIVT2jn minerals. American
Mineralogist, 70, 455473.
Hawthorne, F.C. (1990) Structural hierarchy in[6]
M [ 4 ] T j n m i n e r a l s . Z e i t s c h r i f t f ü r
Kristallographie, 192, 152.
Hawthorne, F.C. (1992) The role of OH and H2O inoxide and oxysalt minerals. Zeitschrift für
Kristallographie, 201, 183206.
Hawthorne, F.C. (1997) Short-range order in amphiboles: a bond-valence approach. The Canadian
Mineralogist, 35, 201216.
Hawthorne, F.C., Cooper, M.A., Abdu, Y.A., Ball ,N.A., Back, M.E. and Tait, K.T. (2012)
Davidlloydite, ideally Zn3(AsO4)2(H2O)4, a newarsenate mineral from the Tsumeb mine, Otjikoto(Oshikoto) region, Namibia: description and crystal
structure. Mineralogical Magazine, 77, 4557.
Hill, R.J. (1979) The crystal structure of köttigite.
American Mineralogist, 64, 376382.
Keller, P. (1977) Tsumeb VI. Paragenesis.
Mineralogical Record, 8(3), 3847.
Keller, P., Hess, H. and Riffel, H. (1980) Die
K ri st a ll st r ukt u r v on Kor it n ig it Z n( (H 2 O)
(OH)(AsO3)). Neues Jahrbuch für Mineralogie
Abhandlungen, 138, 316332.
McLean, W.J., Anthony, J.W., Finney, J.J. and Laughon,
R.B. (1971) The crystal structure of legrandite.
American Mineralogist, 56, 11471154.
Neuhold, F., Kolitsch, U., Bernhardt, H.-J. andLengauer, C.L. (2011) Arsenohopeite, a new zincarsenate mineral from the Tsumeb mine, Namibia.
Mineralogical Magazine, 76, 603612.
Petřı́ček, V. and Dušek, M. (2000) Jana 98 The
Crystallographic Computing System. Institute ofPhysics, Academy of Sciences of the Czech
Republic, Praha.
Pinch. W.W. and Wilson, W.E. (1977) Tsumeb V.
Minerals: a descriptive list. Mineralogical Record,
8(3), 1737.
Pouchou, J.L. and Pichoir, F. (1985) ‘PAP’ j(rZ)procedure for improved quantitative microanalysis.
Pp. 104106 in: Microbeam Analysis (J.T.
Armstrong, editor). San Francisco Press, San
Francisco, California, USA.
Pushcharovskii, D.Yu., Pobedimskaya, E.A. and Belov,
N.V. (1971) The crystal structure of legrandite
Zn 2 (AsO 4 )OH(H 2 O). Doklady Akademii Nauk
SSSR, 198, 10721075.
Riffel, H., Keller, P. and Hess, H. (1980) Die
Kristallstruktur von Warikahnit, Zn3((H2O)2(AsO4)2).
Tschermaks Mineralogische und Petrographische
Mitteilungen, 27, 187199.
Sheldrick, G.M. (2008) A short history of SHELX. Acta
Crystallographica, A64, 112122.
Weber, D. and Wilson, W.E. (1977) Tsumeb IV.
Geology. Mineralogical Record, 8(3), 1416.

1131

data_test2_audit_creation_method_chemical_name_systematic;?
;_chemical_name_common_chemical_melting_point_chemical_formula_moiety_chemical_formula_sum'H3 As O9 Zn2'_chemical_formula_weight

SHELXL-97?
?
?
352.68loop__atom_type_symbol_atom_type_description_atom_type_scat_dispersion_real_atom_type_scat_dispersion_imag_atom_type_scat_source'O' 'O'
0.01060.0060'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4''H' 'H'
0.00000.0000'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4''Zn' 'Zn'
0.28391.4301'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4''As' 'As'
0.04992.0058'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4'_symmetry_cell_setting_symmetry_space_group_name_H-M

?
?

loop_
_symmetry_equiv_pos_as_xyz'x, y, z''-x, y+1/2, -z+1/2''-x, -y, -z''x, -y-1/2, z-1/2'_cell_length_a_cell_length_b_cell_length_c_cell_angle_alpha_cell_angle_beta_cell_angle_gamma_cell_volume_cell_formula_units_Z_cell_measurement_temperature_cell_measurement_reflns_used_cell_measurement_theta_min_cell_measurement_theta_max

11.793(2)9.1138(14)6.8265(10)90.00
103.859(9)90.00
712.35(19)4293(2)?
?
?

_exptl_crystal_description_exptl_crystal_colour_exptl_crystal_size_max_exptl_crystal_size_mid

?
?
?
?

_exptl_crystal_size_min_exptl_crystal_density_meas_exptl_crystal_density_diffrn_exptl_crystal_density_method_exptl_crystal_F_000_exptl_absorpt_coefficient_mu_exptl_absorpt_correction_type_exptl_absorpt_correction_T_min_exptl_absorpt_correction_T_max_exptl_absorpt_process_details

?
?
3.289
'not measured'672
11.362?
?
?
?

_exptl_special_details;?
;_diffrn_ambient_temperature_diffrn_radiation_wavelength_diffrn_radiation_type_diffrn_radiation_source_diffrn_radiation_monochromator_diffrn_measurement_device_type_diffrn_measurement_method_diffrn_detector_area_resol_mean_diffrn_standards_number_diffrn_standards_interval_count_diffrn_standards_interval_time_diffrn_standards_decay_%_diffrn_reflns_number_diffrn_reflns_av_R_equivalents_diffrn_reflns_av_sigmaI/netI_diffrn_reflns_limit_h_min_diffrn_reflns_limit_h_max_diffrn_reflns_limit_k_min_diffrn_reflns_limit_k_max_diffrn_reflns_limit_l_min_diffrn_reflns_limit_l_max_diffrn_reflns_theta_min_diffrn_reflns_theta_max_reflns_number_total_reflns_number_gt_reflns_threshold_expression

293(2)
0.71073
MoK\a'fine-focus sealed tube'
graphite
?
?
?
?
?
?
?
3233
0.03510.0478
-14
12
-11
9
-8
8
1.78
26.46
1352
1106
>2sigma(I)_computing_data_collection_computing_cell_refinement_computing_data_reduction_computing_structure_solution_computing_structure_refinement_computing_molecular_graphics_computing_publication_material?
?
?
'SHELXS-97 (Sheldrick, 1990)''SHELXL-97 (Sheldrick, 1997)'?
?

_refine_special_details;
Refinement of F^2^ against ALL reflections. The weighted R-factor wR andgoodness of fit S are based on F^2^, conventional R-factors R are basedon F, with F set to zero for negative F^2^. The threshold expression ofF^2^ > 2sigma(F^2^) is used only for calculating R-factors(gt) etc. and isnot relevant to the choice of reflections for refinement. R-factors basedon F^2^ are statistically about twice as large as those based on F, and Rfactors based on ALL data will be even larger.
;_refine_ls_structure_factor_coef Fsqd
_refine_ls_matrix_type
full_refine_ls_weighting_scheme
calc_refine_ls_weighting_details'calc w=1/[\s^2^(Fo^2^)+(0.1108P)^2^+37.8672P] where P=(Fo^2^+2Fc^2^)/3'_atom_sites_solution_primary
direct_atom_sites_solution_secondary
difmap_atom_sites_solution_hydrogens
geom_refine_ls_hydrogen_treatment
mixed_refine_ls_extinction_method
SHELXL_refine_ls_extinction_coef
0.016(2)_refine_ls_extinction_expression'Fc^*^=kFc[1+0.001xFc^2^\l^3^/sin(2\q)]^-1/4^'_refine_ls_number_reflns
1352_refine_ls_number_parameters
114_refine_ls_number_restraints0_refine_ls_R_factor_all
0.1054_refine_ls_R_factor_gt
0.0863_refine_ls_wR_factor_ref
0.2344_refine_ls_wR_factor_gt
0.2213_refine_ls_goodness_of_fit_ref
1.106_refine_ls_restrained_S_all
1.106_refine_ls_shift/su_max
0.000_refine_ls_shift/su_mean
0.000
loop_
_atom_site_label_atom_site_type_symbol_atom_site_fract_x_atom_site_fract_y_atom_site_fract_z_atom_site_U_iso_or_equiv_atom_site_adp_type_atom_site_occupancy_atom_site_symmetry_multiplicity_atom_site_calc_flag_atom_site_refinement_flags_atom_site_disorder_assembly_atom_site_disorder_groupAs As 0.36080(16) 0.91756(16) 0.0952(2) 0.0189(6) Uani 1 1 d . . .
Zn1 Zn 0.6179(2) 0.0413(2) 0.4016(3) 0.0208(8) Uani 0.958(10) 1 d P . .
Zn2 Zn 0.6059(2) 0.7591(2) 0.1490(3) 0.0235(7) Uani 1 1 d . . .
O1 O 0.4319(11) 0.7571(11) 0.0969(16) 0.017(2) Uani 1 1 d . . .
O2 O 0.7964(10) 0.0882(14) 0.5118(17) 0.030(3) Uani 1 1 d . . .
O3 O 0.2201(11) 0.8861(13) 0.081(2) 0.032(3) Uani 1 1 d . . .
O4 O 0.6690(11) 0.8134(12) 0.4307(15) 0.024(3) Uani 1 1 d . . .
O5 O 0.4267(11) 0.0110(11) 0.3102(15) 0.023(3) Uani 1 1 d . . .
O6 O 0.3725(11) 0.0130(12) -0.1104(15) 0.023(3) Uani 1 1 d . . .
As2 As 0.806(3) 0.777(3) 0.492(4) 0.004(11) Uiso 0.048(8) 1 d P . .
As3 As 0.778(4) 0.686(5) 0.484(6) 0.011(17) Uiso 0.031(8) 1 d P . .
O7 O 0.056(3) 0.987(3) -0.203(6) 0.17(2) Uani 0.96(8) 1 d P . .
O8 O 0.913(4) 0.769(4) 0.585(8) 0.18(3) Uani 0.91(9) 1 d P . .

loop__atom_site_aniso_label_atom_site_aniso_U_11_atom_site_aniso_U_22_atom_site_aniso_U_33_atom_site_aniso_U_23_atom_site_aniso_U_13_atom_site_aniso_U_12
As 0.0380(13) 0.0106(8) 0.0089(8) -0.0008(5) 0.0073(7) 0.0004(6)Zn1 0.0387(16) 0.0120(10) 0.0129(10) -0.0005(6) 0.0083(9) 0.0015(8)Zn2 0.0398(15) 0.0198(10) 0.0124(9) -0.0051(6) 0.0093(9) -0.0003(8)O1 0.020(7) 0.015(5) 0.017(5) 0.001(4) 0.006(5) 0.004(4)O2 0.009(7) 0.045(8) 0.030(6) 0.027(5) -0.003(5) -0.002(5)O3 0.022(7) 0.020(6) 0.054(8) -0.017(5) 0.011(6) -0.002(5)O4 0.048(8) 0.011(5) 0.016(5) 0.006(4) 0.011(5) -0.002(5)O5 0.048(8) 0.012(5) 0.010(4) -0.002(4) 0.007(5) 0.000(5)O6 0.038(8) 0.023(6) 0.007(4) 0.004(4) 0.006(5) -0.002(5)O7 0.10(3) 0.11(3) 0.24(4) -0.03(3) -0.08(2) 0.035(18)O8 0.11(3) 0.13(4) 0.25(6) 0.00(3) -0.05(3) -0.04(2)_geom_special_details;
All esds (except the esd in the dihedral angle between two l.s. planes)
are estimated using the full covariance matrix. The cell esds are taken
into account individually in the estimation of esds in distances, angles
and torsion angles; correlations between esds in cell parameters are onlyused when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell esds is used for estimating esds involving l.s. planes.
;
loop__geom_bond_atom_site_label_1_geom_bond_atom_site_label_2_geom_bond_distance_geom_bond_site_symmetry_2_geom_bond_publ_flag
As O3 1.664(13) . ?
As O6 1.684(10) 1_565 ?
As O1 1.684(10) . ?
As O5 1.714(10) 1_565 ?
As As3 2.92(5) 2_655 ?
As O2 3.512(12) 2_655 ?
As O2 3.609(12) 3_666 ?
As O4 3.625(11) 2_655 ?
Zn1 O1 2.053(10) 2_645 ?
Zn1 O6 2.078(10) 3_655 ?
Zn1 O2 2.103(12) . ?
Zn1 O4 2.159(11) 1_545 ?
Zn1 O5 2.207(10) 3_656 ?
Zn1 O5 2.209(13) . ?
Zn1 Zn2 3.081(2) 1_545 ?
Zn2 O4 1.934(10) 4_575 ?
Zn2 O4 1.952(11) . ?
Zn2 O1 1.997(12) . ?
Zn2 O6 2.117(11) 3_665 ?
Zn2 O5 2.322(10) 2_655 ?

Zn2 As3 2.60(5) 4_575 ?
Zn2 As3 2.75(5) . ?
Zn2 As2 2.83(3) 4_575 ?
Zn2 As2 2.90(3) . ?
Zn2 Zn1 3.081(2) 1_565 ?
O1 Zn1 2.053(10) 2_655 ?
O1 O2 3.035(17) 2_655 ?
O2 O3 2.784(17) 2_645 ?
O2 O3 2.845(18) 3_666 ?
O2 As2 2.85(3) 1_545 ?
O2 O4 2.905(17) 1_545 ?
O2 O1 3.035(16) 2_645 ?
O2 O7 3.12(5) 3_665 ?
O2 O6 3.117(16) 3_655 ?
O2 As 3.512(12) 2_645 ?
O2 As 3.609(12) 3_666 ?
O2 As3 3.68(5) 1_545 ?
O3 O2 2.784(17) 2_655 ?
O3 O2 2.845(18) 3_666 ?
O4 As2 1.60(3) . ?
O4 As3 1.71(5) . ?
O4 Zn2 1.934(10) 4_576 ?
O4 Zn1 2.159(11) 1_565 ?
O4 O6 2.648(14) 3_665 ?
O4 O5 2.814(15) 3_666 ?
O4 O8 2.84(4) . ?
O4 O2 2.905(17) 1_565 ?
O4 O6 3.086(15) 2_655 ?
O4 As3 3.59(4) 4_575 ?
O4 O4 3.603(7) 4_575 ?
O5 As 1.714(10) 1_545 ?
O5 Zn1 2.207(10) 3_656 ?
O5 Zn2 2.322(10) 2_645 ?
O5 O4 2.814(15) 3_666 ?
O6 As 1.684(10) 1_545 ?
O6 Zn1 2.078(10) 3_655 ?
O6 Zn2 2.117(11) 3_665 ?
O6 O4 2.648(14) 3_665 ?
O6 O4 3.086(15) 2_645 ?
O6 O2 3.117(16) 3_655 ?
As2 As3 0.89(5) . ?
As2 O8 1.27(5) . ?
As2 Zn2 2.83(3) 4_576 ?
As2 O2 2.85(3) 1_565 ?
As3 O8 1.75(6) . ?
As3 Zn2 2.60(5) 4_576 ?
As3 As 2.92(5) 2_645 ?
As3 O4 3.59(4) 4_576 ?
As3 O2 3.68(5) 1_565 ?
As3 O4 3.68(4) 4_575 ?
O7 O2 3.12(5) 3_665 ?
loop__geom_angle_atom_site_label_1_geom_angle_atom_site_label_2_geom_angle_atom_site_label_3_geom_angle

_geom_angle_site_symmetry_1_geom_angle_site_symmetry_3_geom_angle_publ_flag
O3 As O6 108.6(6) . 1_565 ?
O3 As O1 109.8(6) . . ?
O6 As O1 108.3(5) 1_565 . ?
O3 As O5 112.2(6) . 1_565 ?
O6 As O5 110.3(5) 1_565 1_565 ?
O1 As O5 107.6(6) . 1_565 ?
O3 As As3 68.0(10) . 2_655 ?
O6 As As3 64.4(9) 1_565 2_655 ?
O1 As As3 169.9(9) . 2_655 ?
O5 As As3 82.0(10) 1_565 2_655 ?
O3 As O2 51.0(4) . 2_655 ?
O6 As O2 114.4(4) 1_565 2_655 ?
O1 As O2 59.8(4) . 2_655 ?
O5 As O2 135.3(4) 1_565 2_655 ?
As3 As O2 115.6(10) 2_655 2_655 ?
O3 As O2 50.1(5) . 3_666 ?
O6 As O2 141.8(4) 1_565 3_666 ?
O1 As O2 109.0(4) . 3_666 ?
O5 As O2 65.1(4) 1_565 3_666 ?
As3 As O2 77.5(9) 2_655 3_666 ?
O2 As O2 78.6(3) 2_655 3_666 ?
O3 As O4 94.9(4) . 2_655 ?
O6 As O4 58.1(4) 1_565 2_655 ?
O1 As O4 155.1(5) . 2_655 ?
O5 As O4 64.3(4) 1_565 2_655 ?
As3 As O4 27.7(10) 2_655 2_655 ?
O2 As O4 143.2(3) 2_655 2_655 ?
O2 As O4 89.4(3) 3_666 2_655 ?
O1 Zn1 O6 108.3(4) 2_645 3_655 ?
O1 Zn1 O2 93.8(5) 2_645 . ?
O6 Zn1 O2 96.4(5) 3_655 . ?
O1 Zn1 O4 174.3(4) 2_645 1_545 ?
O6 Zn1 O4 77.3(4) 3_655 1_545 ?
O2 Zn1 O4 85.9(5) . 1_545 ?
O1 Zn1 O5 94.2(4) 2_645 3_656 ?
O6 Zn1 O5 151.7(4) 3_655 3_656 ?
O2 Zn1 O5 99.0(5) . 3_656 ?
O4 Zn1 O5 80.3(4) 1_545 3_656 ?
O1 Zn1 O5 81.2(4) 2_645 . ?
O6 Zn1 O5 89.2(4) 3_655 . ?
O2 Zn1 O5 173.5(5) . . ?
O4 Zn1 O5 98.6(4) 1_545 . ?
O5 Zn1 O5 77.3(4) 3_656 . ?
O1 Zn1 Zn2 145.8(3) 2_645 1_545 ?
O6 Zn1 Zn2 43.2(3) 3_655 1_545 ?
O2 Zn1 Zn2 106.1(4) . 1_545 ?
O4 Zn1 Zn2 39.0(3) 1_545 1_545 ?
O5 Zn1 Zn2 109.3(3) 3_656 1_545 ?
O5 Zn1 Zn2 80.2(3) . 1_545 ?
O4 Zn2 O4 136.0(7) 4_575 . ?
O4 Zn2 O1 115.3(5) 4_575 . ?
O4 Zn2 O1 108.1(5) . . ?
O4 Zn2 O6 99.2(4) 4_575 3_665 ?
O4 Zn2 O6 81.1(4) . 3_665 ?

O1 Zn2 O6 97.8(4) . 3_665 ?
O4 Zn2 O5 82.2(4) 4_575 2_655 ?
O4 Zn2 O5 99.4(4) . 2_655 ?
O1 Zn2 O5 79.6(4) . 2_655 ?
O6 Zn2 O5 177.4(5) 3_665 2_655 ?
O4 Zn2 As3 41.1(11) 4_575 4_575 ?
O4 Zn2 As3 103.1(11) . 4_575 ?
O1 Zn2 As3 143.2(11) . 4_575 ?
O6 Zn2 As3 68.0(11) 3_665 4_575 ?
O5 Zn2 As3 114.2(11) 2_655 4_575 ?
O4 Zn2 As3 102.3(10) 4_575 . ?
O4 Zn2 As3 38.0(10) . . ?
O1 Zn2 As3 132.0(10) . . ?
O6 Zn2 As3 104.8(11) 3_665 . ?
O5 Zn2 As3 76.9(11) 2_655 . ?
As3 Zn2 As3 84.8(15) 4_575 . ?
O4 Zn2 As2 33.0(7) 4_575 4_575 ?
O4 Zn2 As2 104.2(7) . 4_575 ?
O1 Zn2 As2 147.6(6) . 4_575 ?
O6 Zn2 As2 86.0(6) 3_665 4_575 ?
O5 Zn2 As2 96.3(6) 2_655 4_575 ?
As3 Zn2 As2 18.1(11) 4_575 4_575 ?
As3 Zn2 As2 76.7(11) . 4_575 ?
O4 Zn2 As2 104.6(6) 4_575 . ?
O4 Zn2 As2 31.5(6) . . ?
O1 Zn2 As2 138.2(6) . . ?
O6 Zn2 As2 87.0(6) 3_665 . ?
O5 Zn2 As2 94.7(6) 2_655 . ?
As3 Zn2 As2 76.8(11) 4_575 . ?
As3 Zn2 As2 17.8(10) . . ?
As2 Zn2 As2 73.9(7) 4_575 . ?
O4 Zn2 Zn1 137.9(3) 4_575 1_565 ?
O4 Zn2 Zn1 44.1(3) . 1_565 ?
O1 Zn2 Zn1 90.9(3) . 1_565 ?
O6 Zn2 Zn1 42.3(3) 3_665 1_565 ?
O5 Zn2 Zn1 137.1(3) 2_655 1_565 ?
As3 Zn2 Zn1 98.4(10) 4_575 1_565 ?
As3 Zn2 Zn1 79.2(10) . 1_565 ?
As2 Zn2 Zn1 112.1(5) 4_575 1_565 ?
As2 Zn2 Zn1 65.4(5) . 1_565 ?
As O1 Zn2 118.8(6) . . ?
As O1 Zn1 133.6(7) . 2_655 ?
Zn2 O1 Zn1 106.9(5) . 2_655 ?
As O1 O2 91.6(5) . 2_655 ?
Zn2 O1 O2 149.5(5) . 2_655 ?
Zn1 O1 O2 43.7(3) 2_655 2_655 ?
Zn1 O2 O3 96.2(5) . 2_645 ?
Zn1 O2 O3 94.0(5) . 3_666 ?
O3 O2 O3 97.1(5) 2_645 3_666 ?
Zn1 O2 As2 80.1(7) . 1_545 ?
O3 O2 As2 164.5(8) 2_645 1_545 ?
O3 O2 As2 98.1(6) 3_666 1_545 ?
Zn1 O2 O4 47.8(4) . 1_545 ?
O3 O2 O4 142.5(6) 2_645 1_545 ?
O3 O2 O4 96.0(4) 3_666 1_545 ?
As2 O2 O4 32.4(7) 1_545 1_545 ?
Zn1 O2 O1 42.4(3) . 2_645 ?

O3 O2 O1 56.0(4) 2_645 2_645 ?
O3 O2 O1 86.1(5) 3_666 2_645 ?
As2 O2 O1 122.5(8) 1_545 2_645 ?
O4 O2 O1 90.1(4) 1_545 2_645 ?
Zn1 O2 O7 112.8(7) . 3_665 ?
O3 O2 O7 94.7(7) 2_645 3_665 ?
O3 O2 O7 149.3(7) 3_666 3_665 ?
As2 O2 O7 73.3(9) 1_545 3_665 ?
O4 O2 O7 91.6(7) 1_545 3_665 ?
O1 O2 O7 123.6(7) 2_645 3_665 ?
Zn1 O2 O6 41.5(3) . 3_655 ?
O3 O2 O6 95.4(5) 2_645 3_655 ?
O3 O2 O6 134.8(5) 3_666 3_655 ?
As2 O2 O6 71.8(7) 1_545 3_655 ?
O4 O2 O6 52.0(4) 1_545 3_655 ?
O1 O2 O6 65.9(4) 2_645 3_655 ?
O7 O2 O6 71.5(6) 3_665 3_655 ?
Zn1 O2 As 70.5(3) . 2_645 ?
O3 O2 As 27.7(3) 2_645 2_645 ?
O3 O2 As 88.7(4) 3_666 2_645 ?
As2 O2 As 150.2(8) 1_545 2_645 ?
O4 O2 As 118.3(4) 1_545 2_645 ?
O1 O2 As 28.6(2) 2_645 2_645 ?
O7 O2 As 113.6(7) 3_665 2_645 ?
O6 O2 As 82.9(3) 3_655 2_645 ?
Zn1 O2 As 67.3(3) . 3_666 ?
O3 O2 As 99.3(5) 2_645 3_666 ?
O3 O2 As 26.7(3) 3_666 3_666 ?
As2 O2 As 93.1(6) 1_545 3_666 ?
O4 O2 As 78.2(3) 1_545 3_666 ?
O1 O2 As 66.8(3) 2_645 3_666 ?
O7 O2 As 165.9(7) 3_665 3_666 ?
O6 O2 As 108.4(4) 3_655 3_666 ?
As O2 As 80.1(3) 2_645 3_666 ?
Zn1 O2 As3 74.8(9) . 1_545 ?
O3 O2 As3 164.0(9) 2_645 1_545 ?
O3 O2 As3 96.7(7) 3_666 1_545 ?
As2 O2 As3 5.6(10) 1_545 1_545 ?
O4 O2 As3 27.0(8) 1_545 1_545 ?
O1 O2 As3 117.1(9) 2_645 1_545 ?
O7 O2 As3 77.3(10) 3_665 1_545 ?
O6 O2 As3 69.0(8) 3_655 1_545 ?
As O2 As3 145.1(8) 2_645 1_545 ?
As O2 As3 89.4(7) 3_666 1_545 ?
As O3 O2 101.3(5) . 2_655 ?
As O3 O2 103.2(6) . 3_666 ?
O2 O3 O2 106.5(5) 2_655 3_666 ?
As2 O4 As3 30.9(18) . . ?
As2 O4 Zn2 106.0(10) . 4_576 ?
As3 O4 Zn2 90.8(15) . 4_576 ?
As2 O4 Zn2 109.1(10) . . ?
As3 O4 Zn2 97.2(15) . . ?
Zn2 O4 Zn2 123.1(6) 4_576 . ?
As2 O4 Zn1 117.8(11) . 1_565 ?
As3 O4 Zn1 148.7(18) . 1_565 ?
Zn2 O4 Zn1 104.4(5) 4_576 1_565 ?
Zn2 O4 Zn1 97.0(4) . 1_565 ?

As2 O4 O6 108.4(10) . 3_665 ?
As3 O4 O6 124.2(15) . 3_665 ?
Zn2 O4 O6 144.2(7) 4_576 3_665 ?
Zn2 O4 O6 52.2(3) . 3_665 ?
Zn1 O4 O6 50.0(3) 1_565 3_665 ?
As2 O4 O5 119.0(11) . 3_666 ?
As3 O4 O5 130.5(15) . 3_666 ?
Zn2 O4 O5 54.8(3) 4_576 3_666 ?
Zn2 O4 O5 130.4(6) . 3_666 ?
Zn1 O4 O5 50.6(3) 1_565 3_666 ?
O6 O4 O5 99.0(5) 3_665 3_666 ?
As2 O4 O8 7.2(14) . . ?
As3 O4 O8 35.0(19) . . ?
Zn2 O4 O8 102.0(12) 4_576 . ?
Zn2 O4 O8 116.2(12) . . ?
Zn1 O4 O8 113.9(9) 1_565 . ?
O6 O4 O8 111.1(11) 3_665 . ?
O5 O4 O8 111.8(12) 3_666 . ?
As2 O4 O2 71.8(11) . 1_565 ?
As3 O4 O2 102.6(18) . 1_565 ?
Zn2 O4 O2 115.1(5) 4_576 1_565 ?
Zn2 O4 O2 117.6(5) . 1_565 ?
Zn1 O4 O2 46.2(3) 1_565 1_565 ?
O6 O4 O2 68.1(4) 3_665 1_565 ?
O5 O4 O2 69.9(4) 3_666 1_565 ?
O8 O4 O2 67.7(8) . 1_565 ?
As2 O4 O6 87.5(10) . 2_655 ?
As3 O4 O6 59.7(16) . 2_655 ?
Zn2 O4 O6 42.6(3) 4_576 2_655 ?
Zn2 O4 O6 96.2(4) . 2_655 ?
Zn1 O4 O6 145.4(5) 1_565 2_655 ?
O6 O4 O6 147.4(6) 3_665 2_655 ?
O5 O4 O6 97.4(4) 3_666 2_655 ?
O8 O4 O6 88.3(9) . 2_655 ?
O2 O4 O6 144.4(5) 1_565 2_655 ?
As2 O4 As3 71.3(12) . 4_575 ?
As3 O4 As3 77.0(17) . 4_575 ?
Zn2 O4 As3 159.9(9) 4_576 4_575 ?
Zn2 O4 As3 44.9(8) . 4_575 ?
Zn1 O4 As3 93.9(9) 1_565 4_575 ?
O6 O4 As3 47.8(8) 3_665 4_575 ?
O5 O4 As3 144.4(9) 3_666 4_575 ?
O8 O4 As3 77.1(14) . 4_575 ?
O2 O4 As3 83.4(9) 1_565 4_575 ?
O6 O4 As3 117.6(9) 2_655 4_575 ?
As2 O4 O4 87.3(9) . 4_575 ?
As3 O4 O4 79.1(15) . 4_575 ?
Zn2 O4 O4 135.0(6) 4_576 4_575 ?
Zn2 O4 O4 21.9(4) . 4_575 ?
Zn1 O4 O4 106.5(4) 1_565 4_575 ?
O6 O4 O4 56.7(3) 3_665 4_575 ?
O5 O4 O4 150.3(4) 3_666 4_575 ?
O8 O4 O4 94.3(11) . 4_575 ?
O2 O4 O4 109.8(4) 1_565 4_575 ?
O6 O4 O4 97.4(5) 2_655 4_575 ?
As3 O4 O4 27.5(8) 4_575 4_575 ?
As O5 Zn1 120.0(6) 1_545 3_656 ?

As O5 Zn1 121.8(6) 1_545 . ?
Zn1 O5 Zn1 102.7(4) 3_656 . ?
As O5 Zn2 122.2(6) 1_545 2_645 ?
Zn1 O5 Zn2 91.3(4) 3_656 2_645 ?
Zn1 O5 Zn2 91.8(4) . 2_645 ?
As O5 O4 130.8(7) 1_545 3_666 ?
Zn1 O5 O4 49.1(3) 3_656 3_666 ?
Zn1 O5 O4 106.7(5) . 3_666 ?
Zn2 O5 O4 42.9(3) 2_645 3_666 ?
As O6 Zn1 135.1(6) 1_545 3_655 ?
As O6 Zn2 130.3(6) 1_545 3_665 ?
Zn1 O6 Zn2 94.5(4) 3_655 3_665 ?
As O6 O4 163.9(7) 1_545 3_665 ?
Zn1 O6 O4 52.7(3) 3_655 3_665 ?
Zn2 O6 O4 46.7(3) 3_665 3_665 ?
As O6 O4 94.3(5) 1_545 2_645 ?
Zn1 O6 O4 129.9(5) 3_655 2_645 ?
Zn2 O6 O4 38.2(3) 3_665 2_645 ?
O4 O6 O4 77.4(3) 3_665 2_645 ?
As O6 O2 114.6(6) 1_545 3_655 ?
Zn1 O6 O2 42.1(3) 3_655 3_655 ?
Zn2 O6 O2 104.6(4) 3_665 3_655 ?
O4 O6 O2 59.9(4) 3_665 3_655 ?
O4 O6 O2 118.9(5) 2_645 3_655 ?
As3 As2 O8 107(4) . . ?
As3 As2 O4 81(4) . . ?
O8 As2 O4 164(3) . . ?
As3 As2 Zn2 66(3) . 4_576 ?
O8 As2 Zn2 129(3) . 4_576 ?
O4 As2 Zn2 41.0(7) . 4_576 ?
As3 As2 O2 156(4) . 1_565 ?
O8 As2 O2 94(2) . 1_565 ?
O4 As2 O2 75.8(10) . 1_565 ?
Zn2 As2 O2 92.9(8) 4_576 1_565 ?
As3 As2 Zn2 71(3) . . ?
O8 As2 Zn2 156(3) . . ?
O4 As2 Zn2 39.4(7) . . ?
Zn2 As2 Zn2 73.1(7) 4_576 . ?
O2 As2 Zn2 93.4(8) 1_565 . ?
As2 As3 O4 68(4) . . ?
As2 As3 O8 44(3) . . ?
O4 As3 O8 111(3) . . ?
As2 As3 Zn2 96(4) . 4_576 ?
O4 As3 Zn2 48.1(12) . 4_576 ?
O8 As3 Zn2 118(3) . 4_576 ?
As2 As3 Zn2 91(4) . . ?
O4 As3 Zn2 44.8(11) . . ?
O8 As3 Zn2 130(3) . . ?
Zn2 As3 Zn2 79.4(13) 4_576 . ?
As2 As3 As 167(4) . 2_645 ?
O4 As3 As 100(2) . 2_645 ?
O8 As3 As 149(3) . 2_645 ?
Zn2 As3 As 77.3(13) 4_576 2_645 ?
Zn2 As3 As 77.3(12) . 2_645 ?
As2 As3 O4 98(3) . 4_576 ?
O4 As3 O4 76.8(15) . 4_576 ?
O8 As3 O4 98(2) . 4_576 ?

Zn2 As3 O4 32.0(5) 4_576 4_576 ?
Zn2 As3 O4 111.2(15) . 4_576 ?
As As3 O4 81.9(11) 2_645 4_576 ?
As2 As3 O2 18(3) . 1_565 ?
O4 As3 O2 50.5(14) . 1_565 ?
O8 As3 O2 61(2) . 1_565 ?
Zn2 As3 O2 80.0(12) 4_576 1_565 ?
Zn2 As3 O2 79.8(11) . 1_565 ?
As As3 O2 150.3(17) 2_645 1_565 ?
O4 As3 O2 89.0(10) 4_576 1_565 ?
As2 As3 O4 96(3) . 4_575 ?
O4 As3 O4 73.8(15) . 4_575 ?
O8 As3 O4 118(3) . 4_575 ?
Zn2 As3 O4 109.1(15) 4_576 4_575 ?
Zn2 As3 O4 30.9(5) . 4_575 ?
As As3 O4 76.7(10) 2_645 4_575 ?
O4 As3 O4 139.8(15) 4_576 4_575 ?
O2 As3 O4 93.1(11) 1_565 4_575 ?
As2 O8 As3 29(2) . . ?
As2 O8 O4 9.2(18) . . ?
As3 O8 O4 34.1(18) . . ?
_diffrn_measured_fraction_theta_max_diffrn_reflns_theta_full_diffrn_measured_fraction_theta_full_refine_diff_density_max
4.008_refine_diff_density_min-1.706_refine_diff_density_rms
0.491

0.916
26.46
0.916