721
The CanaclianMineralogist Vol. 37, pp. 72r-729 (1999)
THECRYSTAL STRUCTURE OF CHOLOALITE
ANITA E. LAM AND LEE A. GROAT1
Department of Earth and Ocean Sciences,University of British Columbia, Vancouver, British Columbia V6T IZ4, Canad.a
JOEL D. GRICE AND T. SCOTT ERCIT
Research Division, Canadian Museum of Nature, P.O. Box 3443, Station D, Ottawa, Ontario KIP 6P4, Canada
ABSTRACT
The crystal structure of choloalile, (Cu27eSb6 21)13 eo(Pbz roCao:o)>: 66Te6 6sO1s s6Cl6 gz, a 12.520(4) A, V SAy4 43, space grotp P4fi2, Z = 4, has been solved by Patterson and direct methods, and refined to an R index of 5.3Vobased on 956 unique reflections measuredusing MoKct radiation on an automatedfour-circle diffractometer. The structure consists of distorled TeO6 octahedra, Cu$5 squarepyramids (where $ = O and CD, Pb(l)Oe triaugmented trigonal prisms, and Pb(2)Orz icosahedra.The Pb(l)Oe polyhedra polymerize to form a three-dimensional network, as do the CuOs squarepyramids and Pb(2)Orz polyhedra The two networks fit together in three-dimensional space,leaving voids that are filled by the TeO6 octahedra.It is likely that the ideal formula of choloalite is CuPbTea+2O6.with CuOa squareplanes as opposed to Cu05 squarepyramids.
Keywords'.choloalite, crystal sfucture, tellurite, lead, copper.
Souuans
La structue cristallinede la choloalite,(Cu27eSb621);366(PbzzoCao:o)>:o6Te66601366Clsez, a 12.520(4) L,V geXD 43, groupe spatial P432, Z = 4, a 6t6 r6solue par m6thodesde Patte$on et m6thodes directes,et affin6e jusqu'd un r6sidu R de 5.37o d la lumibre de 956 rdflexions uniques mesur6esau moyen de rayonnement MoKo avec un diffractombtre automatis6 d quatre cercles. La sffucture contient des octabdresdifformes TeO6, des pyramides carr6esCuS5 (d = O and Cl), des prismes trigonaux triaugmentdsPb(1)Oe, et des icosabdresPb(2)O12. Les polydfues Pb(1)Oe sont polym6risds pour donner une trame tri- dimensionnelle, tout comme les pyramides carrdesCu$5 et les polyddres Pb(2)O12.Les deux trames sont agenc6esensemble dans les trois dimensions, et les espacesvides qui en r6sultent sont remplis par les octaddresTeO6 Il semble probable que la formule id6ale de la choloalite est CuPbTea+2O6.et que la structure contient des plans carr6sCuOa plutdt que despyramides carr6esCuS5.
(Traduit par la R6daction)
Mots-c16s:choloalite, structrrrecristalline, tellurite, plomb, curvre
INrnooucrroN The structure of choloalite was solved as part of a long-term project on the crystal chemistry of the Te- The type specimen of choloalite was described by oxysalt minerals. Williams (1981) from waste rock in the tunnel at the Mina La Oriental, Moctezuma, Mexico. The type mate- PnBvrous Wom rial consists of a matrix of intensely altered rhyolite vitrophyre crossed by veins of crystalline crusts and Using powder X-ray-diffraction data,Williams (1981) choloalite crystals. Soon after the discovery of the type showed that choloalite is isometric. The refined unit-cell material, sampleswith tiny crystals of choloalite were dimensions were reported to be a 12.519 A for the type found between the dumps of the Joe and Grand Central specimen and 12.576 A for the Tombstone sample. The shafts at Tombstone, Arizona. Choloalite also was de- larger cell edge of the Tombstone specimen was attrib- scribed by Roberts et aI. (1994) from the McAlpine uted to the presenceof minor amounts of antimony. Wet- mine, Tuolumne County, California. chemical analysis of the type material (Table l) gave the empirical formula CuPb(Tea* 03 )2.H2O.
I E-mail address'.lgroat@eosubc ca 722
TABLE 1 CHEMICAL COMPOSITION OF CHOLOALITE (program XMAQNT by C. Davidson, CSIRO). The re- sults ofthe analysis are given in Table 1, together with Oxides Williams Thisstudy Elements Williams Thisstudy (1981). (wt %) (1981f (apfu) (1981f the data of Williams An attempt was made to obtain an infrared spectrum CaO trae 050 o17 of choloalite, using a Fourier-transform infrared spec- Pbo 330 31 22 Pbt* 294 trometer equipped with a diamond-anvil microsample CUO 110 It 81 Cu'. 241 cell. The results show considerably more H2O than ZnO 037 zn2' 009 could possibly be accommodated in the structure of SbzOs (ace 110 sbu* ua@ 013 choloalite. Since this is undoubtedly evidence of TeO2 507 5181 le 631 615 adsorbed H2O, the results of the infrared experiment cl 119 0,64 were consideredto be inconclusive. La H,O 34 H- 750 The crystal used in this study is from the Mina Oriental locality (Canadian Museum of Nature sample -o27 cf' 2206 1803 MI58777). The crystal is optically isotropic and shows roTAL 98 1 97 73 no evidence of twinning. It was mounted on a Siemens Note: Analyses are normalized on 12 cations perfomula unit *AveEge offour wet chemi€l analyses for CuO, and three for PbO and TeO2 Water by the P3 automated four-circle diffractometer, and cell dimen- Penfield method sions (Table 2) and intensity data were collected accord- ing to the procedureof Lam et aI. (1998). One octant of reflections (3 I 86 measurements,exclusive of standards) The formula of choloalite was revised to CuPb(TeO3)2 was collected from 3 to 60" 20',64 reflections were re- by Powell et al. (1994), who synthesizedcrystals with jected becauseof asymmetrical backgrounds, and one this formula by fusion of stoichiometric amounts of becauseof peak asymmetry. Fifteen strong reflections CuO, TeOz, and PbO. No weight loss was detectedwith uniformly distributed with regard to 20 were measured heating to 400oC, and infrared spectroscopywas used at 5" intervals of V (the azimuthal angle corresponding to confirm the absenceof H2O. Powder X-ray-diffrac- to rotation of the crystal about its diffraction vector) tion spectra of the synthetic material were found to be from 0 to 355o, after the method of North et al. (1968). similar to those obtained from type choloalite, with These data (920 measurements)were used to calculate some additional weak reflections. Powell et al. (1994) an absorption correction. The merging R index for the concluded that choloalite is anhydrous, and that the H2O V-scan data set decreasedfrom 5.17obefore the absorp- determined by Williams (1981), using only 156 pg of tion correction to 2.lVo after the absorption correction. material, was adsorbed on the surface of the mineral This correction was then applied to the entire dataset; particles. The cell dimen-sion4 obtained from the syn- minimum and maximum transmissions were 0.88 and thetic phasewas 12.514A, and indexed reflections sug- 0.68, respectively. The data were also corrected for gestedpossible space groups P23, Pm3, P432, P43m, Lorentz, polarization and background effects, averaged or Pm3m (none of which would result in systematic and reduced to structure factors. Of the 956 unique re- absences). flections, 455 were classed as observed [I > 3o(I)]. Powell et al. (1994) also suggested an additional occurrenceof choloalite. This was basedon the original Srnuctuns Sor-urroN A\D REFINEMENT description of balyakinite (Spiridonov 1980), which occurs with teinite and two unnamed Cu, Pb tellurites The SiemensSHELXTL PC systemof programswas with formulae CuPb(TeO3)O and CuPb(TeO3)2(as de- used throughout this study. Scattering curyes for neu- rived from electron-microprobe analyses). The latter tral atoms together with anomalous dispersion coeffi- formula is the same as that obtained by Powell et al. cients were taken from Cromer & Mann (1968) and (1994) for their synthetic material. Cromer & Liberman (1970). Miscellaneous data on the collection and refinement are siven in Table 2. Exlenluetrar-
An electron-microprobe analysis was obtained using a JEOL 733 electron microprobe with Tracor Northern TABLE2 CHOLOALITE 5500 and 5600 automation. The wavelength-dispersion a (A) 12520(4) Rad/mono MoKoy'gEphite mode was used. The operating conditions were as fol- v(Al 1e63(2) rotal 3186 lows: voltage 15 kV, beam current 20 nA, and beam lF.l P41s2 r" (,)] 455 diameter 5 pm. Data for Ca, Cu, Sb, and Te were col- spae sroup [,- Rer6) 53 lected for 25 s; data for Cl, Zn and Pb were collected for z 4 50 s. The following standardswere used: scapolite crystalsize (mm) 0 04 x 0 04 x 0 05 wR (Vo\ 5 9 (ClKct), CaTaaOll (CaKct), cuprite (CuKct), ZnWO+ p (MoKo; mm-I1 35 6 (ZnKa), stibiotantalite (Sbzct), and Pb2Te3Os(TeZct R - - F.'t = - F,,l'I r.'f"', * =t >tn rF.,.n [I (' lF" Zw and PbMa). Data were reduced using a PAP routine THE CRYSTAL STRUCTURE OF CHOLOALITE I Z-)
TABLE3 ATOMICPARAMETERS FOR CHOLOALITE
-5(9) Te ooa12(2) 04406(2) o 3401(2) 204(11) 265(11) 201(10) 34(9) 47(8) 22416) Cu ra 023213) -o 5179(3) 1e3(33) 199(27) 199(27) -11(15) 11(15) 91(22) 197(17\ '73(7) Pb(l) O 1e27(1) O 1s27(11 O 1s27(1) 378(7) 378(7) 378(7) '73(7) -73(7) 378(4) -76(9) Pb(2\ 3/8 38 3/8 265(17) 265(17) 265(17) -76(s) -76(s) 265(10) o(1) 0 0261(23) O 1205(23) 026A2\24) 413(65) q2\ o 1759(18) 03274(A) O 3738(17) 232(481 o(3) o 1857(19) O5200(18) O2613(18) 248(50) ct 7t8 7t8 7tA s4A|J28) s481J2A]| 548(128) 24(92) 24lg2l 24(92) u8\74) *U, and U val6 are listed x loa ff
TABLE 4 SELECTED INTERATOMIC DISTANCES (A) ANO ANGLES f) FOR CHOLOALITE The mean value of le - \ was found to be 0.85, indicative of a non-centrosymmetric space-group.Sys- Te-O('l)a 1 e7(3) o(2)e-Cu-O(3X x2 % 0(10) tematic absencesin the original dataset suggestedthe -o(1)b 2 9s(3) o(2)e-Cu o(3)h x2 857(1 0) spacegroups P4332 andP4fi2. The structurewas solved o(2) 1 e0(2) O(2)e cu-cl x 2 93 4(7) by Pattersonand direct methods and refined in P\32to -o(3) 1 e2(2) O(3)f-Cu-Cl x2 923(7) -o(3)c
TABLE5 BOND-VALENCE-ARMNGEMENT IN CHOLOALITE structure of Bi2TeaO11can be described as distorted octahedra. In the crystal structure of choloalite, two Pb(1) Total additional O atoms, at distancesof 2.95 and 3.05 A, can o(1) 12'l 036x31 142 be considered to form bonds with the atom at the Te 016 009x3U position (contributing0.16 and 0.13 valenceunits, vz, o(2) 113 055x2J 0 17x3J 026x6J 211 respectively). The resulting polyhedron is a distorted o(3) 107 o66x2J 007x61 216 octahedron,with three weak bonds occurring opposite three strong bonds. As suggestedby Brown (1974), the bond-valence sum of each tans pair is approximately equal. The environment corresponds to type "C" of 078 Brown (1974), although the valence ratio suggestscon- 393 268 186 198 figuration "A" (with two strong, two intermediate, and *Calalated from the curuesof Brown(1981), as modifiedby Back (1990)for weak bonds). The mean Te-O distance is 2.40 A, Te, and thoseof Brese& O'Keeffe(1991) for bondsto Cl two and the O-Te-O anglesrange from 65.1 to 127.6', with a mean value of 89". The variance of the octahedron angle is 354.14, the mean quadratic elongation of the dipyramid, with a lone pair of electrons occupying one octahedron (Robinson et al. L97l) is 1.2296, and the corner of the equatorial triangle. Brown (1974), how- polyhedron volume is 14.47 A3. The lone pair of elec- ever, assumedthat the coordination environment of Tea* trons is most likely located on the side of the Te atom (and Sn2+,Sb3*, I5*, and Xe6+)is an octahedrondistorted opposite the three closest O atoms, and within the vol- by a lengthening of some of the bonds on one side. Back ume defined by the Te atom and the three O atoms with (1990) showed that Te4+ can be coordinated by up to the largest Te-O distances and O-Te-O angles. It is eight anions,and Rossell e/ al. (1992) demonstratedthat unlikely that the atom at the Ze position forms a bond the coordination polyhedra ofthe four Tea* atoms in the with the atom at the nearest Cl site, given the distance
T^ Cu
Pb(1) Pb(2)
FIc. 1. Coordination polyhedra ofcations in the structureofcholoalite. O atoms are shown as shadowed spheres,the Cl atom as an open, larger sphere. THE CRYSTAL STRUCTURE OF CHOLOAIITE 725
(3.701A), the possiblebond-valence contribution (0.03 and3.14A latt x:; mean 2.81 A), a"a the O-Pb(1)-O r;a), and the presenceof Cu atoms at a distanceof 3.206 anglesrange from 55.1 to 122.3" (mean 87.4'). The and 3.330A. lengths of the polyhedron-edges are 2.78,3.07, 3.17, The atom at the Cu site, special position l2d (1/8,x, 3.18,3.46,3;14,and 3.92 A i .ll x3). The polyhedron ll4+x), is bonded to four oxygen atoms in approximate volume is 40.6 43. The coordination polyhedron is square-planarcoordination (the-oxygen atoms deviate somewhat distorted, suggestingthe presenceof a lone from a common plane by +Q.Q2A). The Cu-O distances pair of electrons.The results of the crystal-structurere- are 1.86 andl.92 A (both X2. mean 1.89Al and the O- finement show that the Pb(l) site is completely occu- Cu-O anglesare 86 and 94" (both X2, mean 90o). If the pied by Pb2+. Cu site is assumedto be fully occupied by Cu2*, the The atom at the Pb(2) site, special position 4a (318, resulting bond-valence sum is 2.26 vz. However, the 318,3/8),is coordinated by twelve O atoms, forming a electron-microprobe data suggest 92.'l%oCtt,4.3Vo Sb, distorted icosahedron.The Pb(2)-O distances are 2.56 and 3.0VoZn at the Cz site (resulting in bond-valence and 3.31A (bottrX6; mean2.94 b,and the O-Pb12;O sums of 2.33 and 2.34 vu for Sb3* and Sbs*. resDec- angles range from 53.0 to 142.5" (mean 90.7"). The tively). The structurerefinement shows 93(4Va Cu and lengths of the polyhedron edges are 2.95 and 4.77 A 7(4)VoSb atthe Cu position (resulting in bond-valence (both x3), and2.76, 2.80, 3.17. and 3.37 A (all x6). sums of 2.40 for both Sb3+and Sb5*).Assuming no va- The polyhedron volume is 57.9 A3. The structure re- cancies,the results show that the atom at the Cz site rs finement shows 7O(2)VoPb and 30(2)VaCa at the Pb(2) overbonded by a minimum 0.26 vu. However, there rs position, which is in good agreementwith the electron- an additional site (labeled CI) at a distance of 2.531 A microprobe resdts (79qo Pb and 2lvo Ca). Other miner- from the Ca position. The structure refinement shows als with twelve-coordinated Pb2+include osarizawaite that the C/ site is predominately occupied by Cl ; re- (Giuseppetti & Tadini 1980), plumbojarosite finement of the site occupancy shows92(12)7oCl at the (Szyma.iski 1985) and senaite(Grey & Lloyd 1976).All Cl position, although the electron-microprobedata sug- show six equal short and six equal longer Pb-O dis- gest only 0.64 Cl atoms per formula unit. There is no tances, with mean values of 2.82 to 2.92 A. Although evidence for any other atom or molecule at the C/ posi- the Pb(2)-O distancesin choloalite show a larger range, tion; asnoted previously, the resultsof the infrared spec- the mean value is close to those for the other minerals. troscopy experiment were inconclusive as to the It is difficult to describe a crystal structure as com- presenceof OH or H2O. If the atom at the Ca position is plicated as that of choloalite. We begin by assumingfull consideredto be bonded to one Cl atom in addition to occupancy of the Cl position and a square-pyramidal four oxygen atoms,the resulting sphereof coordination coordination sphere around the atom at the Cu site (the is almost a square pyramid (actually a very distorted alternatedescription, of a structurewith a vacant C/ site trigonal dipyramid), with a mean Cu-d (d: unspecified and Cu with square-planarcoordination, is only slightly anion) distance of 2.02 A. a mean O-9r-0 angle of different). We may consider the polymerization of co- 91.4o, and,a polyhedron volume of 6.3 A3. ordination polyhedra by simple rotation around an atom It is likely that the Cl in choloalite servesto balance (generally a central cation) at a special position. The C/ the excesspositive chargeintroduced by Sb. Is the Sb at site,at specialposition 4D (718,718,7/8),lies at theinter- the Cu position trivalent or pentavalent?According to section of one axis of twofold and one axis of threefold Shannon(1976), the ionic radii of Cuz+and Sb3*in five- rotation. The atom at this site forms bonds with atoms fold coordination, and of-Sb5* in sixfold coordination, at th-reeCa positions (each of which is on an axis of are 0.65, 0.80, and 0.60 A, respectively.This suggests twofold rotation). Because of this, each Cu$s square that the Sb at the Ca position is pentavalent.In addition, pyramid is attachedto two others by comer-sharing of the chemical formulae obtained from both the electron- the atom or molecule at the Cl site, forming a "pin- microprobe and crystal-structure analyses (see below) wheel" (Fig. 2a). In addition, each CuS5 polyhedron are only (approximately) charge-balancedwith pentava- sharestwo trans O(2)-O(3.) edges llength 2.57 A) with lent Sb. two TeO6 octahedra, and the other trans O(2)-O(3) It is entirely possible that if the Cu site was only edges(length 2.76 A) with two Pb(2)Orzpolyhedra. The occupied by Cu, the bond distances would be slightly lengths of the unsharedO(2)-Cl and O(3)-Cl edgesare longer,resulting in lower bond-valencesums. In this case, 3.26 and3.20 A, respectively. In addition, each Cu$5 there would be no need for additional negative charge polyhedron is linked by corner-sharing to additional at the Cl position, and the true coordination would be TeO6 octahedra(x4) and Pb(l)Oe polyhedra (x2). square-planar.However, it is interesting to note that of The Pb(l\ siteslie on axesofthreefold rotation. Each the 94 Cu-oxysalt minerals listed in the compendium Pb(l)Oe polyhedron shares edges with three others, by Eby & Hawthome (1993), only three show Cu in forming an additional "pinwheel" (Fig. 2b). The "pin- fourfold coordination, and ll in fivefold coordination. wheels" polymerize to form a three-dimensional net- The atom at the Pb(l) site, specialposition 8c (x,x,x), work (Fig. 3). is coordinatedby nine O atoms,forming a triaugmented Like the Cl sites, the Pb(2) positions lie at intersec- trigonal prism. The Pb(l)-O distancesare 2.46,2.83, tions of one axis of twofold and one axis of threefold 726 THE CANADIAN MINERALOGIST
FIc 2. "Pinwheels" in the crystal structure of choloalite: (a) three CuS5 polyhedra; (b) four Pb(1)Oe polyhedra; (c) seven Pb(2)O12polyhedra linked by six CuS5 polyhe&a.
ar--
Ia1 I
FIc 3. Three-dimensional network of Pb(l)Oq polyhedra. The Te atoms are shown as spheres.The positions ofthe 41 axes are evident. '727 THE CRYSTAL STRUCTUREOF CHOLOALITE
Ta1 I
Frc. 4. Three-dimensional network of CuQ5 and Pb(2)O12polyhedra The Te atoms are shown as spheres.
rotation. Individual Pb(2)Ot2 polyhedra are notjoined; however, each is linked by the sharedO(2)-O(3) edges to six Cu$5 polyhedra. Each Cu$5 polyhedron is then joined through the trans 0(2)4(3) edgeto an additional Pb(2)Ol2 polyhedron. The result is yet another "pin- wheel" (Fig. 2c). These polymerize to form an addi- tional three-dimensionalnetwork (Fig. a). The two tlree-dimensional networks are linked by the two trans O(2)-O(2)-O(2) faces (edge length 3.17 A, X3) of eachPb(2)O12 icosahedron, which are shared with adjacent Pb(l)Oe polyhedra. The spacesare filled with TeO6 octahedra (note that the Te atom, alone among the cations in the choloalite structure,does not lie on an axis of rotation) . The linkage of the TeO6 polyhedra with neighboring polyhedra is shown in Figure 5. Each TeO6 octahedron sharesone triangular O(2)-O(3)-O(3) face with a Pb(2)O12polyhedron; the lengths of the shared edgesare 2.80,2.95,and3.3'7 A. In addition,each TeO6 polyhedron sharesone O(2)-O(3) edge Q.57 A) *ittt an adjacent Cu05 square pyramid, and one O(3)-O(3) (2.95 A) and two O(l)-O(3) edges(2.96 x 2 A) wirh Frc. 5. Linkage of adjacent polyhedra to the TeO6 octahe- three different TeO6 octahedra.Furthermore, one O(1)- dron. Bonds are shown for the central TeO6 octahedronand (3.18 O(1) edge A) and one O(l)-O(2) edge (2.78 A) those adjacentpolyhedra linked to it by sharededges. Only are shared with adjacent Pb(l)Oe polyhedra. The three the cenffal cation is shown for those polyhedra that link by unsharededges have lengthsof 4.60,4.81, and 5.08 A. shared corners. The O atoms are shown as shadowed Finally, each TeO6 polyhedron is linked by corner- sphereswith no labels. 728 THE CANADIAN MINERALOGIST sharingto additionalCu$s (x2), TeO6(X2), Pb(l)Oe, AcruowLsocel,mNts and Pb(2)Orz polyhedra. The authors thank J.M. Mclntosh for her help with DrscussroN sample preparation for the electron microprobe, and M.E. Back for the loan of a copy of his M.Sc. thesis. The empirical formula of choloalite, based on the We also thank G. Giester and A. Pring for their con- electron-microproberesults, and calculatedon the basis structive reviews of the original manuscript. Financial of 12 cationsperformulaunit, is (Cuz arSborzZno.o)x03 support was provided by the Natural Sciences and En- (PbzosCao n)>za2Te615O1s s3Cl6 6a. This is similar to the gineering Research Council of Canada in the form of a formula based on the structure analysis, which is Research Grant to LAG, and by equipment grants from (CuzrqSbo zr):3 66(Pb2TsCas 36)13 66Te6 ssOls ooClo sz. the British Columbia Science and Technology Devel- The empirical formula calculated from the chemical data opment Fund and the University of British Columbia. in Williams (1981) (on the basis of 12 cations per for- mula unit) is CuzzsPbz.qTe631O1s31.(H2O)375.Our re- RBrsRENcrs sults show a C/ position that is approximately 64to92qo occupied by Cl, which presumably is there to balance B.c.cr, M.E. (1990): A Study of Tellurite Minerals: their Physi- the excesspositive charge introducedby Sb5* inthe Cu cal and Chemical Data Compatibility, and Structural Crystallography. M.Sc. thesis, Univ. Toronto, Toronto, site, and would not be presentbut for the Sb. Since there Ontario. is no evidence to suggestthat choloalite is normally a hydrous mineral, the ideal formula is likely CuPb BRAr\DSTATTER,F. (198 1): Non-stoichiometric, hydrothermally Tea*2O6,as suggestedby Powell et al. (1994). synthesizedcliffordite. TschermaksMine ral. P etrogr. Mitt. Choloalite is one of five cubic Te-oxysalt minerals; 29, t-8. the others are cliffordite, mcalpineite, winstanleyite, and yafsoanite. Only the structures of cliffordite and Bnesn, N E. & O'Klprrr, M. (1991): Bond-valenceparameters yafsoanite are known. Brandstdtter (1981) showed that for solids. Acta Crystdllogr.847, 192-197. there are three distinct cation sites in the structure of Bnowx, I D. (1974): Bond valence as an aid to understanding cliffordite. The atom at the Te position, which is com- the stereochemistry of O and F complexes of Sn(II), Sb([), pletely occupied by Tea*, is coordinated by five Te(IV), I(V) and Xe(VI) J. Solid State Chem.ll,2I4-233- (Brandstiitter 1981) or more (Back 1990) O atoms. There are also two Upositions in the crystal structureof - (1981): The bond-valencemethod: an empirical ap- cliffordite; each is coordinated by eight O atoms form- proach to chemical structure and bonding. In Structure and ing hexagonal bipyramids. The crystal structure of Bonding in Crystals II (M. O'Keeffe & A. Nawotsky, eds.). (1-30). yafsoanite was most recently studied by Jarosch & Academic Press,New York, N Y. Zemann (1989), who showed that it is a garnet-type Cnorr,ren,D.T. & LIeeRMeN,D. (1970): Relativistic calculation oxide with Ca, Teb+,andZn atomscoordinated by eight, of anomalous scattering factors for X rays. J. Chem. Phys six and four O atoms, respectively. s3,r891-1898. As noted previously, Williams (1981) derived the following parageneticsequence from textural evidence: & MINN, B.J. (1968): X-ray scatteringfactors com- rodalquilarite * choloalite - emmonsite * cerussite. puted from numerical Hartree-Fock wave functions. Acla The first three are all tellurites, suggestingthat the oxi- Crystallogr. A24, 321-324. dation potentials at the type locality were not high Esv, R.K. & HlwrnonNn, F.C. (1993): Structural relations in enough to produce Teo'. The formula and crystal struc- copper oxysalt minerals. I. Structural hierarchy. Acta ture of choloalite are very different from those of the Crystallogr. B,49,28-56 other tellurites. However, the crystal structures of rodalquilarite and emmonsite are similar; both contarn EFFENBERGER,H., ZEMANN,J. & MevBn, H. (1978): Carl- Fe3* (suggesting some degree of oxidation) in octahe- friesite: crystal structure,revision ofchemical formula, and dral coordination. In rodalquilarite, the octahedrashare synthesis Am. Mineral. 63, 847-852. edges to form chains parallel to the b axis. The chains ANDERssoN,S. & Asrndrra,A. (1975): join with Te polyhedra to form planes approximately G.lrv, J., MEUNIER,G., St6r6ochimiedes el6mentscomportant despaires non li6es: parallel to (100), and theseare held together by Te-Cl- Ge (II), As (Iil), Se (IV), Br (V), Sn (II), Sb (III), Te (IV), Te-andhydrogen bonds. In emmonsite,isolated pairs of I (V), Xe (VI), Tl (I), Pb (II), et Bi (III) (oxydes, fluorures Fer+$6octahedra share edges, and are in turn connected et oxyfluorures) J. Solid State Chem.13,142- 159. into a three-dimensionalarray by Te polyhedra. Com- parison of the structureswith the parageneticsequence Gruro, L.M. & PenruE, E. (1987): STRUCTURE TIDY - a of Williams (1981) shows a depolymerization of Fe'*Q6 computer program to standardize crystal sfucture data. "/. octahedrawith progressive crystallization. Appl. Crystallogr. 20, 139-143. THE CRYSTAL STRUCTURE OF CHOLOALITE 729
GrusEpprrrr, G. & Teonvr, C (1980): The crystal structure of Rosselr, H.J., LEBLANC,M., FinBv, G., BBvnN, D.J.M., osarizawaite.N eue s Jah rb. M ineral., M onatsh., 40 | - 407. SrursoN, D.J. & Tlvr-on, M.R. (1992): On the crystal structureof Bi2TeaO11.Aust. J. Chem. 45, 1415-1425. GREv, I.E. & Lrovo, D J. (1976): The crystal structure of senaite.Acta Crystallogr.832, 1509- 1513. SHANNoN,R.D. (1976): Revised effective ionic radii and sys- tematic studies of interatomic distances in halides and Jenoscu, D. & ZEMAI\.N,J. (1989): Yafsoanite: a garnet type chalcogenides.Acta Crystallogr. A32, 7 5l-7 67- calcium - tellurium (VI) - zinc oxide. Mineral. Petrol. 4O, 11 1-1 16. SpRDoNov, E M. (1980): Balyakinite, CuTeO3,anew mineral from the zone ofoxidation. DokI. Acad. Sci. USSR.Earth Lau, A.8., Gnoer, L.A. & Encn, T.S. (1998): The crysral Sci. Sect. 253, 200-202. structure of dugganite, Pb3Zn3Te6+As2Ou,. Can Mineral 36,823-830 SzyMAI(sKI,J.T. (1985): The crystal structureof plumbojarosite PblFeg(SO+)z(OH)612.Can. Mineral. 23, 659-668. Lr P.lce, Y. (1987): Computer derivation of the symmetry elements implied in a structure description. J. Appl Crys- W.qNc, X. & Lms.Au, F. (1996): Influence of lone-pair elec- tallogr. 20,264-269. trons ofcations on bond-valenceparameters Z, Kristallogr. ztt, 437-439 NonrH, A.C.T., Prnr-r-rps,D.C & Merrnws, F.S. (1968): A semi-empirical method of absorption cofiection. Acta WtLlIarras,S.A. (1981): Choloalite, CuPb(TeO3)2.F12O,a new Crystallogr. A24, 351-359. minenl Mineral. Mag. 44, 55-57.
Pownr-1, D W., THoMAs, R.G., Wn-lraus, P.A, Bncn. W D. ZilaeNN, J (1968): The crystal chemistry of the tellurium ox- & Purrasn,I.R. (1994): Choloalite: synthesis and revised ide and tellurium oxosalt minerals. Z. Kristallogr. I27, chemical formula. Mineral. M ag. 58, 505-508. 319-326.
Ronenrs, A.C, ERcrr, T.S., Cnntle, A.J., JoNEs,G.C., (1971): Ztr Stereochemie des Te(IV) gegeniiber Wnnvs, R.S.,CunrroN, F.F.,II & JENSEN,M.C. (1994): Sauerstoff.Monatsh Chem.102, 1209- 1216. Mcalpineite, Cu3TeOu.11r6, a new mineral from the McAlpine mine, Tuolumne County, Califomia, and from the Centennial Eureka mine, Juab Countv. Utah. Mineral. Mag. 58, 417-424.
RouNsoN, K., GrBBs,G.V. & Rrsnl, P H. (1971): Quadratic elongation: a quantitative measureof distortion in coordi- Received July I, 1998, revised manuscript acceptedApril 25, nation polyhedra. Science 172, 567-570. 1999.