The Crystal Structure of Hauyne at 293 and 153 K

Canadian Mineralogist Vol.29, pp. 123-130(1991)

THE CRYSTALSTRUCTURE OF HAUYNEAT 293 AND 153 K

ISHMAEL HASSAN{. ANDH. DOUGLAS GRUNDY Departmentof Geology,McMaster University, Hamilton, Ontario L8S4Ml

ABSTRAcT dre de position dansle casdes atomes d'oxygdne du r6seau, du moins dansnotre echantillon, et nous ne voyons aucune The structure of hauyne, ideally Na6Ca2[Al6Si6O24] r€flexion satellitedans les clich6sde prdcession.Ces r6sul- (SOa)2,has beenrefined using separateintensity data-sets tats diffArent donc du cas de la nosdaneet de la lazurite' collected from the same single crystal at temperatures of danslesquels les atomc d'oxygbnedu r$eau occupentdeux 293 and 153 K, respectively.The refinementswere done ensemblesde positions 24(i), et la pr6sencede r6flexions in spacegroup P43n, and the final R indicesare 0.036and sate[itesd6coule d'une modulation dansla position desato- 0.039 for the 293 and 153 K data sets,respectively. The mes d'oxygbne. Al:Si ratio is l:1; theseatoms are completely ordered. There (Traduit par la R6daction) is positionaldisorder of the interstitialcations (Na, K, and Ca) over three independenr8(e) positions (sitesCl, C2, and Mots-clds:groupe de la sodalite,hauyne, structure cristal- C3) that are closeto eachother on the body diagonalsof line, mise en ordre de groupemants,bordures des domai- the cubic cell. The Cl, A, and C3 sitesare occupiedby nes antiphases. K, Ca, and Na, respectively.The sulfuratom of the SOI- group is displacedoff the 2(a)position to an 8(e)position, but the oxygenatoms have remainedat an 8(e) position, Ixtnooucrrou indicatingthat the SOagroup is in one orientationinstead of two. The presentstudy also suggeststhat OH is a sig- Hauyne, ideally Na5Ca2[Al6Si6O24](SO)2,is a nificant componentof hauyne.There is no positional dis- sodalite-group mineral closely related to the other order of the framework oxygen atoms in this sampleof sulfatic members, nosean and lazurite. These hauyne, and satellite reflections were not observedin X- groups inter- precessionphotographs. minerals contain 56 as the dominant ray Theseresults contrast with generally thosefor noseanand lazurite,wherein the frameworkoxy- stitial anion, and they show complex satel- gen atoms occupy two sets of 24(i) positions and the lite reflections (Saalfeld 1961,Taylor 1967,Schulz observedsatellite reflections arise from the positional modu- 1970,Hassan et al. 1985).The origin of the satellite lation of the framework oxygen atoms. reflectionsis not known in detail, but their presence doesindicate that the structuresof the sulfatic soda- Keywords: sodalitegroup, hauyne, crystal structure, cluster lites are incommensurately modulated; as a conse- ordering, antiphasedomain boundaries. quence, these minerals have been studied by trans- mission electronmicroscopy (lEM; Morimoto 1978, Tsuchiya& Tak6uchi1985, Hassan & Buseck1989a, SoMMAIRE b). The hauyne specimenused in this study doesnot Nous avonsaffin€ la structurecristalline de la hauyne, show satellite reflections on precessionphotographs; de formule id6ale Na6Ca2[Al6Si6O24](SOr2,en utilisant this specimenthus may provide a clue as to the ori- desdonn6es d'intensit€ obtenuespour le m€mecristal d 293 gin of the incommensurate-modulatedstructure of et 153K, respectivement.Les affinements,dans le groupe sulfatic sodalites. spatialP43n, ont donndun indiceR final de 0.036et 0.039, The aluminosilicateframework of the sodalite- respectivement.Le rapport Al:Si est de I i l, et cesato- group mineralshas a l:l Al:Si ratio; theseatoms are messont complbtementordonn6s. Par contre, il y a d6sor- fully ordered.The strusturehas four-memberedrings parmi (Na, dre les cations interstitiels K et Ca) sur les huit of AlOa and SiO4 tetrahedra that are parallel to positions (sites qui 8(e)ind6pendantes CL, C2 et C3), sont form six- rapprochdesI'une de l'autre le long des diagonalesde la {100}. Theserings are further linked to maille cubique.Les sites Cl, A et C3 contiennentK, Ca memberedrings that areparallel to {lll}. The over- et Na, respectivement.Les atomesde soufre du groupe all linkage of theserings givesrise to cubo-octahedral SOi sont ddplacdsde la position 2(a) b,Ia position 8(e), cages(e.9., Fig. I of Hassan& Grundy 1984).The mais lesatomes d'oxyg&ne s'en tiennent i la position 8(e), cages can accornmodate a variety of interstitial indication que le groupe SOapossbde une seuleorientation cations and anions by cooperative rotation of the et non deux. Nos r6sultatsfont penserque le OH seraitun AlOa and SiOo tetrahedra Oy angles dar and ds, composantimportant de la hauyne.Il n'y a aucun d6sor- respectively)from their positions in a fully expanded structure(see Fig. 2 of Hassan& Grundy 1984).The *Presentaddress: Institute for Materials Research,McMas- range of interstitial ions is limited by spatial and ter University, Hamilton, Ontario L8S 4Ml. charge requirements of the framework. t23 124 THE CANADIAN MINERALOGIST

TABLE1. CHEMICALCOMPOSITION OF HAUYNE FROM samesingle crystal was thus collectedat 153K to bet- VAI I E BIACHELLq.SACROFANO. ITALYT ter define the parameters of the interstitial atoms. The cell parameter was determined by the least- Oxlde \fft. o/o Cell contontsl* squaresmethod using monochromatic MoKo radiation and 15 reflections having 10" < U < 35o, Aaoa 27.O AI automatically centeredon a four-circle single-crystal sio2 31.3 SI AG X-ray diffractometer. The cell parameter and other N%o 11.8 Na 4.35 information pertinent to X-ray data collection and K2o K NG refinements are presentedin Table 2. All reflection CaO 11.2 Ca 2.28 intensities were measuredin an octant on a Syntex sog 14.2 s 2.03 P2t diffractometer operating ul^the04 scanmode, 993 with a 20 scan range of (I(oq -0.85') to (Ka2 tMicroprob€ +0.85') and variablescan-rates of 3o to 29.3min-I, Analysisby LlndsayKeller, dependingon the intensity of a preliminary scan. ArizonaState Unlversity The intensitiesofthe two standardreflections,622 r*Basod + = on Al Si 12.0;a=9.120(6) A and 404, monitored after every 50 reflections, did not changeduring the experiment.The data werecor- rected for Lorentz, polarization, background effects, ExpsnrN4sNTnr and sphericalabsorption Qable 2). Equivalent reflections werethen averagedto produceunique data-sets. The hauyne sample used in this study is from All crystallographiccalculations were done using the Sacrafano, Italy (Royal Ontario Museum no. XRAY76 CrystallographicPrograms (Stewart 197O. M35731).A different specimenfrom this locality was chemically analyzed (Table l), and we assumethis composition to be representativeof our material. Srnucruns Rern lgl4er.rr Precession photographs show sharp substructure reflectionsand no satellitereflections. Space group Atomic scattering factors for neutral atoms were P43n was assumed and used in the structure taken from Cromer & Mann (1968).For the frame- refinement. work atoms (Al, Si, and Ol), the initial isotropic An initial refinement with the data set colected temperature-factorsused were those of sodalite, and at 293 K (room temperature) indicates significant initial positional parameters were calculated using positional and substitutional disorder of the inter- the geometricalmodel for sodalite(Hassan & Grundy stitial atoms in hauyne; another data set from the 1984).

TABLE2. CRYSTALDATA* AND INFORMATION ON DATACOI I ECNONFOR HAUYNEAT 293 AND 153 K

Miscellaneous 293 K 153K

a (A) 9.1164(5) 9.1097(8) v tAsl 757.65 755.e8(8) Denslty"4". (S/cm{) 2.41 2.42 Crystalslze (mm) O.23x0.23x0.17 p (cm'1) 13.02 13.06 Maximum20 650 550 0 3cllFl 1il Flnal**R 0.036 0.039 Flnal***Rw 0.03i1 0.me

*Spacegroup P?3n; Z = 1; Radiation/monochromator= Mo/C; MolQ=0.71069A r*R ***R,,"= 211 =X( | FoI - I FcI )lt IFo | ; pw( | Fe| - I FcI )2/tw IFo I /2, * = t. THE CRYSTALSTRUCTURE OF HAUYNE t25

TABLE3. REFINEDAND CALCULATEDOCCUPANCY-FACTORS* AND CHEMICAL FORMULAEFOR HAUYNE

1 2 3 4 c Site Na K Anal. Cation

c1 0.3t 0.19 0.18 0.12K 0.20K c2 0.52 0.30 0.29 0.30Ca 0.30Ca c3 0.54 0.31 0.30 0.54Na 0.54Na

ChemicalFormulae (a)Charge balance model: (Nao.uCar.o\.0)rz.slAosi6o24l(SO4)1.50POH)0.50 (b)Refinemenl: (Na4.3Ca2.4K1.6)26.3[A16S16024l(SOd1.520OH)r.os (SO/2.s3 (c) Chemicalanalysls: (N"c.ssC"z.zsh.sS)t z.salAOSl6O2al

Lijhn& schulz(1968) data: (d)Chemicafanafysis(Naa.s2h2.22j

rcolumn 1: Obtalnedby relinementusing Na scatteringcurve. Column2: Obtainedby convertingcolumn 1 Into K atoms. Column3: Obtainedby convertingcolumn 1 into Ca atoms. Column4: Obtainedby chemicalanalysis. Column5: Obtainedby refinementusing each atom $catteringcurve.

Refinementof the $tructure (Table 3) was done TABLE 4. ATOMIC POSMOML PARAMETEBS,OCCUPANCY FACTORS, AND THERMAL PAFTAMETERS62 x 101 rOn Hetryneerzs alo tsg x on the $etof intensitiesmeasured at room temperature by a full-matrix least-squaresmethod using unit Sh€ O6uparci6 C@dlnat6 MK 153K weightsand a variable overall scale-factor.The posi- 1.0 1/4 1/4 tional coordinates of the framework atoms v 0 0 were refined, as well as their isotropic and subse- 112 112 quently their anisotropic temperature-factors.The u*u"'' I 7 refined temperature-factors(Tables 4, 5) for the 1/4 framework atoms showedno unexpectedvalues, and v 1/2 geometryof the framework (Iable was 0 0 the resulting Q uequtr. I found to be comparable to that sodalite Qlassan & Grundy 1984);this indicatescomplete order among 24(t) 1.0 x 0.1443(5) 0.1443(5) In particular, the temperaturefac- v 0.15n96) 0.1558(6) Al and Si atoms. z 0.,1681(4) 0.4{89(5) tors for Al and Si atoms are of similar magnitude, ueqw. ltm and the framework oxygenatom, 01, occupiesonly (i) positions; theseresults differ from Cl 8(s) 0.m(2) K x 0.6636(9) 0.64|0(12) one set of 24 Ulso. r9(2) 13(3) those of L6hn & Schulz(1968), wherein a refinement of a hauyne from Monte Somma, Italy gave an R Q 8(€) 0.30(2) ca 0.7008(8) o.zms(s) index of 0.082. In addition, the presentresults are Ubo. 32(2) 25(3) in contrastto those found for noseanand lazurite; Ca 8(e) 0.540) N8 0.73?4(5) 0.7r€2(8) their structurescontain two setsof 2a $) positions ulso. 17(?, 18(2) for framework oxygenatoms, and the tempera- the I 8(e) 0.1e(1) 0.4657(9) 0.4669(11) ture factors for the Al and Si atoms are of similar u"qulu 50 45 but larger magnitude than those in hauyne (Hassan 8(o) 0.75 o.s72(24) 0.6S(24 et ol. 1985,Hassan & Grundy 1989). Ulso. 16(11) 1,1502) The positions of the interstitial atoms were exa- mined on electron-densitysections and by least- 'Ueqqp.= 1/3(U11+U22+U33) 126 THE CANADIAN MINERALOGIST

TABLE5. AN|SOTROP|CTEMPERATURE-FACTORS* (A2x 103 ) FORHAUYNE All the peaksfor the 02 qiteoccur at the cornersof AT2S AND153 K a cube with edgesof 1.84. The 02 site (x : 0.60) group. Urt u2 ugg u'tz Utg u2s correspondsto the oxygenatoms of the SOa When the 02 $ite is included in the structural model, AI 293 K 8(3) e(2) e 0 n the resulting difference-Fourier map was found to 153K 4(2't 90) e 0 n 0 be featureless,which indicatesthat the small electron- sl 2gt K 9(3) 10(2) 10 0 densitypeaks (x : 0.40) representresidual density 153K 7(21 5(1) 5 0 0 293 K 15(3) 23(3) 30(2't 12(21 1(2) 2(3) from equivalent02 sitesbelow. 153K 14(3) 1e(3) (41 12(21 1(3) I (3) The calculated and observedstructure-factors for s 293 K 50(5) 50 50 -10(4) -10 -10 the reflections 110and 200 show large disagreements. 150K 45m 45 45 "12(41 The measuredintensity for thesereflections seems reasonable,but they could be affected by extinction; 'u = - thesereflections thus weretemporarily removedfrom t| ete tU1 /? + urrl? * UsCP r 2udhk + 2UBht + 2u2s!

TABLE6. INTERATOMTCDTSTANCES (A), ANGLES (o ), ANDVALENCE SUMS (v.u.) FOR HAUYNE

153K 293K 153K

AlO4telrahedron Atol 4x 1.741(5) 1.742(51* si-o1-Al 14e.3(3) 14e.7(3) o1-ol 4x 2.514(7) 2.815(6) osi 12.0 12.4 2\ 2.90.2(t) 2.W2(7' @4 12.9 11.6 Mean01-Ol 2.W 2.U4 Arlsi€ 1.670 1.670 SO4group 01-Alo1 4x 107.8(2) 107.8(2) s.o2 3x 1.4{'0(1 1) 1.447(sl 2x 112.5(2) 112.8(2) 1x 2.a92(15) 2.076(13) Mean01-Al.ol 109.5 109.5 Mean S€2 1.633 1.d)4 SlO4tetrahedron st-ol 4.x 1.sse(5) 1.597(4)r* 02€€2 3x so.o(6) €8.8(6) 01-ol 4x 2.566(4 2.564(6) 3x 120.0(7) 120.0(7) 2x 2.@(7) 2.6e5(6) Mean O2-SO2 105.0 144.4 MeanOl€1 2.610 2.608 Bond-valence sums o1€l€1 4x 106.8(2) 106.8(2) 'N=4xO.72=2.88v.u. 2x 115.1(2) 115.0(2) '*Sl = 4x1.12 = 4.49v.u. Mean01€lO1 109.6 109.5 THE CRYSTAL STRUCTURE OF HAUYNE t27

the C3 site, but the Ca atom could be at either of x:y: 0.34 the A and C3 sites. The ranges for the relevant cation-oxyggn dis- tancesusuqlly observed are: K-Q: 2.6-2.9 A, Ca- O:2.2-2.44, andNa-O:2.2-2.5 A (BIDICS,l98l). When thesedistances are comparedto the distances betweenthe C sitesand framework oxygen atoms (Table 7), the results confirm that the K atom occupiesthe Cl site, but the Ca and Na atomscould occupyeither the Q or the C3 site. In sodaliteand basicsodalite (I{assan & Grundy 1983,1984), the Na atom occupiesa position similar to the C3 site in hauyne;if the C3 siteis occupiedby Na atoms,then ffi the Ca atoms presumablyoccupy the A site. The scatteringcurves for the respectivecations were used in the structure refinement to determine the X=V:0.66 occupancy factors for each of these sites. The occupancyvalues (Table 3, column 5) are in satisfactory agreementwith the chemical composition (Table 3, column 4), and resultedin a reduction of the R factor from 0.037 ro 0.036. Although this decreasein the R factor is not significant at the 0.05 level accordingto the Hamilton test, the agreement with the chemicalcomposition and the satisfactory bond-distancesthat result give confidencethat the model is essentiallycorrect. The occupancyof the Cl, Q, and C3 sitesby K, Ca, and Na, respectively, alsois consistentwith the bond-valencesums (Table 7). The final R index for the structure at 153 K is 0.039;if we includereflections 110 and 200,the R value is 0.047. Except for smaller temperature- factors, the 153K structure is not significantly differ- b ent from that at 293 K (Tables4, 5, 6). The structural parametersof the framework are similar (Iable 6), but differencesoccur for structural parameters associatedwith the interstitial atoms (Table 7). A \ copy of the tables of structure factors is available at a nominal chargefrom the Depository of Unpub- lished Data, CISTI, National ResearchCouncil of Canada, Ottawa, Ontario KIA 0S2.

DISCUSSION

Ldhn & Schulz(1968) reported on the presenceof a SOagroup in hauyne. It occupiestwo positions that are rotated 90' with respectto eachother; with

(001) section calculatedwith the O2 site (e = 0.60) "\ removedfrom the structural model (R : 0.051).The Frc. l. Difference-Fouriermaps: (a) (001)section through two largepeaks v/ith coordinate(x, x, x), x: 0.60,cor- the 2(a) site (z = 0.5), calculatedwith the S atom respondto oxygen atoms of the SO4group; the two removed from the structural model (R = 0,067), show- smallerpeaks (x = 0.,f0) indicate small amounts of elec- ing that the S atom is not at the 2(a)position; O) (001) tron densitythat are residualsfroqr equivalent02 sites sectionthrough an 8(e)site (e = 0.47) showingtltp loca- below. Contour interval:0.5 e/i+3.The (x, /) coor- tion of the S atom. Contour interval = I e/A3. (c) dinatesare the sameon all maPs. t28 THE CANADIAN MINERALOGIST

TABLE 7. CATONOXYGEN DTSTANCES(A) AND VALENCESUMS.* tv.u.) FOR HAUYNE trostatically neutral; they have excesspositive charge,

r53K AK which may be balancedby OH- ions (Table 3). The presentrefinement indicates about 1.5 SOaper cell, C101 3 x 2.765(4) 2.78!14) 3 x 0.07 0.17 0.11 SOn -O1 3x 2.995(5) 2.3S2(6) 3 x 0.(g 0.t0 0.06 so that 75Vo of the cages are occupied by -[O'onsl' 3\ 2.457 i x 0.17 o.42 0.27 groups and the other 25t/opresumably contain OH I 0.50 '1.3:t 0.78 groups. The OH group can reasonablybe assumed O2 1r 1.01804) 1.04903) sx 2.463m 2.45716) to be at a S site whereit is vacant; this position would "S allow one OH per cage. C241 3r 2.sll(5) 2524(41 3x 0.14 0.35 0.2 .Ol 3x 2.871(6) 2.864(5) 3t 0.06 0.14 0.09 With the K atom at the Cl site, the cagecannot -lO onsl' 3x 3.0s I x 0.M 0.m 0.06 accommodatea SOo group becauseof the short r 0.64 1.56 0.S Cl-O2 and Cl-S distancesthat would result (Table .lo2'sdla€dl. rx 2rs 1 x 0.4 1.O7 0.6S : 1.04 2.U t.6t 7). In this case,the cagemay contain one OH at a 02 1 x r.600(15) 1.636(13) vacant S sire(Cl-[O'] in Table 7). The satisfactory € 3x 3.Cl36(6) 3.033(5) bond-valencesum that results for the K atom (Table c3ol 3 r 2.372(5) 2.386(4) 3x 0.20 0.50 0.32 7) confiims that the Cl siteis occupiedby K atoms. Ol 3 x 2.88(5) 282(4) 3x 0.06 0.14 0.@ The is much 02 for if .42 1x 2.204(15) 2214(13\ 1 x 0.33 0.80 0.61 C2 site too closeto a bond; t t.tl 1,44 0.92 this site is occupied,then the cagemay contain one -s 31 3.634(5) 3.604(4) Vdo@ Suro (v.[) OH group, which may be located at the S site

Bord-€lm@ sro tor O1: (C2-1[O'l in Table 7). A cage may have an SOo group and have one of the possiblefour C2 posi- FomAlardSl 0.2+1.12=|,Uv,u, F@KonCl +0.17+0.10-2.11eu. tions occupied, becauseone oxygen atom of the Fom Ca on C2 + 0.22 1 0.@ - 2.15 v.u. SOagroup could move to the [O2'] position to give - Frcm Na on C3 r 0.20 { 0.06 2.10 v.u. a (A-lO2' ) distanceof 2.ll A, qlmparableto the observedC3-O2 distanceof 2.21A (talte 7). Four . lo'l rept@dr ths oxygsn dom ot ths OH g@p o a @@m A dtC aid [O2,] @pr@rr€ C3 positions in a cagecan be occupiedif the cage anadju$€d 02p6il@ (@ton) contains a SOogroup in view of the C3-O2 distance (Table 7). A simplified charge-balancemodel, similar to that the sulfur atom at a2(a) position, this geometryleads for lazurite and nosean (Hassan& Grundy 1989, to a regular te[rahedral group with a S-O bond Hassanet al. L985)can be used to rationalize the length of 1.52 A. They suggestedthat the intersti- crystal chemistryof hauyne. A net residualcharge tial cations force the SOagroup out of the above of -3 v.u. can be assignedto the 12 framework oxy- position; their suggestionis confirmedin the present gen atoms that form the cage.This net chargecan study. They too found two cation sites,which cor- be neutralizedif the cagecontains [Na3Ca.SOo]3+ respondto the Cl and C2 sitesof this study. This clusters.The occupancyfactor for the S site indi- presentwork showsthat the sulfur atom is at the 8(e) cate$that [Na3Ca.SO4]3+clusters make up 75r/oof position instead of the 2(a) position as in noseanand the structure,and this accountsfor 4.5 Na, 1.5 Ca, lazurite; however, the oxygen atoms of the SOo and 1.5 SOoatoms per cell. As this is the number group occupyonly oneset of 8(e)positions. Because of Na atoms and SOogroups shown by the refine- of the rigidity of the SOr Broup, the oxygenatoms ment, all ofthese ions havebeen accounted for. In are expectedto be displacedfrom the body diagonals an asymmetricalenvironment of the cationsin a cage of the cell, as in basic sodalite (Hassan& Grundy (1.e., three Na and one Ca in a cage), the Ca2' 1983),but this effect could not be incorporatedin cationwould forcethe 56+cation off the 2(a)posi- the presentstructural model. tion, as indicated by the structure refinement. The short S-S distanceof 0.88 A allows one sul- The remaining2590 of the cagespresumably con- fur atom per cage. The geometry of the resulting tain [KrCa.OH]3+ clusters,with a vacant K atom, SOogroup is;rot typical (Table 6). The S-O2 dis- which accountsfor one K, 0.5 Ca, and 0.5 OH ions tanceof2.08 A is longerthan rhe S-O bond expected per cell. Theseresults give an overall composition for the SOogroup, but this dislancecan be short- of Nao.rCa2.1Kr.0[Al6Si6O24](SOrr.5(OH)0.r,which enedto the averagevalue (1.60A) if one of the four doesnot disagreesignificantly with the chemicalfor- 02 atoms, [O2'], is placedon an 8(e)position with mula (Table 3) or with the results of the present x : 0.5673instead of r = 0.5972:then the result- structure-refinement.If only [Na3Ca.SO4]3*were ing C2,-lO2') distancewoFld be a reasonableIength present, the composition would be of 2.ll A insteadof 1.64A (seeTable 7). The small Na6CartAl6Si6O24l(SOr2,which is the ideal formula amount of electrondensity (0.19 electron,/site)for for hauyne. If [KrCa.OH]3+ were to occur exclu- the 02' position is too small to be observed. sively, the composition would be The chemicalformula of Ldhn & Schulz (1968) KaCa2[Al6Si6Oza](OH)2,which is as yet unknown as and that obtainedfrom this refinementare not elec- an end member. THE CRYSTAL STRUCTURE OF HAUYNE t29

tTr ol*

Frc. 2. A [10] zoneelectron-diffraction pattern of hauyne.Ordering reflections (hkl, h+ k+ I = 2n+l) occur as weak spotsand diffuse, streakedsatellite reflections toward the edges(Philips CMl2, 120kV). Neithertype of reflections were observedin X-ray precessionphotographs.

The [Na3Ca.SOn]'* and [K2Ca.OH]3+ clusters to thosefound in sodalite;in particular, the frame- may order and give rise to weak ordering reflections work oxygenatoms occupy one set of Z(i) positions. (general:hkl, h+k+l = 2n * 1) and antiphase- The satellitereflections that are generallyobserved domain boundaries(r4PBs). TEM studiesreveal the in sodalite-group minerals arise from positional presenceof ordering reflections and diffuse streaked ordering of the framework oxygenatoms over two satellitereflections (Fig. 2) in addition to APBs in independentsets of Z(i) positions,as in noseanand hauyne(Hassan & Buseck1989a). The spacegroup lazurite. for eachdomain is P23, basedon the ordering reflections, and this spacegroup allows for sodalite-type ACKNOWLEDGEMENTS structures(Hassan & Grundy 1989). Although the hauynespecimen used in this study The hauyne sampleswere provided by courtesyof doesnot show any satellitereflections on precession Dr. Fred J. Wicks of the Royal Ontario Museum. photographs, suchreflections havebeen reported for This work wassupported by grantsfrom NSERC of other samples(Taylor 1967),and their origin is dis- Canada.Dr. J. Dave Embury, McMaster University, cussedby Hassan& Buseck (1989a,b). The tem- is thanked for his support and encouragement.We perature factors for the framework atoms and the also thank the two anonymousreferees and Dr. R. Al-O and Si-O distancesin hauyneare comparable F. Martin for helpful comments. 130 THE CANADIAN MINERALOGIST

REFERENCES a memberof the sodalite$oup. Actq Crystallogr. c47,827-832. BnowN,LD. & Arrsnuarr, D. (1985):Bond-valence parametersobtained from a systematicanalysis of Iro, T. & SADANece,R. (1966):On the polysynthetic the inorganiccrystal structure database. Acta Crys- structure of hauyne. Acta Crystallogr. 21, 455 tallogr. B4l, 2M-247. (abstr.).

BIDICS (1981):Bond Index to the Determinationof LdnN, J. & ScHur-2,H. (1968):Strukturverfeinerung Inorganic Crystal Structures.Compiled by Brown, am gestdrtenHauyn, (Na5KlCa)Al6Si6O24(SOrr.5. I. D., Weiss,C. P. and Wu, K. K., McMaster Neues.Jahrb. Mineral. Abh. 109,201-210. University,Hamilton, Ontario, Canada. Mor.ruoro,N. (1978):Incommensurate superstructures Cnourn, D.T. & Memt, J.B. (1968):X-ray scattering in transformationof minerals.Recent Prog. Nat. factors computed from numerical Hartree-Fock Sci.Japan 3, 183-206. wave functions. Acta Crystallogr. A24, 321-324. Searmo, H. (1961): Strukturbesonderheitendes HessaN,I. & Busrcr, P.R. (1989a):Cluster ordering Hauyngitters. Z. Krbtallogr. ll5, 132-140. and antiphasedomain boundaries in hauyne.Caz. Mineral. 27, 173-180. Scuurz,H. (1970):Struktur und Uberstrukturunter- suchungenan Nosean-einkristallen.Z. Kristallogr, & - (1989b):Incommensurate-modulated 131,114-138. structureof nosean,a sodalite-groupmineral Am, Mineral. 74.394-410. Srgwenr,J.M. (1976):The XRAY 76 system.Com- puter ScienceCenter, Univ. of Maryland, College & Gnurov, H.D. (1983):Structure of basic Park, Maryland, Tech,Rep. TR-M6, sodalite, Nar[Al6Si6O2](OH)2.H2O. Actq Crystal- logr. C39,3-5. Tevlon, D. (1967):The sodalitegroup of minerals. contrib. Mineral. Petrol. 16, 172-188. & - (1984):The crystalstructures of sodalite,Na6[AI6Si6O2a](OII)2,H2O. Acta Crystal- TsucHrve,N. & TerEucnr,Y, (1985):Fine textureof hauynehaving a modulatedstruc.lJre, Z, Kristallogr. & - (1989):The stucture of nosean, 173,273-281. ideallyNas[Al6Si6O2a]SOa.H 20. Can. Mineral. 21, 165-172.

-, PrrrnsoN,R.C. & Gnurov,H.D. (1985):The ReceivedApril 24, 1990,revised manuscript accepted structureof lazurite,ideally Na6Ca2[A16Si6O24]S2,August 11,1990.