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 radi- ation 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 reflec- tions 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<h,k,l< 13 11 Totalno. of lnlensitles 1&r9 1087 No.of uniquereflectlons 329 215 'r33 No.of non-equlv.lFol > 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<o.qlrz.gslAoSi6o24l(Sod1.56€OH)j.0s (e)Reflnement: (N"s.osO"e.eeh.erbe.relAoSi6O24l(SO4) j.5(?OH)r.a6 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 tempera- ture 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.