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Home , Hanksite, Searles Lake

American Mineralogist, Volume 58,pages 799-801,1973

The GrystalStructure of

Tnrlnlnu ARAKr,l,lNn Tlson Tntrx Departmentof Geologyand Geophysics,Uniuersity of Minnesota, Minneapolis, Minnesota 554 5 5

Abstract

Hanksite, NaaK(COg)r(SOn)"C1, from , California, gave the space group P6s/m and the unit cell constants a - 10.465 and c - 21,191 A. Its structure was solved by three-dimensional Patterson synthesis and subsequent Fourier methods. The atomic co- ordinates and isotropic temperature factors were refined by full-matrix least-squares to R = 6.45 percentfor 1159reflections. The structure is characterized by chains of Na and K octahedra running parallel to the c-axis. These chains are connected by carbon and sulfur coordination groups,

Introduction cell dimensionsare in good agreementwith those ( The and the conditions of occurrence first reportedby Ramsdell 1939). of hanksite,NazsK(COe)2(SO4)ecl, at SearlesLake, Three-dimensionalintensities were collectedby a California, and the system Na-Cl-SOa-COs-H2O, generalinclination (Santoro and Zocchi, 1966) dif- which includeshanksite, have been extensivelystud- fractometerusing CuKc radiationon a crystalfrag- ied by severalauthors (Eugster and Smith, 1965; ment mountedfor a-axis rotation. All 1268 reflec- = Hardie and Eugster, l97O; Smith, Friedman, and tions were measuredup to sin 0 O.9245and were Matsuo, 1970). The possiblecrystal structure of correctedfor absorptionusing the methodintroduced hanksite, however, posed interesting questionsdue by Burnham (1966). The spacegroup of P6s/m to the unusual cation ratios in its chemicalcomposi- was concludedfrom the systematicabsences in the tion and the identity of its morphology and space 00t reflections,from the inequalities between hkl group with that of apatite. andkht intensities,and from the N(z) testdescribed Simultaneouslyand independentlyof this study, by Howellset aI (1950). Kato solved the structure of hanksite on a In the Pattersonsynthesis several prominent peaks obtained from the same locality, and published a were observedat the approximatelocations of: brief summaryof his results(Kato, 1972). UV : 0l/2,l/20,l/2l/2 atW : 0,l/6 and2/6 levelsand UV : l/6 2/6,2/6 l/6, 5/6 l/6, 4/6 2/6 Experimental at W : 0 and everyl/121h level. The unit cell dimensionsof hanksite,from Searles On the basisof theseobservations sulfur atomswere Lake, California,, as obtainedfrom precessionphoto. locatedtentatively at 2/6 l/6 l/12 and l/6 2/6 3/12, graphs and refined by a least-squaresmethod from and sodiumatoms at 2/6 l/6 3/12 and l/6 2/6 l/12 carefully preparedpowder diffraction data, are: a = and at inversioncenters. The validity of this model -+ 10.465 0.021,c = 21.191r 0.043A. Theseunit was tested with a weighted B-general synthesis (Ramachandranand Srinivasan,1970, pp. 80-ll9). 'prar-tt The test confirmedthe approximatelocation of sulfur uadress: Department of Geophysical Sciences, the University of Chicago, Chicago, Illinois 60637. and atoms and revealedthe sitesof all 'The chemical composition of hanksite is assumedto be other atoms. that reported by Pratt (1896) and confirmed by Ramsell Five cycles of full-matrix least-squaresrefinement (1939), as the specimenused in this study came from the wererun for 1159reflections (that is, all but 9 strong same locality and gave identical unit cell dimensions,This a{i : obtain composition was later verified by the absence of anomalous reflections above 0.25\ in order to temperature factors and peak-heightsin the least squares better atomic coordinatesand isotropictemperature refinement, factors.The scatteringcurves of K*, Na*, Cl-, O-, S

799 8OO MINERALOGICAL NOTES

Tesr.r l. Atomic Parameters and Isotropic Temperature Teele 3. X-ray Diffraction Powder Pattern of Hanksite Factors in Hanksite, NapK(COa)p(SOn)'Cl

Atom l{ x h k 1 d(obs) d(calc) Iotersity h k I d(obs) d(catc) Inretrsily u UZ ru.b0 10.60 2 4 03 2.158 2.Ls1 0 0 0 1.779(48) I 00 9.039 9.062 9 2.L46 2.L47 3 1 03 5.569 Na(1) 6 1/2 0 0 1.576(sr) 5.577 42 8 2.096 2.096 13 0 04 5.301 5.29a 53 I 2,O70 2.O70 3 Na(2) 4 2/3 .3757L (76) 1.819 (60) IO 5.229 5.236 103 2 2.Mt 2,O40 10 Na(3) 4 0 0 .326s2 (L6) (57) 1.6s5 l I 5.089 5.083 13 24 1.935 r,935 3 Na(4) 6 .34576(32) .14670(32) 714 2.174 (55) o 4 4.573 44 06 t.907 1.907 0 0 4,532 6.5 Na(5) 12 .r787C (22) (23) r 0tl r.884 1.884 2 .36173 .42s7t (rq r.889 (43) I 3 4.205 4.206 1.5 3 25 r.855 1.868 Na(6) 72 ,s2262(2r) .05337(22) .66098 (9) r.750 (4r) 0 5 3.843 3,840 54 L4 1.852 1.853 2 ct2 L/3 rl4 2.43s(s5) 3 3.8L2 3.8r4 100 318 L.423 L.824 4 O J. )JI 3.532 75 c 213 rl3 .s69s1 (3s) r.041 (109) 500 1.813 1.813 5 o 3.425 3.426 60 501 (1) L805 1.805 7 s 6 .2085r (r7) .35679 (J6) r/4 r.r75 (35) 1 3.383 3.383 t4 2Lt0 1.802 1.802 (2) 5 3.292 3.290 4 4L5 r.793 L.192 s 72 ,33869(11) .16831(rr) .40910 (s) 1.007 (31) (r) 0 L2 .59s60 (34) .40349 (3s) .s69SS(1s) L.374 (55) 2 3.259 3.260 o o 12 7,766 L.756 7 3.083 3.083 4L6 t.726 7.726 3 0(2) 6 .3ss90 (s6) .36881 (ss) 7/4 r,935 (85) 0 3.024 3.021 2.5 2 1.72I L.722 3 (3) 0 6 ,09251 (s4) .20129 (s5) Ll4 r.877 (8s) 6 2.930 2.92a 3 1.694 1.594 3 (4) 0 7 2,874 2.a7L I) L2 L,6J3 t.673 0 1-2 .19799 (42) .43019(43) .30711 (r9) 2.457 (70) (5) 0 6 2,787 2.785 0 12 .38977 (3s) .1134s (39) .3s672 (17) 2.077 (62) 72 10 1.628 1.628 2 I 5 2.665 2.665 (6) 11 ,. -^^ L.624 0 12 ,19609(37) .1ss37 (39) .39408 (17) (65) 1 7 2.621 rr'ozr 1.9s9 tz'oro r r.623 (7) 2 0 2.6ra I0 1.620 L,620 0 12 .44786 (39) ,32363(38) ,4rs7o (r7) 1.9s0 (53) 0 8 2.54t 2.543 5 L.513 1.613 2 0 (8) L2 .32292 (37) .08012(38) .46573 |f7) L.877 (62) I 0 2.5L3 2,574 9 2 1.509 1,509 2,5 FyWleg in parenthesee_ I are stmdard deui.ati.ore in tems of the I 1 2.496 2.497 11 L2 1.569 r.570 1.5 La6t decanaz plaees of dzbemined paLues. 2 3 2,452 2,455 1.541 L.542 10 I 2 2.446 2,446 10 1 3 2.367 2.369 space group: P63ln 0 6 2,295 2.296 and C arethose of Cromer 0 9 2.274 2.279 and Man (1968).The final Unlt cell: d = 10,465 t I 4 2.27r 2.27r 0,021 I c - t R value for the ll59 reflectionswas 6.45 percent. 0 1 21.191 O.O4SE The atomic coordinatesand isotropic temperature factors with their standard deviations are given in Table l. Na(2), is on the 3 axis and is surrounded by six oxygens and one to form a peculiar Description of the Structure co- ordination group. The carbon and sulfur atoms are Sodium has severalcoordinations in the hanksite in the usual triangular and tetrahedralcoordination. structure,as illustrated in Figure l. There is a chain A summary of major polyhedral interatomic dis- of four sodium,Na(3), (and two )octahedra, tancesis given in Table 2, and the calculatedpowder sharing faces, which runs along the 6, axis. There are six slightly distorted sodium tNa(t) and Na(6)l octahedrathat by sharing cornersform chains along o o.1 the 2, axis. Another sodium Na(4), is coordinated to four oxygenatoms at shorter distancesand to an oxygen and a chlorine at longer distances; it is sandwiched between sulfate groupS. One sodium, Na(5), is coordinatedto four oxygensin the horizontal and two in the vertical directions.The sixth sodium.

Trsrn 2, Summary of Polyhedral Interatomic Distances

Atoms Dlstances (A) Distances (E)

K-O 2.925(7)* c-o 1.280(4) t( Na-O 2.28 to 2.98 s-o 1.46 to 1.48 Na-C1 2,66to 2.9L n-n 2.38 to 2.42 Ox or" Qo Qcr *Figrr.s in parentheses aye standzzd. d-euiations, c-projection of the hanksite structure. (Carbon atoms not shown.) MINERALOGICAL NOTES 801 patternin Table 3. A list of observedand calculated HARDTE,L. A., lNo H. P. Euosren (1970) The evolution of structurefactors of hanksitehas been depositedat closed-basinbrines. . Soc. Amer. Spec. Pap. 3, the NationalAuxiliary PublicationsService. s 273-290. Howerts, E. R., D. C. PHrI-rrrs, rNo D. Rocrns (1950) The probability distribution of x-ray intensity, II' Ex- Acknowledgment perimental investigation and x-ray detection of center and symmetry. Acta Crystallogr. 3, 214-214. This study has been supported by a grant from the Na- Kero, K. (1972) Kristallstruktur von Hanskit' Natur',riss- tional ScienceFoundation. enschalten,59,269. Pnlrr, J. H. (1896) On northruptite; pirssonite, a new References mineral; gaylussiteand hanksite from Lake, San Bernardino County, California. Amer. I. Sci., Ser. 4, Bunvnlu, C. W. (1965) Computation of absorption cor- No.8, 123-135. rections,and the significanceof end effect.Amer. Mineral Revrcn.rxonen, G. N., eNo R. SnINrveseN(797O) Fourier 5r. 159-167. Methods in Crystallography. Wiley-Interscience, New Cnourn, D. T., lNo I. B. Mew (1968) X-ray scattering York. factors computed from numerical Hartree-Fock wave RAMSDELL,L. S. (1939) Composition, space group, and functions. Acta Crystallogr. A24, 321-324. unit cell of hanksite. Amer. Mineral. 24, 109-ll5' Eucsrrn, H. P., eNo G. I. Sr'rrrn (1965) Mineral equilibria Sewrono, A., eNo M. Zoccrr (1966) Multiple diffraction in the SearlesLake ,California.l. Petrology, in the Weissenbergmethods. Acta Crystallogr. 21, 293- 6,473-522. 297. Svrrrn, G. I., I. FnteouAN, AND S. Mlrsuo (1970) in Searles Lake, California' " To obtain a copy, order NAPS Document O2123 by crystallization temperatures Amer. Spec.Pap. 3, 257-259. remitting $1.50 for microfiche or $5.00 for photocopies, Mineral Soc. payable to Microfiche Publications, 305 East 46th Street, New York, N.Y. 10017. Pleasecheck the most recent issue Manuscript receioed,December 11, 1972; accepted of this journal for the current addressand prices. for publication,APril 4, 1973.