Canadian Mineralogist Vol. 13, pp. 168-112(1975)

CRYSTAL STRUCTT'RES OF THE CHALCOPYRITE SERIES*

S. R. HALL Mineral SciencesLaboratories, Canada Cenfte for Mineral and Energy Technology(Mines Branch), Departmentof Energy,Mines and Resources,Ottawa, Catrada, KIA AGI

ABsrRAcr atoms at the interstitial sites of a sphalerite-like A comparisonof the crystal structures of the arrangement of sulphur and metals, rather than mineralschalcopyrite, CuFeSz ftIall & Stewart1973), on metal-substitution or sulphur-removal which talnakhite, CueFesSl6(Hall & Gabe 1972), mooi- are the other two structural mechanisms pos- hoekite CusFes$s(HaI & Rowland 1974) and,hay- sible for this type of cubic close-packedarrange- cockite CuaFe5Ss(Rowland & Hall 1975) is made. ment of atoms. On this basis, the compositional Tho metal-rich minerals are related to chalcopyrite data determined by electron-microprobe meth- by additional metal atoms located at interstitial sites. ods (fable 1) were consideredin terms of an in- and have structur€s consistent with stoichiometric tegral number of sulphur atoms. The resulting compositions. The interstitial metals can tre de- chemical formulae contain an integral number scribed iu terms of metal-coordination octahedra standard which vary in size according to the packing ar- of metal atoms, within the estimated rangements. deviation of the probe measurements. This was the ffust evidence that the chemical formulae for 1974). INrnooucrroN these minerals were stoichiometric Glall Interstitial metals The crystal structure of chalcopyrite, CuFeSr, was first investigatedby Burdick & Ellis in 1917, The principal structural aspect common to and has been studied by a nr:mber of workers talnakhite, mooihoekite and haycockite is the since, most recently by Hall & Stewart (1973). presence of extra metal atoms located at inter- In the last few years three new minerals closely stitial sites of the ccp sulphur lattice. Minerals related to chalcopyrite have been discovered. related in this way are sometimes referred to as They are talnakhite CusFeesro(Cabri & Harris "stuffed derivatives". In these structures each 1971), mooihoekite CusF€eSroaod haycockite additional intentitial rnetal atom has a first- CqFeoSr (Cabd & Hal|L972). The crystal struc- order tetrahedral coordination to sulphur atomsn tures of these minerals have been determined at interatomie distances of about 2.3A, and a (tlall & Gabe 1972; Hall & Rowland 1974; second-order octahedral coordination to "reg- Rowland & Hall 1975), and this paper zum- ular" metal atoms, at about 2.7A. The proxi- marizes the results of these studies and identi- mity of tle interstitial metals to the surrounding fies their relationship to eash other. "regular'n metal$ is oipificant in view of the fact that the metallic Fe-Fe and Cu-Cu distances Drscussrorv are only 2.48 and 2.56A respectively. Though these distances do not give rise to purely metal- The crystal data for chalcopyrite, talnakhite, lic properties for these minerals, the resulting mooihoekite and haycockite are su'nmarized in Table 1. For these minerals the relative unit cell volumes V/V ncreasr, with an increasing metal- TABLEl. CRYSTAL0ATA 0F CIIALCoPIRITE-LI(EI'IIHERALS to-sulphur ratro. Z is tle number of pseudo- Ptabe fu cubic sphalerite-like cells which form the basic At. U Cu 25.1e0 2) 27.19(lo) 26.41(ro) 23.s6(15) lattice Fe,Nl a.a05) 24.74(151 26.14(14) D.46(ml of these minerals. The V/Z values pro- 49.63(25) 48.1603) 47.r6(A) 46.e8(25) vided the first indication that the corrpositions EowLa CuoFegsr6 CugFesSs5 CugF€95r6 CusFe1q515 of these ,minerals were metaldch ratler tlan SWae @ora? fizd fibt ila, v2.2r,2* sulphur-poor: They also provided early evidence (A) 5.2890 ) r0.s93(3) r0.58s(5) 10.70s(5) b" 5.2890) lo.5s3(3) 10.585(5) 10.734(5) that the basic structural mechanism for 10.4A0) 10.593(3) 5.38:r(s) 31.60(15) these 8424 minerals was based on the addition of metal vtz'(Arl I 45.8 148.6 150.8 151.5 '1614 Ttb8iq 694 rcfl. 528refl. refl. 2890fsfl. R-tal,w all dsta 0.086 0.205 *Mineral Research Program - Sulphide Research 'lss. tJla6' 0.051 0.047 0-t4 Contribution No. 90. 0.031 168 CRYSTAL STRUCTURES OF THE CTIALCOPYRITE SERIES 169 second-order metal-octahedra are a most im- TABI.E2. 5ETECTEI}AVEMOE IUTERAMfiIC.DISIANEE5 portant'component in relating the chalcopyrite- Cistanse would then be half the length of of the sphalerite-like lattice due to the addition the pseudo-cubic cells which make up eaoh of interstitial metals is conveniently described in struciure (V n Table 1 gives the number of terms of the second-order octahedral coordina- these cells). tion surrounding each interstitial metal site or The metal-octahedra coordinating each M', each interstitial metal site. For the Mo, M+ and M* site are referred to as "ideal", "potential" oovacant'nn sake of brevity each of fhe "regular" metal atoms "isolated" lad "linkgd", tespectively. at the vertices of the metal-octahedra is denoted A summary of the metal-metal distances for by aa M; interstitial sites which are unoccupied, the different structures is given in Table 2. T:he by an Mo; occupied interstitial sites which are similarity of. the

tol

'29 cp 557 mh 1r

Frc. 1. The crystal structgres of chalcopyrite (cp), talnakhite (ral), mooihoeklle (mh) and haycockite (hc) aro shown scfiematically in terms of sfraterite-type "cubes" of metals and sulphurs. (detailed in the upper-left corner), and in terms of interstitial metal-octalredra. The a, b alord c dimensions of the "cubes" are given (in angstroms) for each structure. 170 THE CANADIAN MINERALOGIST

"linked". That is, LM-M+ 2 are greater than an antiferromagnetic structure from its struc- .This is because the addition of the tural similarity to the ofher .minerals in the intentitial metal into an "isolated" site is facili- S€fI9S; tated by an outward movement of the M-atoms The antiferromagnetic i+=zd stucture of chal- which is not prevented by an opposing distor- copyrite arises from the two Fe(4b) atoms being tion from adjacent occupied metal-oCtahedra. tetrahedrally (with ,,vacanf, arranged two Cu(4a) atoms) The contraction of all surrounding about each sulphur atom and having opposed octshedra is ryitnessed by the relatively smaller moments aligned along the c-axis. The magnetic distances. For structures containing coupling between the Fe atoms is via tle sul- only isolated metal-octahedra, the contraction phur atom and is generally referred to as an of adjacent vacant metal-octahedra enables the Anderson superexohange interaction. The sul- repeat unit of the sphalerite-like lattice to re- phur coordination-tetrahedra of two irons and main essentially unchanged. The 1M-Mr7 two coppers also form significant portions of distances show tlat this is the case for all lat- the structures of talnakhite and mooihoekite, tice direstions in talnakhite, the r and y direc- and this is expected to account for the antiferro- tions in mooihoeki.te. and the e direction in hav- magnetic aspect of these minerals. cockite. When two'ooccupied" metal-octahedia aro adjacent (i.e. "linked") expansion in the di Thermal motion rection of the sommon M atorn ocsur without The relative rnagnitude of the thermal motion an over-all expansion of lattice in this direction. for the Cu, Fe and S atoms in these minerals The increased energy required for lattice expan- is remarkly consistent. The average isotropic sioq results in significantly srnaller temperature factors, , summarized for than distancesfor these directions. these atoms in Table 3, show that the thermal This is the case for the e direction of mooihoe- motion of the iron atoms is consistentlv lower kite, and the r and y directions of haycockite. than that for copper atoms. This was also found The extent of the lattice expansion due to the to be the case for cubanite CuFezSls(Szymanski adjacent interstitial metals san be gauged by the 1974), The relative difference for Fe and Cu difference between the two distances atoms may be expected for several reasons: the for mooihoekite and havcockite. stronger covalent interaction between iron and sulphur over copper and sulphur, as Magnetic structure witnessed by the consistently shorted Fe-S distances over The magrretic structure of chalcopyrite has Cu-S (see Table 2); the magnetic exchange in- been established as antifemomagnetic by Don- teraction between the Fe atoms but not the Cu n.ay et al. (1958) using neutron diffraction tech- atoms; and lastly the proposed higher effective niques. Mdssbauer and magnetic susceptibility charge of Fe atoms over Cu atoms (Ilall & studies of talnakhite and synthetic mooihoekite Stewart 1973). lt should be stress€d, however, have shown them to be predominantly antiferro- that while the .r-ray diffraction analysesprovide magnetic (Iownsend et al. 1972). Haycockite the relative magnitudes of the thermal motion of has not been extracted in sufficient purity or these atoms to a reasonabledegree of certainty, quantrty, nor has it been synthesized to enable they provide little insight into the cause. Never- magnetic studies..However, it is expectedto have theless, in the structural study of these minerals

TABLE3. AIOIIICSITES, AYERAEI TENPERAWRE FACMRS ANO @ORDIMTTOH C@rdlnatlon: T tR. lrcgutar TBP. trJgonal blpyfeldll D. distorted

Chalaop!?tte taLwtt6 ,Ioatlpeklte Eq!@'lrtta

r_13.d Atm coord- r43n Atm Coofd- Pzzz"Ato .g, 518 Type lnatlo Slte Type lnatlon Site Type JnatJol Slte Type' pl I[:i: ul (44) cu r.54 IR.T. cu l,58 filtfri !AQL) (8a) J:df. U{gl,ff f:ff IEI;]. Fe 0.95 Fe 0,89 S s 1.00 IR.T. M:l(l2d) Fe 0.78 R.T. ll3(4t) cu l.4l IR;J.T Fe 0.73 M4(8d) Cq 1.54 IR.T, M(zf) Fe 0.95 '14 Cu l.g7 Sl (4o) s I .03 D.I3P. M5(lo) Fe 0.93 Fe 0.87 s2(8d) s 0.95 rR.T. M5(lb) Cu 1.46 Cu 1.68 lfl(la) Fe 0.75 l! t I cu 1.52 l8(la) Fe 0.75 Fe 0.7t sr(8") s r.04 1R.T. Fe 0,81 s2(4r) s 0.78 D,TBP. Fe 1.24 s3(4") S 0.97 D.TBP.sl (41 s 1.0 sr(aL s l.16 s 0.87 lA rent rcfln@nt of tfi6e data lnrcltlig mtll{rdertry 2soall t€trrgoml psodec€ll 66d eAll for llte sj@tr? aordlmtlon polyhedra !E lr€gutar rd mt llsted {djacent lnteFtltlal etal slt€ CRYSTAL STRUCTURES OF THE CHALCOPYRITE SERIES t7r the isotropie temperature factors did provide, IABLE 4. POMERDIFFRACTIOT DATA' along with the "regularily" of. the metal eo- ordination polyhedra (see Table 3), an inpor- ll0 7.490 I I llo 7.485 4l 004 7.907 tant guide to determine the metal-ordering. | 001 5.383 I I 2oo' 5;2 - 1 | 209 -C.t97 r 1' 20 0 5,367 02 z 5.w. 0lI 4.717 I 20 2 5.070 Metal-ordering 112 4.325 1 ll t 4.370 2 02 4 4.441 00 8 3.954 The metal-ordering in chalcopyrite is deter- zAt 3.774 3 220 3,7!5 2 220 3.742 | 22 2 3.86 mined unambiguously from electron-den!ity 310 3.350 t 310 3.347 3 02 I 3.182 considerations(Hall & Stewart 1973). However, ll2 3.038 100 222 3.858 100 221 3.073100 22 6 3,077100 312 2.831 I 311 2.43 2 for the more complex structuxesof mooihoekite, 002 2.69t 6 04 0 2.681 5 2M 2.644 9 400 2.648 u 400 2.646 13 & 0 2.676 4 talnakhite and haycockite this is not feasible due 004 2.606 5 @12 2.636 5 l 12 ?.533 I to the rapid rncrease of the ratio of the number 3N 2.497 | 2210 2.428 2 Mt 2.375 "l of refinable atomic para,meters over the dif- 332 2.258 | 331 2.264 2 04 8 2.220 1 fraction data available. The resulting decrease 222 2.1A5 | 422 2.162 1 421 2,167 | 'i5 314 2.077 | 312 2.09S I ,U 0 l.ms in electron-density resolution is accentuated by 402 t.*7 47 0412 1.880 25 220 1.870 20 440 l 873 s3 440 1,471 23 4012 1.478 2l the superstructure nature of these minerals, and 204 1.856 36 332 t.&10 r 223't.6tg12 26 6 1.6t5 il their propensity for integral .twinning. Both a 312'n6 I.593 29 622 t,597 28 621 1.598 24 62 6 1.612 l 575 14 2218 1.594 12 theso factors made the measurement of diffrac- 3t3 I.581 I 224 1.5t9 3 444 1.529 3 442 1.536 3 4412 r.$9 3 tion data relatively difficult and as a conse- t7t 1.442 | quence, meant that electron-density considera- 004 1.346 3 08 0 t.342 4 NO | ,322 6 800 t.324 7 900 1,323 7 80 0 1.338 3 tions could not be used alone to identify metal- 008 t.303 3 0024 t.3t8 4 623 t.224 I 66 6 1,229 3 types An identification approach evolved in the 332 1.212 6 662 1,215 t2 561 1.215 4 2618 1.221 5 316 t.205 ll 6218 t.219 4 study of these structures that was based largely 420 t.l8:) I 4M 1.200 I 0812 1.196 I 404 1.179 I 804 |,184 2 802 1.187 | 0424 1,183 I on the relative thermal motion of the metals and '2442@ 't.O771.169 I 480 1.183 '9I 4024 1.142 1 17 449 1.081 2l 444 I.093 4a12 1.492 9 the regularity of their metal polyhedra. A sum- 228 1.069 9 482 1.083 t8 84t2 1.090 7 M24 t,$U. 10 mary description of the metal tetrahedra for 2.5 1.035 3 210't02 6 t.032 4 6 1.030 3 these structures is given in Table 3. This shows 666 I.019 3 663 1.024 4 6618 1.026 3 512 1.017 9 1022 1.0t9 9 r02l 1.0r9 7 2230 1.016 4 tha! in general, the iron tetrahedra tend to be 336 r.013 6 ]ll0 1.004 5 804 0,943 12 88 0 0.947 5 "regular'o whereas those containing a copper 440 0.935 7 880 0.936 14 880 0.936 5 0824 0.940 7 atom are not. The joint agreement of a low 4M 0.9n V 8024 0,99 6 (B) value and a "regular" tetrahedron was i Pdder dlffractJon dat! generatad tr@ n@wad slngle crystrl lntensltl6 lslng the prcgrM PoIJGEN(Hall & szJ@nskl 1975), Pohder intensltles ra used in a number of casesto identify iron atoms, 'lnclude lGland Klz [email protected] and .3s@ negllgJble absorptlon. though tlere were exceptions. For this reason it -Y" should be stressedthat this procedure is large- ly ernpirical, and the metal-ordering reported and iniensities determined from the measured for these structures is by no means unequivocal. diffraction data of chalcopyrite GfaU & Stewart There is no question, however, that the metal- 1973), talnakhite (Ha[ & Gabe 1972), mooihoe- ordering proposed for talnakhite and mooihoe- kite (Hall & Rowland 1973) and haycockite kite has a hlgh ccrrelation with both structural (Rowland & Hall 1975). and magnetic considerations.In th,e caseof hay- cockite, the lack of magnetic data" the much AcrNowr-BPcEMENTS lower atomic resolution of the x-ray diffraction data, and the general irregularity of the metal The author wishes to thank the numerous col- tetrahedra makes the assignmentof metal types leagues in tle Mineral Research Progran wbo less reliable. participafed in these structural studies, and who provided constructive comments to this review. Powder patterns lrom single-crystal data gimilffity fhe of the r-ray pofder patterns of REFBETYCES talnalhite, mooihoekite and haycockile to that of chalcopyrite has been discussed by Cabri & BuRDrcK,C. L. & Etr,ts, J. H. (1917): The crystal structure of chalcopyrite determined by .r-rays. H^11 (1972). In particular, for mooihoekite and gg,2518'2525. haycockite it is difficult to obtain a characteris- J. Amer. Chem.Soc. L. J. Her.r, S. R. (1972): Mooihoekiteand powder pattern to problems in obtaining CesRr, & tic due. haycockite, two new copper-iron sulphides, and sufficient pure material. Besause of the consider- their relationship to chalcopyrite and talnakhite. ably higher precision of the single crystal dif- Amer. Mineral. 57, 689:108. fraction data, reliable powder patterns for these & Hennrs, D. C. (1971): New composi- minerals may be sonstructed for the measured tional data for talnakhite, Cura(FeNi)reSss,Econ. diffraction maxima. Table 4 gives the d-spacings Geol. 66, 673-675. 172 THE CANN)IAN MINERALOGIST

DoNNAy,G., CoRLIss,L. M., Donr*ev, J. D. H., tern generation from single crystal data. Winter Er.uor:r, N. & Hesrncs, J. M. (1958): Sym- Mtg, A.C,A, Charlottesville, Va. metry of magnetic structures: the magnetic atruc- RowrANo, J. F. & HaLL, S. R. (1975): Haycockite ture of chalcopyrite.Phys. Rev, l1-z, l9L7-1923. CuoFe5S6:a superstructure in the chalcopyrite Hu,r-, S. R. (1974): The chalcopyrites:stoichiome- *ries. Acta CrysL fln press). tric minerals related by interstitial metal atoms. SzyueNsrr, L T. (197$: A refinement of the struc* Abstr. tr D-L, Internat. Union Cryst. Conf., Mel- ture of cubanite, CuFer$. Zeits. Krkt. 140, 2L8- bourne. 225. & Gess, E. l. (1972): The crystal struc- TowNsrNo, M. G., Horwooo, J. L." Her-r,,S. R. & ture of talnakhite, Cu1sFe1uS"2.Amer, Mineral. Cernr, L. L (1972): Mtissbauer,magnetic suscep- 57, 368-380. tibility atrd crystallization investigations of & Rowr-u.ro,J. F. (1973): The crystal CuaFeeSe, CulaFetrSp and CueFeeSrs, I.A.LP" structure of synthetic mooihoekite, CueFeeS,u. Confr, Proc. 5, 887-891. Acta Cryst. B29, 579-585. & Szvuexsrr, J. T. (1975): Powder pat- Manuscriptrecel,ved. February 1975.