Solubility of Gallium in Sphalerite and Wurtzite At

Canadian Mineralogist Yo|.29, pp. 143-148(1991)

SOLUBILITYOF GALLIUMIN SPHALERITEAND WURTZITEAT SOOOCAND gOOOC

TEIICHI UENO Deportmentof Earth Sciences,Fukuoka University of Education,729Akama, Munakata, Fukuoka, 81141, Japan

STEVEN D. SCOTT Departmentof Geology,Earth SciencesCentre, University of Toronto, Toronto, OntarioMSS 3BI

ABSTRACT Yamato-74370(EH4) chondrite containsup to 5.8 wt.9o Ga (Nagahara& El Goresy 1984),and that from the (EH3) chondrite,up to 1700ppm Solubilitiesof gallium in sphaleriteand wurtzite were Qingahen (Woolum metal investigatedat 800'C and 900'C by means of phase- Ga et al, 1984).Sphalerite in a sul- equilibrium experiments.In the systemZn-Ga-S, the max- fide nodule of the Qingzhen@H3) chondrite con- imum solubility of Ga in sphalerite is 24,9 atomic 0/oat tains between2.05 and 3.10 wt.VoGa (Rambaldie/ 900'C and 16.3 atomic 9o at 800'C. In the systemZn- ql. 1986\. Fe-Ga-S, gallium solubility is more than2l.4 atomic Vo We have measuredthe solubilities of gallium in in wurtzite at 900oC.more than 15.6atomic goin wurzite sphalerite and wurtzite by synthetic phase- at 800'C, and more than 27.4 atomic 9o in sphaleriteat equilibrium experiments,and here presentresults on 800oC.The cell parametersof Ga-bearingsphalerite and the first study of the systemZn-Fe-Ga-S. Natural Ga-bearing wurtzite decreasedramatically with increasing Ga-bearing zinc sulfide, particularly that in gallium content. meteorites,commonly containsconsiderable Fe, so Keywords: gallium, solid solution, sphalerite, wurtzite, that this systemis of greaterrelevance than the Fe- cell parameters. free systemZn-Ga-S, which had previously been studied ar 900oc by Hahn et ol. (1955).

SOMMAIRE SranrlNc Mersntar-s ANDTHEIR SyNTHESIS

Nous avons6tudi6 la solubilit€du gallium dansla spha- Three elements(Fe, Ga and S), aIl of 99.9c/oor l6rite et la wunzite i 800oet 900'C en utilisant desexp6- better purity, and three syntheticmonosulfides (ZnS, riencesde synthCse.Dans le systemeZn-Ga-S, la sphal6- materials.ZnS rite peut contenir jusqu'd 24.9V0de Ga (baseatomique) FeSand GaS)were usedas starting a 900'C, et 16.3V0a 800oC.Dans le systdmeZn-Fe-Ga-S, was used as a commerciallyavailable white, pow- la solubilit6 du gallium dans la wurtzite est sup6rieurei deredreagent, in wurtzite form. FeSwas synthesized 21,40/od 900'C et 15.690i 800"C, tandis qu'elle est sup6- by reactingiron and sulfur in an evacuatedsilica glass rieured27 ,4a/odans la sphal6ritei 800oC.Les parambtres tube at 400'C for two daysin order to obtain initial du r€seaude la sphaldrite et de la wurtzite gallifdres dimi- reaction without bursting the tube, and tlen at 5@'C nuent de fagon dramatiquei mesurequ'augmente la teneur for five daysto obtain homogenization.The product gallium. en wasdetermined by X-ray powder diffraction @eKa radiation) to be troilite (FeS). (Traduit par la R6daction) The synthesisof GaS was difficult. Gallium melts Mots-clds: gallium, solution solide, sphal€rite,wurtzite, at 29.8"C, and its liquid does not mix with liquid parambtresr6ticulaires. sulfur, which melts at llgoc, becausea thin layer of gallium sulfide forms at the interface and inhibits further reaction. Despitethis, Klemm & Vogel (1934) INtnolucttoN managed to synthesizeGaS from elementsusing a V-shaped silica tube. Rustamov & Mardakhaev Gallium is found in nature in oxide, silicate and (1964)used an oscillation method to react gallium sulfide minerals (Johan et al. 1983, Bernstein 1986). and sulfur completely.Lieth et al. (1966,1967) syn- The main Ga-containing sulfide minerals are thesizedGaS by sublimation using a silica boat in renierite, germanite and gallite. According to Sheka a long silica tube. et al. (1966), the dominant host of Ga in sulfide ores Our method for synthesizingGaS was as follows. is sphalerite; the concentration of Ga varies between Gallium and sulfur in an atomic ratio of 1 to I were tens and hundreds of ppm. Some high values of gal- sealedin a 2O-cm-longevacuated silica glasstube. lium have been reported in a zinc sulfide phase in The sampletube was heatedfrom 200oCto 850'C meteorites. A zinc sulfide found in the in a furnacethat wasinclined at about 10'; the tem- t43 144 THE CANADIAN MINERALOGIST

peraturewas increased by 50'C per day for 14days. This is the polymorph that we synthesized.HP-GaS The sampletube was removed from the furnace a has a high-pressurestructure that can be derived few times a day and shakenin order to mix unreacted from the p structure. e-GaShas a lower symmetry, molten gallium and sulfur. Yellow homogeneous P6m2 (Goodman et al. 1985). Both HP-GaS GaS was obtained. The X-ray powder data for our and e-GaSare metastableforms of GaS, and their synthetic GaS are compared in Table I with those fields of stability are not known precisely.Ifthe heat- for synthetic GaS obtained by Hahn & Frank ing rate is too high during synthesisor the mixing (1955b).Goodman et al. (1985)proposed rhar rhere betweenliquid gallium and liquid sulfur is inefficient, are in fact three polymorphs of GaS: B-GaS,HP- a sugar-like,transparent white crystallinematerial GaSand e-GaS.Beta-GaS is a well-establishedpoly- that has excessgallium metal is produced. This morph that is stableat room temperatureand pres- material is GarSr, as determinedby X-ray powder sure; it crystallizesin the hexagonalspace-group diffraction and electron-microprobe analysis. P6r/mmg, and its unit-cell dimensionsare: a 3.585, Accordingto Hahn & Frank (1955a),GarS, also has c 15.50A lHatrn & Frank 1955b,Wyckoff 1963). threepolymorphs, named o, 0 and 7. Beta-Ga2S3is the disordered,high-temperature phase that has a wufizite structure, 7-Ga2S3is the disordered,low- phase TABLE 1. X-RAY PO{DER-DITFRACIIoNDATA FoF CaS temperature that has a sphaleritestructure, and o-Ga2S3is a superstructurephase with a wurtzite Hahn & Frank (1955b) This study. T0O1-1 structure. The fields of thermal stability of these d(a) r hkl doue(A) d.ar.(A) threephases are not well known. As shownin Table 7.75 st(-) 00? 7 .75 7 .73 2, X-ray data for our Ga2S,agree with those for ct- 3.875 si( - ) 004 3.8?0 3. S66 100 3. 105 st 100 3.100 3.101 GarS, obtained by Goodyear et al. (1961). 3.044 st 3.036 3.047 2.882 ss 1,O2 2.878 2.A7A I z.oor n 103 2.653 2.657 2 2.5B3 s 006 2.5?6 2.177 t7 2.423 s-h 104 2.419 2.4t9 1 SvNrHsrrc PHASE-EeurLrBRruMExpEnrMsNrs 2.194 e(+) 2.!A? 2.190 1.986 ss 106 1.9831 1.9820 I IN THE SYSTET4Zn-Fe-GA-S t .938 ssg 008 1.9333 1.9328 1.803 st(+) 707 1. ?989 I .7992 11 1.793 st 110 1.?89? 1.?905 7 Meteoritesthat. contain a Ga-bearingzinc sulfide 1.746 ss( -) tt2 7,7445 I.7443 1 .644 108 1. 6399 1 .6403 contain metallic iron and troilite and, therefore, have I.627 s-n L8247 1..8247 1.552 ss(- ) 200 1.5516 1.5506 formed at a low sulfur fugacity. Thus, many of our 1.550 00rQ 1.5465 1.5462 experimentsincorporated an FeS + Fe buffer. Five

hex. hex. assemblagesof starting materials were used: a 3.585 A a 3.5810(?)A (ZnS (ZnS c 15.50 A c 15.462(3) A A: + GaS) + 2(FeS+ Fe), B: + 2GaS) + 2(FeS * Fe), C: (ZnS + 4GaS) + 2(FeS + Fe), D: ZnS + GaS + FeS,and E: ZnS + 2GaS.Starting materials were mixed by grinding in an agate mor- TABLB 2. X-RAY POXDER-DITFRACTIOS DATA FOR a-GaaSs tar and were sealedin evacuatedsilica tubes.These Coodyea! ot al,. (1981) ThtE study, T026 wereheated in an electricfurnace at 900oCor 8fi)oC d(A) dore(!) da.r6(A) and were quenchedin cold water after heating for 5.33 tsa 110 5.34 20 13 to 4l days (900"C runs) or for 26 to 56 days 4,?7 ts 200 4.775 4. ?6S 1B (800oC 4.?3 n 1tl 4.732 4,724 7 runs). 3.515 w 3:.1 3. 518 Products were examined by reflected light 3.488 m 202 3.496 3.494 3.209 vE 020 3.21,5 3.Ztr ts4 microscopy and by X-ray powder diffractometry 3.010 a 402 3.014 r00 2,844 tu 310 2.444 2,A4A (Mn-filtered FeKo radiation), with Si as an internal 2.924 Ba Lt2 2.430 2,424 25 parameters 2,742 m 027 2,744 2.749 standard. Cell were calculated for some 2.654 i(b) 220 2.883 2.863 4 phasesby the least-squaresmethod from precisely ooz 2.65S 2,457 2.378 w 400 2,344 2.344 I measuredd-values. The phaseassemblages produced 2.353 vt 222 2,343 2.364 1 Z,2OB ts 511 2.205 2,209 are shownin Table 3. The chemicalcompositions of z.LSg r 203 2,197 phases 2. 185 w 2. 190 2.LSO the weredetermined with an ETEC electron ?.098 eF 2.toz microprobe using metallic iron, GaP, synthetic 2.085 @ 2 .089 2.0s0 2.O4O r 2,046 sphaleriteand synthetic troilite as standards.The 1.S03 w(b) 1.884 vt 1 .8868 analyticalresults, each an averageof severalgrains, 1.451 v6 2e L.424 r are shown in Table 4. All analytical errors are within 1.810 yw 0.1wt.9o. a 12.637A a L2.452<4>A b 6.41r A b 0.421.(3)a c ?.03e A c 7.044<2, A (Fe,Ga) alloy 9:131.0?(3)" b:latho! broad An alloy of Fe and Ga was obtained in runs T009, GALLIUM IN SPHALERITE AND WURTZITE 145

TABLE3. EXPERIIIENTALRESUITS FoR'rllE SYSTEI.I Zn-Fe-Ga-S AT 900'c AND800.C

Run no. TeEp.('Cl React,ants Bulk coBpositj.ons (At.?) Heati.ng Products Zn Fe ca S days

T009 900 Zng+oas r0.0 4ll.U 10.0 40.0 4I wz+porY +2(FeSaFe)

ro22 900 ZnS+ZCaS 8.3 33.3 16.? 41.7 20 sz+Y r2( FeS+Fe) T039 900 Zns+cas 16.7 16.7 16.7 50 . 0 13 !z+Y rI.eS

T033 900 ZnS+4CaS 6.2 Zb.O ?5.0 43.8 1.9 wztY 12( FeS+Fo)

TO27 900 ZDSa2CaS 16. 7 0 . 0 33. 3 50.0 22 sp+casaca

T010 800 ZnSrGaS 10.0 40 .0 10.0 40.0 56 iz+po+Y r2 ( FeSaFe )

T023 800 ZnS+2CaS 8.3 33. 3 1,6.7 4I .7 34 cz+\ t?( FeS+Fe) T040 B00 ZnS+GaS 16.7 16.7 16.? 5O.O 29 !z+Y iF eS

T034 800 ZnS+4CaS 6. 2 25 .0 25. 0 43.8 26 sp+Y r2(FeS+Fe)

t0?8 800 ZnS+zGaS 16.7 0.0 33.3 50.0 ZA sp+cas+Ca

rz:rulizrte. po:pyrrholit-e, Y:alloy (tr'e,Oa], sp:sphalerite

TABLE 4. CHEIIICAL COMFOSITION OF ALLOY Y, PYRRHOTITE AND SPHALERITE-UURTZITE

Run no. Teap.('c) ftoiElht z Atolic z Zn Fe Ga S !ota1 Zn Fe Ga S

alloy Y T00s 800 0 .o 73 'to22 .7 27.1 0. 0 100.8 0.o 77.3 22.7 0.0 900 0.0 6s.3 29.2 0.0 98.5 0.0 74.4 25.2 0.0 T039 900 0.0 69.2 31.6 0.0 100.8 0.o 73.2 26,a 0,0 T033 s00 0,o 67.7 32.7 0.0 99.8 0.0 72.0 28.0 0.0 T010 800 0.0 73.8 26. L 0.0 99.9 0.o 77.9 22.L 0.0 \o23 800 0.o 72.6 26.3 0.0 98.9 0.D 77.5 22.5 0.0 T040 800 0.0 89.4 28.1 0.0 97.5 0.0 75.5 24.5 0.0 T034 800 0 .0 70.3 31.0 0.0 101.3 0.0 73.9 26.1 0.0

Pyrrhot i.te T00s 900 0.0 63.? 0.0 36.6 100.3 0.0 50.0 0.0 50.0 T010 800 0 .0 63.2 0.0 99.8 0.0 49.8 0.0 50.2 sphaler i!e-iu rtz i te T009 sz 900 18.6 34.2 10.I 37.8 roL.5 12.7 27.4 7 .7 52.A TO22 cz 900 l6.L 23.2 23.I 37,O 9S.4 L1.5 19.3 15.4 T039 wz 900 25.O 16.1 22.0 37.O 100.1 17.9 13.5 t4.7 T033 rz 900 11.4 17.5 32.0 38.3 93.1 4.2 L4,8 21,.4 T02? sp 900 2r .6 0.0 36.6 101.1 20.1 0,O 24.9 T010 rz 800 2f.O 34.2 6. S 98.5 14.I 28.2 4.5 52.5 TD23 cz 80u 15.6 22.6 23.5 37.A s9.5 11.1 18.? 15.6 54.6 T040 rz 800 25.4 15.3 21 . I 99.5 18.2 L2.9 14.A T034 sp 800 10.9 A.A 40 ,2 38.6 98.5 7.9 7.5 27.4 T028 sp 800 40. 3 0.0 23.8 100.4 29.5 0.0 16.3 54.2

T022, T039 and T033 at 900oC and T010, T023, TABLE 5, X-RAY POI{DXR-DIF!'RACTIONDATA roi a-IRoN AID ALTOY Y T040 and T034 at 8&)oC. The alloy is yellov/ishwhite 1. a-iro! 2. allov, Fe"ocalo 3. allov' Pe7a.egaz?.L in reflectedlight and showsno anisotropism. It is d(A) I hhl d(A) I hk1 dob.(A) d'.ro(A) I hLl 3. ?000 c 100 optically similar to iron, but has a distinctly differ- 2.AAO3 t 11o 2.1210 ws 111 2.MA 2.I44 100 112 ent X-ray-diffraction pattern. Table 5 showsthe X- 2.0268 100 110 2,054 2.058 00 103 1.8384 vs 200 1.85S4 1.8602 96 200 ray data of o-iron, an alloy of composition I.6457 w 210 1.5080 vvr 211 Fer6Ga36(Dasarathy t964), and our alloy L.4332 20 200 1.3010 e 22O 1,3153 1.3154 A5 22O Fg7.eGa72.1(run T0l0). Alpha-iron has a body- L.22gO w, 22t 1.2354 1.23A4 ?4 222 centeredcubic cell, whereasalloy Fe76Ga3ohas a 1.1702 30 ?11 1. 1eB4 vve 310 t6t!agonal primitive cubic cell (Dasarathy 1964). The five a 2.8864 A a 3,6834 A a 3.?20(1) A, c 7.40(1) A diffraction lines observedfor our alloy (Fg7.eGa22.1) 1: PDF 6-08€0 2: Dasalathv (190a) 3: this atudv, T010-000'C r46 THE CANADIAN MINERALOGIST

TABLE 6. X-RAY POI{DER.DlFFRACTIONDATA FOR SPHALERITE 4. At 900oC,gallium contentsof alloy Y vary from PDF 5-566 22.7to 28.0 atomic 90, and at 800'C f.rom22.l to

Ga sontent 16.3 at.? 24.9 aL.Z 27.4 at.Z 26.1 atomic 90. Thesecompositional variations are with gallium d(A) I d(A) I d(A) consistent the contentsof the bulk com- positions of the reactants.We did not obtain the 3. 123 100 111 3.070 100 3.044 100 3.037 100 2.705 I {i 200 2.656 2 2.641 4 2.627 1 FeroGa36phase reported by Dasarathy (196a). L.9t2 51 220 1 . B7B5 43 1.8648 40 1 .8570 44 a 5.4060 A 5.313(1) L 5.27A(2)A 5.253(Zt A Sulfides

Plrrhotite was obtained in runs T@9 at 900oCand T0l0 at 800"C (Table3). It containsneither Znnor TAB'.8 ?. X-RAY PO|DEN-DIFT,RACTIOIDATA rON TURTZITA Ga and is nearly stoichiometricFeS (troilite) (Table PDr 5-4S2 4). Ga-bearingsphalerite, Ga-bearing wurtzite, or Ca oontoni 7.! dt.Z 15.4 at.Z !4.7 at.Z 2!.4 6t.t their mixture wereobtained from all runs (Table3). d(a) r b|l d(!) r d(a) r d(!) r d(!) r Microscopically, both Ga-bearingsphalerite and Ga- 3.30e 100 100 3.300 100 3.2?3 100 3.27!- tOA 3.255 8o 3. L2e 86 002 3,115 77 3.O9? 03 3.08? ?5 3.OOB 100 bearingwurtzite are grey with bluish tint, have no 2.523 a4 101 2.S1€ 68 2.981 60 2.68S 92 2.A73 68 2.2?3 2S LO2 2.2A7 33 2.245 4D 2.24A 4D 2.232 92 anisotropism,and are very similar in appearanceto 74 110 1.S085 62 1.8801 68 1.8085 ?S L.A777 A2 1.764 62 103 1,?592 58 1.7433 e3 L.?433 ?I L.7327 07 Ga-free sphaleriteor Ga-free wurtzite. Thesetwo a 3.820 3 3.810(1) A 3.?80(r) ! 3.7?8(1) A 9.?56(t) e mineralscould be distinguishedonly by X-ray pow- c 9.280 ! 6.233<2) A A.177(2) t 6,1?8(2) ! 8.140(2) ! der diffraction (Tables6, 7). Resultsof microprobe analysesare listed in Table 4.

can be indexed usjng a tetragonal cell having a 3.720(l),c7.40(l) A (Table5). We havenamed this DIscussloN alloy "phase Y". Compositionsare listed in Table Variotions of cell parameters of sphalerite and wurtzite

Barton & Toulmin (1966)determined the depen- denceof the unit-cell parametera of sphaleriteon sphalerite its Fe content o = 5.4093 + 0.0005637X- 0.000004107*, where X is mole 9o FeS in solid solution^.The maximum value of a they obtainedis 5.4280A for sphaleritecontaining 56 mole 9o Fe$. The maximum increasein a thus is only 0.0187A. In contrast, the effects of Ga on the unit-cell parametersof sphalerite and wurtzite are very large (Tables6 and 7, respectively).Figure I is a plot of the unit-cell parametera of Ga-bearingsphalerite versaschemical composition, given as the atomic ralio Ga/(Zn+Fe+Ga). Figure2 is a similar plot for Ga-bearingwurtzite. The unit-cell parametersof sphalerite and wurtzite decreasedramatically with increasinggallium content. On the other hand, an increase in the iron content increasesthe cell parameters of both phases. Therefore, for Ga-

1027 bearingzinc sulfidecontaining much iron (e.g.,TM9 (Ga 24.9, Fe 0.0) with2J,4 atomic 9o Fe), the valuesof a and c devi ate from the straight lines in Figures I and 2. The differencein a betweenGa-free sphalerite and Ga- ,lGa 27.4. F6 7,51 rich Q7.4 atomic 9o Ga) sphaleriteT03f at the same 0 0.1 0.2 0,3 0.4 0.5 0.6 0.7 Fe contentof 7.5 atomic 9o is 0.164A, almostan Ga/(Zn+Fs+Ga) order of magnitude larger (and in the opposite direc- Fig. 1 Relationshipbetween unit-cell parametera of Ga- tion) than the entire rangethat resultsfrom Fe sub- bearing sphalerite and composition, expressedas stitution (Barton & Toulmin 1966).The differences Ga/(Zn+Fe+Ga) ratio. The range in a of Ga-free in a and cbetweenpure wurtzile and Fe-begring,Ga- sphaleriteis from Barton & Toulmin (1966).Numbers rich wurtzite T033 are 0.064 A and 0.12 A, respec- in bracketsexpress the atomic 9o of Ga and Fe. tively. GALLIUM IN SPHALERITE AND WURTZITE 147

Hahn et al. (1955)measured the variationsof cell a (A) parametersof phasesalong the Ga2S3-ZnSbinary 3.84 join at 900'C. About 20 mole 9o ZnS can be accom- modatedin solid solution in Ga2S3.The solid solution has the sphaleritestructure, and a increasesrvith 3.A2 increasing ZnS content. More than 30 mole Vo

GarS, can be incorporatedin ZnS. This solid solu- 3.80 tion hasthe wurtzite structure,and a and c decrease with increasing Ga2S3content. Hahn et al. svg- 3.78 gestedthat a tetragonal ZtGa2Saphase oceupies the (Ga 15.4, Fe 19.3) T039 middle rangealong this binary join. Dissolution of (Ga 14.7,Fe 13.5) produces 30 mole 9o Ga2S3in ZnS the composition 3.76 Zn2a.1Ga2s.7S5r.r.In our investigationof the GaS- ZnS binary join, Ga-bearingsphalerite was obtained over the compositionalrange from Zn26.rGas.eS55.o3.74 0.5 0.6 at 900'C to Zn2e.5Gat63Sr4.2at 800oC, with no indi- Ga/(Zn+F€+Ga) cation of a tetragonal ZnGa2Saphase. The dramatic decreasein cell volume of Ga- c (A) bearing zinc sulfide with increasingGa content is 6.28 E explainedby considerationsof ionic sizeand va.lence. wurtzite The ignic radii of Zn2+ and Ga3+ are 0.74 A and 0.62 A, respectively.Furthermore, in order for Ga to enter into the sphaleriteor wurtzite solid solution, vacancies must be created to maintain charge 6.24 balance.The probablesolid-solution model is writ- i Tooe ten (Zn,Fe,Ga, n)S, whereI representsa vacancy, (Ga 7.'1,Fe 27.4, or (Zn,Fe,Ga)r-rS. 6.22

Stobility relations betweenwurtzite ond sphabrttu in 6.20 the system Zn-Fe-Ga-S

6.18 TO22 Scott & Barnes (1972) determineda univariant T039 \ (Ga 15.4,Fe 19.3) sphalerite-wurtziteboundary as a function of sul- (Ga 14.7.Fe 13.5) fur fugacity and temperatureat I bar. They proposed lhat in the pure Zn-S system,sphalerite is stableat relatively high sulfur fugacity, and wurtzite is stable at low sulfur fugacity. The effect of solid solu- (Ga 21.4, Fo 14.6) tions on this relationship is not well known, although substitution of Fe for Zn increasesthe sulfur fugacity over which sphaleriteis stable(Barton & Toul- 0 0.1 0.2 0.3 0.4 0.5 0.6 min 1966,Hutchison & Scott 1981).As shownin Ga/(zn+Fe+Ga) Table 3, most runs in the presentexperiments were Fig. 2. Relationshipbetween unit-cell parameters of Ga- performed by using FeS+Fe as reactantsand thus bearing wurtzite and composition,expressed as should havebeen buffered at or nearthe low sulfur Ga/(Za+Fe+Ca) ratio. A) Data for a,' B) data for c. fugacity defined by the pair iron + troilite. However, Valuesof a andc of Ga-freewurtzite are from PDF 5-4492. iron was totally consumedin many of theseexperi- Numbersin bracketsexpress the atomic 9o of Gaand Fe. ments.Runs T009 at 900"C and T0l0 at 800'C were buffered by pyrrhotite + alloy Y and produced wurtzite, in agreementwith the stability relationsof Solubility of gallium in sphalerite and wurtzite Scott & Barnes(1972). The products of runs T022, T039,and T033at 900oCand of runsT023 and TMO Runs T027 at 9moc and T028 at 800oC,with reac- at 86oC are wurtzite + alloy Y, which indicatesthat tants ZnS + 2GaS, producedthe univariant assem- they, too, were carried out at low sulfur fugacity. blage sphalerite + GaS + Ga. Therefore, 24.9 Run T027 at 900oC and runs T034 and T028 at atomic 9o Ga for T027 and 16.3 atomic 9o Ga for 800oCproduced sphalerite,indicative of high sul- T028 are the maximum solubilities of Ga in sphalerite fur fugacity. Our data are not yet sufficiently numer- in the ternary systemZn-Ga-S at 900oCand 800oC, ous to provide unequivocalphase diagrams for the respectively. Univariant assemblageswere not svstemGa-Fe-Zn-S. obtained in the system Zn-Fe-Ga-S, so that the 148 THE CANADIAN MINERALOGIST maximum solubility of Ga in zinc sulfide is not Aluminiums,Galliums und Indiumsmit Zink, Cad- known for the quaternary system.The maximum Ga mium und Quecksilber.Z. Anorg. Allgem. Chem. contents measured were 2L.4 atomic 9o Ga for n9.241-270. wunzite at 900'C (run T033), 15.6atomic 9o Ga for wurtzite at 800oC(run T023), and 27.4 atomic q0 HurcrrsoN,M.N. & Scorr, S.D. (1981):Sphalerite geobarometry Ga for sphaleriteat 800oC(run T034).These values in the Cu-Fe-Zn-S system,Econ. Geol.76. 143-153. are considerablylarger than thosereported for Ga- bearingzinc sulfidesin meteorites(Nagahara & El JoHeN,2., OunrN,E. & Prcor,P. (1983):Analogues Goresy 1984,Woolum et al. 1984,Rambaldi e/ o/. germanifbreset gallifdresdes silicates et oxydesdans 1986),which indicates,not unexpectedly,that the lesgisements de zinc desPyr6n6es centrales, France; zinc sulfide in thesemeteorites is not saturatedwith argutiteet carboirite,deux nouvelles espices min€- Ga and thereforecan provide no P-T information. rales.Tschermaks Mineral. Petrcq. Mit t. 31, n -n9.

AcrNowLsncEMENTS KLEuv, W. & Vocrl, H.U. (1934):Messungen an Gallium- und Indium-Verbindungen.X. Uber die Chalkogenidevon Gallium Indium. Z. We thank Claudio Cermignani of und Anorg. University of Allgem. Chem.279, 45-64. Toronto for technical support and Toshio Mizuta of Akita University and Yoshihiro Nakamuta of Lrrru, R.M.A., Heulrcens, H.J.M. & HrrrorN, Kyushu University for their valuable suggestions. C.W.M.V.D.(1966): The P-T-X phasediagram of The manuscript was substantially improved through the systemGa-S. "/. Electrochem.Soc. 113, 798-801. the critical reviewsof R.F. Martin and two anony- mous referees.This researchwas supportedby the -, -& (1967):The vapour pressure Ministry of Education of Japangrant to Ueno, which and thermal stability of gallium sulfide. Mater. Sci. enabledhim to spend a year at the University of Eng. 2, 193-200. Toronto and by NSERC Operatinggrant A7069 to Naceuane, H. & Er Gonrsy, A. (1984):Yamato- Scott. 74370;a new enstatitechondrite @H4). Lunor RSFERENcES Planet. Sci. 15. 583-584.

BaRroN,P.B., Jn. & TouLvrN,P., III (1966):phase RananALDt,E.R., Ra;eN, R.S., Housrrv, R.M. & relationsinvolving sphaleritein the Fe-Zn-S system. Warc, D. (1986):Gallium-bearing sphalerite in a Econ. Geol.61. 815-849. metal-sulfidenodule of the Qingzhen@H3) chondrite. Meteoritics2\, 22-31. BERNsrerN,L.R. (1986):Geology and mineralogyof the Apex germanium-galliummine, Washington Rusrevov,P.G. & ManDaxHAEv,B.N. (1964):About County, Utah. U.S. Geol. Sun., BulL IS77, the syntheticmethods of alloysand compoundsin the sulfur-bearingsystem. Dokl. Akad. Nquk Azer- Dasenaruv,C. (1964):Order-disorder change in Fe- baidzhanskoiSSR 20(9), l3-15 (in Russ.). Ga alloys.J. Iron SteelInst. (London) 20Z, Sl. Scorr, S.D. & Benxrs, H.L, (1972): Sphalerite- GooDMAN,P., OlsrN, A. & Wsrrrrelo,H.J. (1985): wurtzite equilibria and stoichiometry.Geochim. An investigationof a metastableform of GaSby Cosmochim.Acta 36, 1275-1295. convergent-beamelectron diffraction and high- resolutionelectron microscopy. Acta Crystallogr. SHrra,I.A., Cueus,I.S. & Mrryursve,T.T. (1966): B,4t,292-298. The Chemistryof Gallium. Elsevier,Amsterdam.

Goooyrat, J., Durrrx, W.J, & SrucuaNN, G.A. WooLuu,D.S., Bnooxs,R., Jovcn,D., Er GonEsv, (1961):The unit cell of a-Ga2S3.Acta Crystallogr. A., Berraun, T.M., Rocrns,P.S.Z., Maccronr, 14.ll68-1170. C.M. & Drmv, C.J. (1984):Trace element PIXE studiesof Qingzhen@H3) metaland sulfidq. Lunor HeHr, H. & Fnarr<,G. (1955a):Zur Struktur des Planet.Sci. 15, 935-936. Ga2S3.Z. Anorg. Allgem.Chem. 278,333-339. Wvcrorr, R.W.G. (1963):Crystal Structures 1 Qnd. +, (1955b):Uber die Kristallstruktur des ed.). Interscience,New York. GaS.Z. Anorg. Allgem.Chem.278,340-348.

Krrxcrrn, W., Sroncen,A.-D. & ReceivedApil 30, 1990, revisedmanuscript accepted Srdncrn,G. (1955):Uber terniireChalkogenide des Septemberll, 1990.