American Mineralogist, Volume61, pages260-265, 1976

57Fe Miissbauereffect study of and lreSnin stannite, stannoidite,and mawsonite

Tnrlurrsu YnvnNnrn Mineralogical Institute, Faculty of Science Uniuersityof Tokyo, Il3 Hongo, Tokyo, Japan

nNp Arrne Ke.ro Departmentof Geology,National ScienceMuseum Tokyo, Japan

Abstract

The valencyformulae of mineralsin the systemCu-Fe-Sn-S were determined with the aid of electronprobe microanalysisand of the Mdssbauereffect study of s?Feand rleSnat temperaturesof 80"K and 293'K. The formulaeof stannite,stannoidite, and mawsonite can be expressedas Cu!+(Fe2+,Zn"*) Sno*S?-,Cul+Fe!+(Fe,*, Znt*1Sn!+S!r-, and Cul+FeB+ Sno+S3-respectively. Zn wasfound to substituteonly for thefeirous ion. Mawsonitecontains no zlnc. The quadrupolesplittings and isomershifts could be rationalizedwith crystalfield effects causedby thedifferences in sitesymmetry around the Fe andSn atoms. Quadrupole splittings and isomershifts o[ ""Sn indicatethat the (SnSo)-tetrahedronof these specimens is strongly covanentlybonded, and that it may be regardedas a chemicalradical bearingspt hybrid orbitals.Site symmetries around tin atomsin thesestructures are similar. The most probablespace group of mawsoniteis I42m, l4mm, 1422,or 14,22,based on its X-raypowder diffraction pattern and the site symmetries of tin andiron ionsdetermined from the Miissbauereffect study.

Introduction The crystal structure of stannite analyzed by Mawsonite, stannoidite, stannite, and rhodostan- Brockway ( 1934)is closelyanalogous to that of chal- nite are mineralsin the systemCu-Fe-Sn-S. Some of copyrite. Further, the crystal structureof stannoidite their crystalstructures are saidto be similar to that of has recently been analyzedby Kudoh and Tak6uchi chalcopyrite.Markham and Lawrence (1965) stated (1974\.This structure indeed resemblesthat of chal- that mawsonite was pseudocubic,with the chemical copyrite, but is more delormed comparedto stannite formula CurFerSnS,o.Kato and Fujiki (1969) de- because of the presence of additional interstitial scribed stannoidite as orthorhombic with chemical cations. Stannoidite has four copper sites,two iron composition CuuFerSnSr. Boorman and Abbott sites,and one tin site. The structuresof other minerals (1967),Springer (1968), and Petruk (1973)reexam- in the above-mentionedsystem are still not defined. ined the chemical compositions of these specimens The cation valencesof theseminerals are still am- and defined stannoidite as Cur(Zn,Fe)rSnrS, and biguous, becausechemical analyseshave not been mawsonite as Cu.FerSnS.. conducted in considerationof the valency statesof Springer(1972) showed in his work on phaseequi- cations. Since iron, copper, and tin may all have librium diagram for CurFeSnSn-CurZnSnSothat at a severalvalencies in crystallinephases, complications temperatureabove 680oC syntheticstannite forms a arise in defining the valenciesof thesecations. solid solution with synthetic kesteritein the whole Pauling and Brockway (1932) and Hall and Stew- range of zinc-iron substitution; that the former has art ( 1973)discussed the valencyformula of chalcopy- polymorphic structuresof a-phase and B-phase;and rite from the bond lengthsdetermined by X-ray crys- that the increasedZn substitution in stannite will tal analysis,and they reported that chalcopyriteis a reducethe temperatureof transition betweenthe two mixture of two statesCu'+Fe3+S3- and Cu2+Fe2+S!-. phases. But the neutron diffraction study by Donnay et al. 260 ,L9SN 261 MOSSBAUER EFFECT STUDY OF 57FCAND IN STANNITE

of specimens (1958) and Mdssbauer effect study by Chandra and TlsLe 2. Cell dimension Puri ( 1968)show that the iron ion in chalcopyritehas Stannite Stannoidite l"lawsonite a singletrivalent state. The M6ssbauer effect can determine the charge 5.461+0.002 a= 10.789 + 0.009 a=70.?45+0.00I valenciesof iron ions. The cation valenceof Fe in 5.413 + 0.004 + c=10.711+0.006 stannitehas beendetermined by severalinvestigators 10.726+0.007 c= I6.155 0.009 (1967), Eibschutz et al. Marfunin and Mkrtchyan S,G. S.G. PTeswable S.G. (1968). (1967),and Greenwoodand Whitfield 742n(7) rzzzQ) r42n, r+*(3) The presentstudy eliminatesthe ambiguity about 1422, 14r22 the valencyformulae of stannoiditeand mawsoniteas (1) Brocl<'tay (1934) well as stannitewith the aid of the Miissbauerspectra (2) ktdoh ml lakeuchi (1.974) of both u'Fe and 1leSn.It also discussesthe site sym- (3) Present assmrptLon metriesof iron and tin and of the characterof Fe-S and Sn-S bonds in theseminerals in comparisonwith synthetic samples and some other sulfidessuch as 1970), stannoidite (Petruk, 1973) and mawsonite chalcopyriteand sphalerite. (Petruk, 1973;Kulichikhina and Vyal'sov,1969). Cell dimensionsof stannite,stannoidite, and maw- were obtained by X-ray powder diffractometry Material and experimentalmethod sonite and were calculated with the aid of least-squares Stannite from Gyojayama, Kyoto Prefecture,and method using UNICS computer program. The cell stannoiditeand mawsonitefrom the Akenobe mine, dimensionsof the samplesare presentedin Table 2. Hyogo Prefecture,were separatedfrom the ores un- Mawsonite was reportedto be pseudocubicby Mark- der the ore microscopeand by the subsequentcrush- ham and Lawrence(1965), Levy (1967),and Kuli- ing, magnetic, and specificgravity separations.The chikhina and Vyal'sov (1969)' Better indexing of the occurrenceand paragenesisof these minerals were mawsonitepattern usingthe computer program writ- reported by Lee et al. (1974). Synthetic CuzFeSnSa ten by Evans et al. (1963) implied tetragonal symme- and CurFeaSn2Sl2were preparedin an evacuatedsil- try as shown in Table 3. u'Fe r'eSn ica tube and identifiedby the ore microscopicand X- Mdssbauerspectra of and in the natural ray powder diffraction methods.Their homogeneities and syntheticmaterials were obtained at 80'K and at wereconfirmed by electronmicroprobe. Chalcopyrite room temperature (293"K) by using a HITACHI/ u'Co from the Arakawa mine, Akita Prefecture,and cuba- RAH/-403, 400 channel analyser. diffused in llemsn nite from the Kohmori mine, Kyoto Prefecture,were metallic copper (10 millicuries) and doped in employed for reference.Some of the natural samples BaSnOs(2 millicuries) were used as sources.These were analyzed by the electron microprobe method, y-ray sources have fairly large recoilless fractions using a computer program modified on the basisof and give absorption peaks with very narrow-line the correction formula devised by Sweetman and widths. The line widths of the inner two lines of the the Long (1969), as shown in Table l. Their recalcula- spectrum of "Fe in metallic iron and those of tions gave an empirical formula for each specimen. spectrumof treSnin SnOzmeasured at room tempera- These were in good agreementwith the previously ture were 0.30 mm/sec and 0.83 mm/sec, respec- reported formula of stannite (Ramdohr, 1960;Oen, tively, with these sources. Spectra were taken by the mechanismof moving Teslr I . Chemical analysisof specimensin the system the source at both temperatures.Measurement at Cu-Fe-Sn-S 80oK was conductedwith both source and absorber in a cryostat. Stannite Stannoidite Mailsonite The intensity of the 14.4 keV emitted from wtt rclt ut? mol% wt% nol? 7-ray u'Co and the 23.8 keV from were de- Cu 30.11 24.77 38.49 31.69 44.15 35.48 7-ray "'*Sn t3 44 12.58 10.04 9 4r 12.95 11.84 tected by a Nal scintillation counter. The spectraof Zn 1.07 0.86 3,62 2 90 0.00 0 00 '?Fe obtained at constantDoppler velocitycalibrated 8.33 14.58 6.27 Sn 28 55 t2 59 18.89 in metallic iron were analyzedwith the aid of 30.l8 49.21 29.21 47 -67 29,14 46.41 by those program which performed least mean t03.35 100.00 100 26 100.00 100.82 100 00 a computer fits of the experimentaldata to the Lorent- htrpirical squares Cu2(Fe, Zn)SnS4 Cu^(Fe, zn) ^ Cu6Fe2SnSS Fomula "Sn^s, zian function. This calculation did not employ a T. YAMANAKA AND A. KATO

Tnalr 3. X-ray powder pattern of mawsonites from Mt. Lyell, d-electrondensity in iron ion. The orbits of p- and d- Tasmania,and the Akenobe Mine, Hyogo prefecture,Japan electrons play the role of screeningthe s-electron from the positive electric charge of the nuclei. Fd+ t. 2. (3d), which has one more 3d-electronthan Fe8+ d(A) d. (At' d rA) I. hkl obs' carc' ' oDs (3d), shows a larger screeningeffect and a decreased 7.62 7.60 3 110 electrondensity around the iron nuclei,which causes 5.37 20 5.38 5.37 l0 200 the (Walker 4.37 20 4.38 4.38 t5 7 7 2 larger isomer shift for Fe'+, et al., 1962; 3.80 r0 3.80 3.80 I 220 Simaneket al.,1968; Watson, 1960a,1960b). 3.34 l0 3.378 5.388 4 103 3.09 r00 3.099 3.099 I00 222 Covalency of Fe-anion bonds also influencesthe 2.87s 20 2.868 2.869 10 312 isomer shift. Increasein the ionic character of the 2.680 50 2.684 2.686 2s 400 2.462 2.46I 3 114 bonds causesa decreasein the density of s-electrons 2.395 l0 2.401 2.40r 8 402 around iron nuclei and raisesthe isomer shift in both 2.287 l0 2.29L 2.289 J JJZ 2.I85 5 2.792 2.L92 3 422 ferric and ferrous ions. 2.098 s The quadrupole splitting u?Fe r. 959 5 r.962 r.962 3 s2r of dependson the l. 895 80 r.899 1.900 440 electric field gradient at the iron nuclei, which is l. 788 s 1. 791 t.790 3 442 L.739 5 7.742 7.742 3 523 induced from the valency electrons and from the r .618 80 1.620 L.620 40 622 surroundinganions. The electricfield gradient is also L.s47 10 1.549 I .549 7 444 1.460 5 L.463 1.462 3 72r attributed to distortion of electron orbits due to the r. 366 r. 565 3 651 crystal field and the covalent bonding character,(ln- r.343 20 1.344 L.343 15 800 1.318 1.319 3 tl8 galls, 1962, 1964;Sternheimer, 1963). The electron A 1.302 7.302 644 cloud of Fe2+is more likely to be distorted and more '. ZJZ JU 1.233 1.232 l0 662 1 )it q r.20t 1.201 5b 804 sensitiveto the configuration of surrounding anions 1.096 l. 096 l5 844 than that of Fes+and consequentlyexpected to give a a = 10.74A a =10.745J0.0013 larger value of quadrupole splitting, while Fe3+pre- c = 10.74A c =10.711r0.0063 sentsa sphericallysymmetric electron cloud. It must, however, be noted that in the casewhere the Fe2+site 7. Ibuteonitu. Mt.LyeLL, lasnania, After l,Aukhan and tantence (1965). Co radia.tion. Cmera nethod. symmetry is as high as cubic, Fe2+compounds would

2. I4ausonite. Akercbe nLne, Hyogo p?efecture,-(b Japan, Cu/Ni show no or very small quadrupole splitting. The in- ndiabion. Diffractoneter = mellod. br-oadf. fluenceon the quadrupolesplitting of the deviationof the symmetry of ligands from the cubic symmetry (43m) in sphaleritestructure to the monoclinic (2) in Gaussiancomponent causing a deviation of line pro- stannoidite could be recognized in this study as file from the Lorentzian curve,although the true line shown in Table4. shapemay be closelyapproximated by a combination of Gaussianand Lorentzian functions. t'"Sn Mbssbauer spectra The minimized variableswere (l) peak position, (2) full width at half-maxirnum intensity, (3) peak Neutral tin has the electron configuration intensity, and (4) off-resonancebackground count. [Kr](4d10)(5s')(5p").Sna+ has the electronconfigura- Various numbers of peaks assumed to be present tion [Kr](4d'o); Sn'* has [Kr](4/oX5s'). Since tet- were tested for the best fit. ravalent tin is little affectedby contributions of the lreSn ln the analysis of the spectra,a Pd-filter (70 p (5s) electron,the isomer shift of Sno+in rleSnM6ss- thick) having a K-absorption edge of 24.3 keV was bauer spectrais very small. On the other hand, diva- applied to eliminate the K-X-rays with energiesof lent tin ion exhibits a very pronounced isomer shift 25.04,25.27and 28.49 keV. due to a large contribution of the (5s') electrons. 5?Fe lleSn Isomer shifts of and spectra of each Increaseofcovalent characterofSn2+ resultsin the sample were measuredwith referenceto the isomer formation of (5s'z)(5p')or other s-p hybrids thereby shift of 310 stainlesssteel and SnOr, respectively. slightly reducing the isomer shift. Many covalent- bonded tin compounds consist of tetrahedral four- Experimental resultsand discussion fold structures bearing (sp3)hybrid orbitals, as do carbon compounds. In some cases,the (5d) orbital It has been proved that the isomer shift increases takes part resulting in the formation of trigonal dipy- with decreasesin s-electrondensity and increasesin ramidal five-fold coordination as the (spad) hybrid MOSSBAUER EFFECT STUDY OF UTFCAND I,gSNIN STANNITE

Tlst-r 4. Mdssbauerspectra of6?Fe at 293'K and 80oK

293'K 80'K s. Specinen Q. Val ency

I{awsonite 0.53 0.03 0.L7 0.03 0.56+ 0.03 0.28+ 0.03 Fe"' Unknom Stamoidite (i ) 0.53 0.03 0.54 0.03 0.56t 0.03 0.39t 0.03 Fe- 2 )+ (II) 0.76 0.06 2.86 0.06 0.87+ 0.08 3.08 + 0.08 Fe- 222 -3+ Synthetic Stamoidite (r) 0.50 0.03 0.36 0.03 tse 2 1L (II) 0.76 0.08 2.86 0.08 tse 222 Stannite 0.78 0.03 2.80 0.03 0.84+ 0.03 3.02i 0.03 Fe- 42n ?+ Synthetic Stmnite 0.76 0.03 2.86 0.03 Fe- 42n chalcopyrite 0.34 0.03 0.00 0.0c 0.50 + 0.03 0.00+ 0.03 Fe' Cubanite 0.50 0.03 0.88 0.03 0.53+ 0.03 1.01+ 0.03 Fe- 222 57r" Spharerite ir (zr,,ru)s 0.67 0.06 0.8r 0.06 0,89+ 0.06 2.02+ 0.06 Fe- 43n

57Ee Doppler oeLocity is calibrated by t\e spectrm of Ln netallic i.on. s7_ taome" gnLJt 1r.5.) and qmdrupole spLttting (Q.5. ) tre ?e Latlte xo f e in 3L0 stainless eteel. orbit or an octahedral six-fold coordination as the gradient around the tin ion. The minerals are each (sp'fr) hybrid. Within the samestructural configura- confirmed to have only one strongly covalently tion, the isomer shift of compounds containing bonded four-fold coordinatedSna+ ion. The fact that {SnXol and [SnXu] groups decreaseswith the elec- the isomer shift and quadrupole splitting of "eSn is tronegativityofthe surroundinganions (Stdckler and nearly identical in all three mineralssuggests that the Sano,1968). tin coordination is very similar although the sitesym- The isomer shifts of "'Sn in stannite,stannoidite, metry of the ion may be different. and mawsoniterange from 1.45+ 0.03 to 1.48+ 0.03 In spiteof the anomalouslylong Fe-S bond lengths mm/sec (Table 5). Thesevalues support the assump- in the system (for example, 236 A in stannite) and u?Fe tion that the SnSo-tetrahedronof these minerals is the high site symmetry, Mdssbauer spectra of strongly covalent and may be regardedas a chemical stannite and stannoidite show a much larger quad- radical such as are found in sulphosalts. rupole splitting than that of other sulfidescontaining The quadrupolesplitting of lreSnis not an effective iron atoms.This may be explainedby the fact that an means for determining the electric chargeof the tin iron atom bridges two (SnSr) tetrahedra which are ion. lt has been proved that Mdssbauer spectraof stronglycovalently bonded groups, and that the Fe-S ionic Sn'+ compounds have a tendency to show a bonds may also have largely covalentcharacter. greaterquadrupole splitting than those of Sna+com- gener- pounds. This is becausethe latter compounds 57Fe Mbssbauer speclra ally consist of highly symmetric coordinations around the tin ions. Furthermore,the higher the co- Slannite. The isomer-shiftsof natural and syn- valency of the Sn-X bonds, the lessthe interaction thetic stanniteprove the iron to be divalent(3r1"). The betweenthe quadrupole splitting and electriccharge small values compared with isomer shifts in many of tin ion. other ferrous compounds confirm the existenceof A seeminglysingle broad peak was observedin the lreSn spectraof stannite,stannoidite, and mawsonite. TesLe5. M6ssbauerspectra of""Sn Little or no quadrupole splitting was detectedeven r.s. Q.s Si ra after computer processingthe data. Somequadrupole Specinen Valencv - (nn/sec) (m/scc) symetry splitting may be assumedto be presentat leastin the l',la{sonite L46 + 0. 05 0.00 00s (snS,)- unknoM - spectraof stannoiditefrom the fact that the sitesym- Stanoidite 1.48 + 005 0.00 0.05 (SnS, ) 2 - )-- metry around the four-fold coordinated tin atom is Stanni te 1.45 + 005 0.00 005 (SnS,) 42n Synthetic Sns 3.48 + 0. 03 0. 9l 005 Sn'- n (222), which deviates considerably from (42m) of ^4+ Cassiteti te 000+ 0.03 0.40 0.05 mn The absence of observable quadrupole stannite. . lls (Q,S ore splitting probably results becausethe [SnSr] group Is@e" ehift (1.5.) and qwdtupole spLitLing ) in the svilthetic SnOz does not have a sufficiently large electric field 264 T. YAMANAKA AND A. KATO

highlycovalent bonds. In spiteof the42msymmetry and isomershift are aboutthe sameas thoseof the of iron ions in stannite,the exceedinglylarge quad- inner doublet(1) in the spectraof stannoidite,in- rupole splitting also indicatesthe presenceof the dicatingthe existenceof ferric ion in an analogous covalentbonds. This may bebecause iron sharesone coordination. of sulfur ions of (SnSn)n-group havingthe afore- Thoughthe crystalstructure of mawsonitehas not mentioned(sps) hybrid bonds. beenanalyzed because of difficultiesin obtaininga Syntheticstannite having no zinccontent shows a singlecrystal, the presentX-ray powderdiffraction higher absorptionpeak, a slightlysmaller isomer- dataand the Mdssbauerspectrum have considerably shift and a little larger quadrupolesplitting than clarified the structure.The most probable space thoseparameters for natural stannitehaving 9 mole group is 142m,I4mm, 1422or 14122to be consistent percentof zinc.It may be concludedthat zinc sub- with site symmetriesaround the tin and iron ions stitutesfor ferrousion and increasesthe ionicity of its determinedfrom the Mcissbauereffect study as well bonding. asof the indicesof powderdiffraction peaks. Stannoidite. There existtwo pairs of doubletsin the Mbssbauerspectra of naturaland synthetic stan- Acknowledgments noidite.Isomer shift and quadrupolesplitting of the innerand outerdoublets prove the existenceof both The authors are very indebted to Professor R. Sadanaga,Profes- ferrousand ferric ions in stannoidite.The observed sor Y. Tak6uchi,and Dr. Y. Kudoh, MineralogicalInstitute, Uni- absorptionintensity (2.38Vo) of the innerdoublet of versity of Tokyo, for their fruitful discussion and comments, and wish to thank Dr. M. S. Lee, zinc-freesynthetic Departmentof Mineral Development stannoiditeis almost twice as Engineering, University of Tokyo, for his guidance in synthesizing muchas that of the outerone (l.2lEo). Since it canbe the samples. reliablyassumed that each recoilless fraction and sat- urationeffect is not very differentat the two iron sites References of stannoiditebecause of the sameeffective width of the absorberand identicalsite symmetries, the ratio BoonunN,R. S., eNo D. ABBorr (1967)Indium in co-existing of absorptionintensities mineralsfrom the Mount Pleasanttin deposit.Can. Mineral.g, of the innerand outerdou- t66-t79. blets may be regardedas the fraction of ferric and Bnocrwnv, L. O. (1934) The crystal structureof stannite, ferrousions in thesesites. Accordingly, the zinc-free CurFeSnS..Z. Kristallog r. 89, 434-441. stannoiditeis provedto containtwice as much ferric CHeNone,R. D. K , nuo S. P. Punr(1968) Mdssbauer studies of ion as ferrous ion and can be expressedas chafcopyrite.J. Phys.Soc. Japan,24,394l. Cul+Fel+Fd+Snl+S?z-. DoNNly,C., L. M. Conlrss,J. D. H. DoNNAy,N. Er-llorr,eNo J. M. HesrrNcs(1958) Symmetry of magneticstructures: Mag- Theouter doublet corresponding to the ferrousion neticstructure of chalcopyrite.Phys Reu.ll2, l9l7-1923. of the syntheticstannoidite has a largerabsorption ErsscHurz,M., E. HERMoN,eNo S. SHrnrrprnN(1967) Determi- peakthan that of thenatural material containing 2.90 nationof cationvalences in Curs?FerreSnSnby Mdssbauer effect mole percentof zinc ion, while the absorptionin- and magneticsusceptibility measurements. J. Phys.Chem. Sol- ids. 28. 1633-1636. tensitiesof the innerdoublet has about the samein- Everus,H. T. Jn., D E. Appr-rueu,,cNp D. S. HnNnwenrsn tensityin bothspecimens. This suggests that zinc sub- (1963)Program and Abstract42. Am. Crystallogr.Assoc. Meet. stitutesonly on ferroussites in stannoidite.The above Cambridge. valuesindicate 70.6 percent of zincsubstitution in the Gnesnwooo, N. N., ruo H. J. Wurrnrer-o(1968) M

mawsonite in the USSR. Doklady Akad. Nauk ,S,S,SR,192, SpnrNcrn,G (1968)Electronprobe analyses of stanniteand re- 98-t0t. latedtin minerals.Mineral. Mag.36, 1045-1051. Lre, M. S., S. T,rxENoucHr,AND H. lnnt (1974) Occurrenceand - (1972)The pseudobinarysystem Cu,FeSnS.-CurZnSnSn paragenesisof the Cu-Fe-Sn-S minerals, with referenceto stan- and its mineralogicalsignificance. Can Mineral. ll, 535-541 nite, and stannoidite and mawsonite. J. Mineral. Soc. Japan,ll, SrrnNHeruen,R M. (1963)Quadrupole antishielding factors of I 55- I 64. ions.Pftys Reu.130, 1423-1425 Lrvv, C C. (1967) Contibution ir Ia min6ralogiedes sulfuresde Srdcrlrn, H. A., nNo H. S,cNo(1968) Nuclear monopole and cuivre du type Cu3XS.. Mbm. Bur. Rech. geol. minieres, 54, quadrupolehyperfine interaction in organo-tinhalide and or- 35-7 4 - gano-tin perfluoro compounds Trans. Faraday. Soc. 64, MnnpuNrN, A. S, eNo A. R MKRrctlv,r'tt (1967) Miissbauer 577-58l. u'Fe spectra of in sulfides. [transl.] Geochem.Int. 4,980-989. SwrerunN,T. R., nNoJ. V. P. Loic (1969)Quantitative electron- MARKHAM.N. L.,qNo L. J. Lnwneucr (1965)Mawsonite, a new probe microanalysisof rock-formingminerals. J. Petrol. 10, copper-iron-tinsulphide from Mt. Lyell, Tasmaniaand Tingha, 332-3'79. New South Wales.Am. Mineral.50,900-908. Wnlxrn, L R., G. K. Wcnrunn, nNo V JecceRINo(1962) OeN, I S (1970)Paragenetic relations ofsome Cu-Fe-Sn-sulfides Interpretationof the "Fe isomer shift. Phys. Reu. Lett. 6, in the Mangualde pegmatite, north Portugal. Mineral. Deposita, 98-t0l 5. 59-84. W,qrsoN,R. 8., (1960a)lron seriesHartree-Fock calculations. P,,,ur-rNc,L., lNo L. O. Bnocrwlv (1932)The crystalstructure of Phys Reu.l18, 1036-1045 chalcopyrite CuFeS,. Z Kristallogr. 82, 188-194. -(1960b) Iron seriesHartree-Fock calculation ll. Phys.Reo. Psrnux, w (1973) Tin sulphidesfrom the deposit of Brunswick ll9. t934-1939. Tin Mines Limited. Can. Mineral. 12, 46-54. Rnvoonn, P. (1960) Die Erzmineralien und ihre Verwachsungen. Akademie-Verlag,Berlin, 826 p. SnrnNer.8.. eNo A. Y. C. Wouc (1968)Calibration of the'?Fe Manuscript receioed,June 18, 1975; accepled isomer shift Phys. Reu. 166,348-349. for publication, Nouember4, 1975.