Canadian MineralogistVol. 17, pp.125-135 (1979)

AssrRAct

Within the system Cu-Fe-Zn-Sn-S, stanniteCu:(Fe,Zn)SnSa, kesterite Cug(Zn,Fe)SnSa; rrow-sonits CuuFezSnSe, stannoidite CUB(Fe,Zn)sSn2S.,and a number of stannite variants have beenstudied by Gandolfi X-ray camera and electronmicroprobe. In all the examined samples, the com-pounds are stoichiometric with no significant posi-tional disorder, a result confirmed by structurerefinements. Despite appreciable (FeZn) and(Zn,Fe) substitutions in stannite and kesterite re-spectively, observed variations of lattice parameterswith composition confirm the miscibility gap. "Zin-cian stannite" (Berry & Thompson 1962) is a mix-ture of kesterite with exsolved stannite. The 'hn-

known phase" of Petruk (1973) is a mixture ofkesterite and stannoidite. X-ray powder pattertrs,reflectivity and microhardness data are provided forspecimens utilized in the structure refinements ofmawsonite (Szymariski 1976) and stannite andkesterite (Hall et al. 1978).

Sorvrvrerns

On a 6tudi6, au moyen de la chambre d rayonsX Gandolfi et par microsonde, les phases suivantesdu systBme Cu-Fe--Zn -Sn-S: statrnite Cuz(Fe,-Zn)SnSa, kesterite Cue(Zn,Fe)SnSa, mawsoniteCu6Fe2SnSs, stannoidite Cus(Fe,Zn)rSnfi2, ainsique quelques variantes de stannite. Toutes sontstoechiom6triques, pratiquement sans aucun d6sor-drs de position, ce que confirme I'affinement desstructures. Quoique les substitutions (Fe,Zn) de lastannite et (Zn,Fe) de la kesterite soient consid6-rables, la variation des paramdtres r6ticulaires avecla composition confirme la lacune de miscibilitd.La "zincian stannite" de Berry & Thompson (1962)est un m6lange de kesterite et de stannite d6mix6e.La phaso inconnue de Petruk (1973) est un m6-lange de kesterite et de stannoidite. On pr6senteles diagrammes de poudre et des donn6es sur lar6flectivit6 et la microduret6 d'6chantillons de maw-sonite, de stannite et de kesterite qui ont servi irl'affinement des structures (Szymariski 1976, Hallet al. t978).

(Traduit par la R6daction)

*Present address: &partment of Geology, Lake-head University, Thunder Bay, Ontario P?B 5E1.

NEW DATA ON STANNITE AND RELATED TIN SULFIDE MINERALS

S. A. KISSINS eNP D. R. OWENS

Mineral Sciences Laboratoies, CANMBT'Depafiment ol Energy, Mines and Resources, Ottawa, Ontario KIA OGI

INtnoPuctloN

The first description of stannite, ideallyCuzFeSnS4, is generally credited to Klaproth(L797). Since the recognition of a number of"stannites", as first expressed by Ramdohr(1944), much new information has become avail-able on stannite and related minerals in the sys-tem Cu-Fe-Zn-Sn-S that possess tetrahedrallycoor.dinated sulfur atoms. This new informationhas been summarized by Ramdohr (1960), Moh& Ottemann (1962), LEw 0967), Springer(1968), Petruk (1973), Kato (1974) and Lee etal. (1974). The present paper complements theforegoing with new data obtained in the courseof mineralogical studies prior to crystal-struc-ture refinements at CANMET. Specimens suit-able for the refinements were obtained: maw-sonite (Szymafrski L976), stannite and kes-terite (Hall et al. 1978); however, the miner-alogical study was expanded to tackle a num-ber of other problems.

Figure la illustrates the variable metal con-tents and formulae of the minerals in thesystem Cu-Fe*Zn-Sn-S. The diagram does notshow the metal:sulfur ratios; the minerals wouldnot lie in the same plane if a sulfur apex wereadded. Figure lb illustrates the ranges in Cu/(Cu * Sn) vs. Fe/ (Fe f Zn) ratios of the min-erals. The most copper-rich mineral is maw-sonite CuoFezSnSe (Markham & Lawrence 1965).The original formula' CuuFerSnSto, was revisedon the basis of irnproved analyses by L6vy(L967), Springer (1963) and Petruk (1973)'Although Kachalovskaya et al, (1973) reporteda mineral with the formula C'uz.aoFeSno.glsa.otunder the name mawsonite, the analysis totaled104.3%i therofore, the analysis likely reflectsanalytical errors rather than nonstoichiometry.Mawsonite, as noted by Markham & Lawrenceand L6w, is obviously equivalent to the "orangebornito" first described by Murdoch (1916)and to some orange bornites described by anumber of later workers.

Stannoidite was originally considered to beCur(Fe,Zn)fnSe or CusFe:SnSe (Kato t969).Kato also suggested that stannoidite is equivalent

t25

126

( o )

THE CANADIAN MINI]RALOCIST

( b )

O |Mlh Cu€FolSnSo

O siomldito C!0(Bln,3 Snase

\O Et@ilo Cu2(F€,Zn)SnS4

qrd loslsrlt! Cu2(ZnrFo)SnSa

\ \O .hodGt@rtl6 Cu2FoSnlSo

ga,+5o

f(-)

rMtt€

sl,qnddlls

stmll€

rhqtoslonn ito

0.6

0.4

0.!

o.8

o.7

o,2

o . l

oo

Fe l .Zn

Flc. l. (a) Triangular Cu-(Fe+Zn)-Sn diagramPetruk 1973). This diagram displays only thesulfur ratios are not shown. (b) Cu/(Cu-fSn)Cu-(Fe*Zn)-Sn-S (after Petruk 1973).

to hexastannite (-stannitc l) of Ramdohr( 1960), which was givcn the formula CusFeSnS,(details of analyses were not provided), and tosome yelfow stannites (stannite jaune) rJescribcdby a number of earlier workers. Rccalculatcdanalyses of hexastannite by Markham &Lawrence (1965), L6vy (1967) and Boorman &Abbott (1967), together with the hexastannitcformula derived by Springer (1968) and thcstannoiditc formula obtained by Petruk (1973),confirm that the correct formula for stannoiditcis Cus(Fe,Zn)rSnaSrz, a composition now ac-cepted by Kato (1974). Kachalovskaya et al.(1973) reported finding stannoiditc with thcformula Cus.or( Fe,Zn) r.gSflS6.na; however, thiscomposition is more likely the result of analy-tical error, as their analysis totals only 9'7o/o.Previous work summarized by Petruk (1973)indicated that stannoidite ranges in composi-tion from CurFc,rSnaSrz to CurFerZnSnaSr:.

Pctruk (1973) described a mineral from theMount Plcasant deposit, New Brunswick, withthe approximate composition CursFeZnrSnsSzaas an "unknown phase". This phasc. resxamincdin the prescnt study, was found to be a mixturc,as discussed below.

Stannite has long bcen known to contain ap-preciable zinc, such that its formula might bcbetter written Cus(Fe,Zn)SnSa. Petruk (1973)found varicties containing up to 55 at.o/o Znin the (Fc,Zn) sitcs. Kcsterite, Cuz(Zn,Fe)SnS",

o:r 02 o.3 0.4 05 0,6 0.7 o.a m ro

Sn Fe/ f fe*znlfor minerals in the system Cu-(Fe*Zn)-Sn-S (aftervariations among the metals; differences in metal:-

vs Fe/(Fe*Zn) for minerals within the system

named hy Orlova ( 1956), can also contain ap-preciablc iron. Pctruk found kcsterite with asmrtch as 55 aL% Fe. Thc problcmatic struc-tural stability relationships between stannite andkcsteritc are lhe subject of much of the presentpapef.

Isostannite, optically isotropic and possiblya polymorph of stannite (Claringbull & Hey1955), sakuraiite, the indium analogue of kes-tcritc (Kato 1965) and rhodostannite (Springer1968) wil l not be discussed in this paper.

Mr'.rnons oF SrUDY

Obtaining accuratc analyses was initially di.f-ficult because the use of binary sulfide orclemental stanclards often yielded anorhalottslyhigh or low atomic proportions in analyzedminerals. Improvement over earlier analyses inthis laboratory and most literature analyses wasattained by production of synthetic CurFeSnSeand Cu:ZnSnS.r standards. In each case, thestoichiometric proportions of the pure elementswere heated for 2O days at 800"C in sealed,cvacuated silica tubcs. The tubes were thenquenched in ice water and the reaction productswero ground in a mortar. The products of theinitial reaction were then placed in a verticalfurnace in sealed, evacuatd silica tubes withsufficient flux of NaCl and KCI ( I : I on molar

oo

r27TIN SULFIDE MINERALS

basis) to completely immerse them and heatedto 800oC for 4 days. The final quenched prod-ucts consisted of CurFeSnSr and CuzZnSnS",with traces of SnS. X-ray powder and single-crystal studies also showed the synthetic prod-ucts to be structurally identical to the naturalminerals. The synthetic materials were com-pared with natural stannite and kesterite withthe microprobe; intensities obtained for CuKcy,SnLa and SKa peaks were identical.

Specimens examined in this study were anal-yzed on a Materials Analysis Company (MAC)Model 400 electron microbeam analyzer op-erated at 25 kV and 0.03 pA specimen current.The compositions and homogeneity of thespecimens were determined from data acquiredby collecting counts for 10 s periods from 5 tol0 spots on a grain. Stannites and kesteriteswere analyzed for Cu, Fe, Sn and S by meansof the CuKa, FeKcr, Snlcu and SKa lines ofthe CusFeSnSr standard and for Zn using theZnKa line of the CugZnSnSa standard. Maw-sonite was analyzed using CueFeSnS.r and theFeKa, SnIa and SKa lines; copper was deter-mined using the CuKa line of CurFeSnSn or byaveraging the values obtained using CurFeSnSe,synthetic CuSe, synthetic CuFeSs and naturalchalcopyrite. Copper in stannoidite was deter-mined in the same manner, or by usingCurFeSnSe alone. as were Fe, Sn and S. TheZnKa peak of synthetic CuZnSnS, or syntheticiron-bearing ZnS was the standard for Zn.Minor Ag, Cd and Mn were determined usingAgLa, Cdla and MnKa of the pure metalstandards. Indium was determined using InLaof synthetic InAs, and Se using SeKa of syn-thetic CuSe. The data were reduced by meansof the EMPADR VII program of Rucklidge &Gasparrini (1969).

All X-ray powder data were obtained bymeans of a 1L4.6 mm Gandolfi camera. as itssmall sample capacity provided the best meansof obtaining impurity-free patterns. FilteredCoKa radiation (tr = 1.79021A) was em-ployed; d values were also calculated for re-solved CoKa, (tr = 1.788904) and CoKas(tr = 1.792784) reflections. Relative inten-sities were estimated visually. Lattice parameterswere obtained by means of the PARAM least-squares refinement of Stewart et al. (L972).

Reflectances were measured in air using aLeitz MPE microscope photometer with asilicon reference standard (N 2538.42, issued bythe IMA Commission on Ore Microscopy).Microhardnesses were determined on a LeitzDurimet hardness tester using 50 g for 15 s,

SreNNrrr exo KEstnnttr

Stability relationships between stannite andkesterite have an important bearing upon thecharacterization of the minerals, as it is neces-sary to know whether composition alone is suf-ficient to distinguish the two. Experiments byMoh (196,0), cited without details but lateramplified (Moh 1975), indicated complete solidsolution between the two minerals at 700'Cin dry systems and at 800'C in NaCl-KClmelts. Springer (1972) confirmed the high-temperature solid solution, but he found amiscibility gap in the CufeSnSo-CuZnSnSnpseudobinary system that appeared at 680oC onthe iron-rich side and extended to zinc-bearingcompositions at lower temperatures. He des-ignated the solid solution above the 680oC in-version B{uz(Fe,Zn)SnS, and the lower tem-perature, iron-rich phase a{ur(Fe,Zn)SnSa. Inthe solid-solution regions of the phase diagram,Springer found that the lattice parameters ofthe two phases were distinct, with 2a=c inB-Cuz(Fe,Z\)SnSr and with 2a exceeding c by

,,,,,$**-e-*-e-*e*{! ao 4sss g

frxlefs$s

*YS

s 4 @ ' n^ " , . _ . @ _ $

& 6 # . p . 1 S

; "@*;*de-#*

, .".* ,q.

r iF* **@<"s- - * - * t

R *:s* urff i t :

, " $ . ' ",i -.'.;\,

Ftc. 2. Specimen from Omo, Bolivia (ROME1769, grain 2R) showing stannite core (lighter'with cleavage) and kesterite rim (darker). Oilirnmersion.

* - : . * ' * L * #w***wre

tzg THE CANADIAN MINERALOGIST

0.194 in a{ur(Fe,Zn)SnS.r. The B{ur(Fe,-Zn)SnSa phase is apparently isostructural withkesterite; however, the a{u!(Fe,Zn) SnSa phase,although possessi-ng lattice parameters similar tothose of stannite, differs from stannite in thatits X-ray powder pattern contains extinctionsnot permitted in Brockway's (1934) model ofthe stannite structure. Springer was uncertainwhether the lattice parameters of the a and llphases converged near the miscibility gap. Ifa-Cue(Fe,Zn)SnSr is equivalent to stannite, aswas assumed by Harris & Owens (1972),Petruk (L973) and Moh (1975), thenSpringer's (L972) solvus implies the existenceof stannite and kesterite with identical composi-tions. Petruk (1973) found a range of over-

lapping compositions with respect to (Fe.Zn)solid solution in the two minerals in his studyof natural specimens. The foregoing indicatesthat differentiating stannite and kesterite wouldbe difficult both on a compositional and struc-tural basis in the absence of additional informa-tion.

Stannile and kesterite in a coarsely crystal-line core-to-rim relationship (Fig. 2) were usedior the structural refinements. Crystal frag-ments extracted from the field of view in Fig-ure 2 provided Gandolfi X-ray data whichclearly differentiated the two minerals, andthese fragrnents ultimately were used in thestructural work (Hall et al, 1978), The powderpatterns are compared with those of synthetic

XABI.E I. X-NAY POWDER DII'FRACIION DATA FOR STANNITE AND KSSTERITE

Syrthetlc Cu"F€SnS,(80o 'c ) '

q .5 .4432 r 0 .00 l lAc.10.7299 ! 0.00514

StannlterRoil 81769, Cr 2!(3a€5.449 I 0.0024

!"to.zsz . o.ooal

;ynthet lc Cu,ZnSnS,(800"cr - '

r"5.4339!0.0009A].lo.aozgto.ootaA

KesterlterRoM E1769, Gr 2Rl2)4"5 .427 t 0 .001 A

" - . to .e f t . O.ooS i

lrt, d^r- d--, ̂ t/ I d^!- d-. . - t l . rk l t t \ l

tl2) l 3t20r04t2221'14

Il5t20t24r31rt06''t 6,

t2434

r40t084 l r

27

i40rt44't25t44{o Is2

2 9 '

52{" I8 2153. 'crr+1" o,

r . 2 . 1 0 -

,40{o r4 2

88{oIs 2

r52(qld 2

a 2

.3 .1 o {o Ic216044r48

r.89J . t l

3.002,7232.678?.4272,369

,. 006I .9831,922r .9081.784 {t .640

29

| lz4'

t.240

| .215t . ? m1 . 1 0 7t . 1 0 9t . t 0 0| .101l .070| ,0471,047t.043|,042,t.034t .033).9987) .971 8 ').9622).9617).9557

) .9198).9200).9167) .9169) .91 05) .91 06

).9058).902r

,623

449389

341310 {

a .2 .2

tosl -t

)013 i

1 3 l l, 9 i721 :t83t27 I374 i

)1, I196,25i l l I189 r788t39 |

; f t 't64 1449 lt0 t

5 0 1341l l 0310297

,aa -

240) f

217214203t08t08100 it00 l)7L lA7 l)47 ))42141 I

)37 J)942 l)727 I

)622 l

)197 :)197 1n66 t

n06 I)106 i

14 .6v 4 .&| 3 . r 3 3 . 1 3 l 01 3 . 0 1 3 . 0 0 r12.718 2.726 \

| 2.681 2.6se 2

ln36 L3.a -

12.202 2.205 11

l r.ool ,-oor -T

t _ _ _I r .sra r .9r4 7I

l , - , ; ;l r .ozz t l ' ! ! l 4I r .563 1.566 r

t12r20.)04r1201124'

l6 rt24140r)08,132r

r40t44t28t44\

'

tza'52r36.1 .r 0.'40.t48Jt5256

t 1 n

3 . 1 3 3 . 1 4 l 02 ,715 2 ,717 6't,920 1.921 9'1 .640 r .638 B'| .567 1.569 I1 .354 I .359 2

1 .246 1 .247 4

1 . 1 1 0 1 . 1 0 9 5

'1 .047 1 .045 5

0.9600 0.9605 4

0 .9186 0 .9185 6

3 . 1 3 3 . 1 3 l 02 .701 2 .712 3

1 . 9 1 3 1 . 9 1 8 5

I .53$ 1 .636 7I .571 1 .566 t .' t .358 r .356 I

1 ,245 1 .245 3

' t . 2 t 3 r . 2 1 3 I

1 . 1 0 8 t . t 0 7 3

t.045 I .044 3

0 .9589 0 .95& 1

p.9178 0 .9169 :1 2! .9178 0 .9169 o2 I1.303 I .3C0 '2'1.273 1.269 \

1 .250 1 .250 |t.uz tl'.1!l 6, ^ , ^ . 1 . 2 1 9' ' " ' " I 1 . 2 1 5 tI .209 1,206 \' 1 . 1 0 9

1 . 1 1 0 3' 1 . 1 1 0 1 . 1 1 0 t 1

1 . 1 0 2 I . 1 0 3 31 . 1 0 2 1 . 1 0 3 t

r .048 r .049 I

1 .044 1 .043 I1 .043 1 .043 t1I .038 l .036 21.037 I .036 ta

r .363 1.363 r1,342 L344 2

, . * t " * ,

;0 .9574 0 .9571 30.9573 0.9571 r

0 .9214 0 .92 t0 20 .9179 0 .9182 30.9177 0.9182 20 .9125 0 .9125 40.9123 0.9't25 20.9087 0.9085 ta

.O.gO:O O.gO:O ",2to.9o3z o,9o3o a;l

* Lattlce parameters frcm stroctlrere f lnsents o f Ha l l g !91 . (1978) .Errcr tems ln all cases are standarddeviations.

t29TIN SULFIDE MINERALS

TAELE 2. TLECTRON }IISROPROAE AMLYSBS OT STANMTE AND TSSTERIE

SepLe aod localltyltelght per cent lotaX

At@lc DroDottlorac E f 6 E z a 6

STNNIM

1. &u!o, BollvlaROll E1769, Cralu 6-2b

2. Orulo, BollelaRoil 81769, Gretd 2R (3)

3. Levack west olne, Sudbury,ht., CAI{WT conceDtrate

4. Orulo, b1lvtacSC 14738, crain 3

5. Oruto, Bollvla, San Jos€6tn€, Roil M190349

6. le orshaDler deposlt(@teray, 8.c. , RU V8. lA

29,2 -- r l .3 --- r .8 -- 28.0 29.7

29.5 --- 10.5 - 2.7 0.43 27.8 29.9

29.a -- 10.8 --- 2,7 0,04 2A.0 2?.7

29.6 -* 10.8i -- 2.2t O.tL 27.7 0.03 29.7

2 9 . 5 n . d . 1 1 . 9 _ _ _ 1 . 5 _ 2 6 . 2 * 1 1 . 3 3 r i 3 0 , 3

2 9 . 1 0 . 1 5 1 1 , 5 0 . 1 0 2 . 3 n . d . 2 7 , 5 o . d . 2 9 . 9

100.0

r00.8

1 0 1 . 0

100.1

100.8

r.00.6

1.99 0.88 0.12 L.02 4.0{

1.99 0.81 0.18 0,02 f.oo 4.0(

2.01 0.83 0.18 0.00 1.01 3.9t

2.01 0.86 0.14 0,00 1.01 0.00 4.(X

1.98 0 ,91 0 .10 0 . r4 0 .05 4 .0 :

1 .96 0 .88 0 .01 0 ,15 1 ,00 4 .01

KESTERITE

7. tuuto, tullviaRoM 81769, craln 2R (2)

8. Zl6sa1d, bhsla, Czech.IISNU C5233, eraln 1

9. oruro, tollalaRou 11769, crsln 2R

10. zlndseld, tuh@la, Cz6ch.gSNl{ q5233, Ctaln A

i1. zrnnetd, }oh@le, czech.USNil C5233, cratn B

12. lfugo Dlne, (eystooe,s. Dakota, sDs!{&T 5099

29.L -- 3.7 -* LL.r O.22 27.3 29'7

3 0 . 0 - - 6 . 5 0 . 0 2 7 . 8 0 . r 7 2 6 . J 0 . 0 7 2 9 . 9

3 0 . 2 - - - 4 . 1 0 . 0 9 9 . A 0 . 2 5 2 6 . 0 0 . 1 1 2 9 . 4

2 9 . 7 - - 6 . 3 0 . 0 8 7 . 5 0 . L 7 2 6 . 3 0 . 0 4 2 9 . 6

2 9 . 0 - - - e 2 . 3 0 . 0 3 1 0 , 9 L . 6 7 2 7 . 1 2 9 . 7

1 0 1 . 1

1 0 1 . 0

t-01.6

100.0

99.7

1 0 0 . 7

1 . 9 8 0 . 7 3 0 . 2 9 0 . 0 1 0 . 9 9 4 . 0 1

2 . 0 3 0 . 5 0 0 . 0 0 0 , 5 1 0 . 0 1 0 . 9 6 0 . @ 4 . q

L , 9 6 0 . 2 7 0 . 7 6 0 . 0 1 0 . 9 9 4 . 0 i

2 . O 7 0 . 3 2 0 . 0 r 0 . 6 5 0 . 0 r 0 , 9 5 0 . 0 0 3 . 9 !

2 . 0 J 0 . 4 9 0 . U ) 0 . 5 0 0 . 0 0 0 . 9 5 0 . 0 0 4 . 0 :

1 . 9 9 0 . 1 8 0 . 0 0 0 . 7 3 0 , 0 7 1 . 0 0 4 . 4 )

r Avetege valuesi sll.ght vatiatlon zo F 1.7 to 2.72 6na Fe o U.2 to 10.22 {t.t rAve la8e la lues i s118ht ver la t lon I t r F 0 .54 to 2 ,047 and Sn '27 .4 to 25 .22 f t .

@ Stlve! could lot be detehloed because of secotrdary f1lorescdce fl6 nlnute locluslons of an 61Bdent1f,1ed alleei-batlng Phaae.

Sp€clden no. 5 tas taten fr@ the tuple used ln derlvlDg Berly 0 ThoEpBoa'E (1962) pattefr fo! sta@lte (rc. 69). thfu 16 th€

fj.rat eDalysls of thla apeclaen.o.d. aldotes dot alelecteal (1lolt of derectloa I O.02Z rt.); ROlts tuyal htallo hse@i USW- Untted States Natloml !iise@,- SElthsnleo

Insttrutloai cSC F Ceologlcel Sutrey of &frda; SDSWT = ituse@ of G6ology, South Dakota of Ulnes E TelEologyi n.f. - R. lrdugan' CSc.

Cu,FeSnSa and CuZnSnSa from this study inTable 1. Compositional data for the naturalspecimens are provided in Table 2 and reflec-tances in Table 3. Misrohardness indentationscould not be obtained, as grain mounts con-taining the minerals fractured excessively.

Powder-pattern differences between stanniteand kesterite are subtle but distinct. Both aretetragonal with the same permitted reflections,h+k+l - Zni however, kesterite is stronglypseudocubic. Lattice parameters derived in thestructural refinements (Hall et a/. 1978) showthat stannite 2a exceeds c by about 0.lA where-as kesterite c exceeds 2a by only 0.01A. fhedifference between 2a and c in kesterite cannotbe determined by powder methods, and its

TABLE 3. REFLECTANCES AND ltlICRo-INDENTATIoN HARDNESSOF STANNITE, KEsTERITE AND IIAIISONITE

470 545 589 650

26.1 ?7,2 27.4 ?7.427.6 28.0. 28.2 27.6

24.3 23.8 23.8 24.7

19 .5 22 .6 24 .5 28 .314.9 20,3 24.9 31.6

21 ,2 24.0 25.6 ?9.617 .7 22 .8 28 .3 34 .5

tetragonal symmetry can be determined only by

singli-crystal methods. For example, (020) and(OM) form a closely spaced diffraction coupletin stannite and are unresolved in kesterite' Anu.mber of such resolved and unresolved coupletsclearly distinguish stannite from kesterite'

To determine the effect of composition onthe lattice parameters of stannite and kesterite,carefully selected specimens from worldwidelocalities were analyzed (Table 2), and X-rayedwith a Gandolfi camera. The cell dimensionsoI kesterite were refined by indexing with apseudocubic cell of lattice parameter c. Thisprocedure t}ten assumes 2a = c, so that theiesults are useful only for comparison with thelattice parameters of stannite. Figure 3 shows2a and c v,r. composition of the (Fe * Zt)sites in the stannites and kesterites from Table2. Parameters of the pure' synthetic end-mem-bers from this study are also included. Minoramounts of Mn have been added to Fe andCd to Zn in normalizing the atomic contents ofthe (Fe f Zn) sites to 1.000.

These studies of well-characterized specimensshow that stannite and kesterite are structurallydistinct (Fig. 3). Lattice parameters show notendency to converge as a function of solidsolution, although the pararneters of stanniteincrease slightly with increasing solid soltrtionof Zn. and those of kesterite decrease slightly

Wavelenqth (nm)

stannlte' oruro' Bol lvia(R0M E1769, grain 2R[3])

KesterJte, oruro, Bol iv ia(Ro|'t El76e' grain 2R[2])

I,lawsonite, Ikuno mlne'Japan (Nli'lNH 122102)

!{awsonlte, Kidd creekm ine ,On ta r i o(Rrr rQ 74-68lul)

.RoRA,.o

ao

.Ro8c

l4awsonlte, Kidd Creek mine specimen: mlcro-lndentinghardness (rnean of thr€e nEasurements) VHN59, 240 I 19

130

with increased Fe in solid solution. Figure 3does not purport to illustrate the entire rangeof solid solution of both minerals; more ex-tensive solubilities of Fe and Zn in kesteriteand stannite, respectively, have been reportedin the literature. However, the results shownhere do indicate a miscibility gap between thetwo minerals, and suggest that they possessdi.fferent crystal structures. The latter conclu-sion has been confirmed by Hall et al. (1978),who refined the structure of stannite in spacegroup I42m and kesterite 14.

Also demonstrated by these well-character-ized specimens is that neither stannite nor kes-terite exhibits nonstoichiornetry beyond -+57oin any alomic position in the idealized formuiaCur(Fe,Zn)SnSe. The small divergences are at-tributed to analytical error. These data stronglysupport the structural model of Brockway(1934) Ior stannite, 1.e., ordered sites in spacegroup 142m, and further indicate that the con-tents of the atomic positions in kesterite areordered.

The detection of kesterite, often unnoted ormisidentified, in a number of museum speci-mens studied in this investigation indicates thatthe mineral is probably more common than

o<

.g

q,

oEooo-c,

.o

5

THB CANADIAN MINERALOGIST

Fe (+Mn ) : t.ooo o'soo zn (+ cd): t.ooo

Conlenls of the (Fe +Zn) Site

Frc. 3. A plot of 2a and c lattice parameters vs. the composition of the(Fe-FZn) sites in staDnite and kesterite. Sample numbers correspondto those in Table 2; synthetic end-members are from this study. Mnhas been added to Fe and Cd to Zn and the atoms in the (Fe*Zn)position have been normalized to 1.000. Solid symbols are the syntheticend-members.

previously suspected, perhaps nearly as com-mon as stannite. Kesterite should be suspectedwhere isotropic or nearly isotropic 'ostannitesn'

are noted.Although stannite and kesterite may be dis-

tinguished in polished section, particularly inlreshly polished sections under oil immersion,the etching technique employed by Harris &Owens (1972) was found to be extremely use-ful in differentiating the two minerals in inter-growths. A 1:1 solution of HNOg etches stan-nite and attacks kesterite much more slowly.Caution is necessary in interpreting the etchedsection. as the etchant also attacks twinnedcrystals differentially.

THr Pnoarsvr op STaNNITE VARTANTs

Zincian stannite

Berry & Thompson (1962) applied the term"zincian stannite" to a specimen from theSnowflake mine, Revelstoke, British Columbia.They noted that the X-ray pattern (No. 70)of this mineral differed from that of stanniteand required difderent cell dimensions. ThePDF listing (21-883) presently applies the

E

otr

Typicol ermr limifs qt lo-

TIN SULFIDE MINERALS 1 3 1

Berry & Thompson data to kesterite, soidentity of zincian stannite .and kesteritebeen assumed.

The Berry & Thompson specimen (UT R218)that gave pattern No. 70 was found to consistof massive kesterite with copious lamellae ofexsolved stannite (Fig. 4). Analyses of thetwo minerals are given in Table 4. The powderpattern is that of kesterite with several reflec-tions of stannite. The kesterite reflections aloneyield lattice parameters intermediate to thoseof stannite dnd kesterite, possibly because stan-nite and kesterite reflections are not resolvedin a mixture o,f the two minerals, even thoughtheir lattice parameters differ slightly. Theeffect on unresolved reflections would be toshift d spacings towards a mean value.

The Berry & Thompson X-ray powder pattern(No. 70) is therefore suspecto as it may containreflections attributable to stannite and likelv will

TABLE 4. ELECTRON MICROPROBE NALYSIS OT "ZINCIAII STAITNITE'Tthathas

rfif crsfls! { { lL ; r$ . }$ t } f : : : : . .1 . : : sd ,+ : . r .

Frc. 4. Specimen from Snowflake rnine, Revelstoke,British Columbia (UT R218), identical to zincianstannite of Berry & Thompson (1962). Theetched (l:1 HNq) left side shows exsolvedlamellae of stannite (etched) in a kesterite host(unetched). Crossed nicols, oil immersion.

-!fa'|! j.te_0_CnF_X-ee)

29.3 ut. %0 . 1 I8 .2

0.28n .d . *

a t , l0.' t2

29.5t00l

t unlverslty of Toronto collection, UT Ml8; * not detected(i.e., < 0.02 wt. %). Formulae are based on a totai of eightatons. Kesterlte host:( cu2.99Aes.92 ) 12. oz( Zno.64Feo.35)ro. gg (snt . ooIno.0l ) r l , ot

-

53.99i stanni te larFl lae:cuz. o0( F"0.642n0. socdo. ot ) r t .0tsno.9953.99

not yield the correct lattice parameters forkesterite. Preferred data are those obtainedeither from topotype kesterite by Ivanov &Pyatenko (1959), or from the Oruro (Bolivia)specimen (No. 7) used in this study and inthe refinement of the kesterite structure.

Petruk (1973) employed the term "zincianstannite" for stannites containing from 40 to55 at./o Zn in the (Fe * Zn) Sites. This usageis in accord with mineralogical practice butit conflicts with the prior usage of Berry &Thornpson (1962). As well, Petruk foundsignificant nonstoichiometry in his specimensin that they contained excess (Fe * Zn) anddeficiencies in Cu or (Sn * In) or both. Oneof us (D.R.O.), who was Petruk's analyst, be-lieves that the deficiencies are analytical andaross principally from the use of binary sulfideand elemental standards. However. if Petruk'szincian stannites are truly nonstoichiometric,they are likely not isostructural with stanniteor kesterite and therefore represent some here-tofore undescribed species. Unfortunately,Petruk's specimens are too small to be usefulfor further study. In any event, the term "zin-cian stannite" probably should be avoided inview of the conflicting usages to which ithas been subjected.

Ferrian kesterite

Petruk (1973) applied the term fenian kesteriteto kesterite containing 25 to 55 at, Vo Fe in the(Fe *Zn) sites. This range seems to be normal,and complete solid solution to the CuZnSnSaend-member is well established. Petruk's ferriankesterito differs slightly in reflectivity and sub-stantially in microhardness from low-iron kes-terite. The most iron-rich kesterites reportedin this study (Nos. 8 & 11, Table 2 & Fig. 3)

ElementCuAgFeZn

MnSnln

Kest€ni te .( host)29,0 ut, %0.424 . 49 . 60 . 1 0 .n . d . '

27 .00 . 1 3

29,299 .8

!$l!! r l !a)'::.

:*t1 . -

t;1 ,

ij:;',

#

t32 THE CANADIAN MINEMLOGIST

aro similar in composition to those reportedby Petruk. The problems relating to these high-iron compositions and the role of indium willbe treated in a subsequent paper.

"Unknown phose"

A mineral compositionally intermediate be-tween stannoidite and ferrian kesterite wasreporred by Petruk (1973). His polished sec-tion, No. 52-523, was borrowed and the grainillustrated in his Figure 11 was relocated. Migro-probe analysis yielded results similar to thosereported by Petruk and indicated homogeneity

with respect to the electron beam. However, inthe course of the study, an improved X 100objective with a flatter field of view was ob-tained and the grain was re-examined. Thegrain consists of an extremely fine, oriented,lamellar intergrowth of stannoidite and kesterite(Fig. 5). The apparent composition of the mix-ture can be represented by the following egua-tion: CuaFeZnSneSra (high-Zn stannoidite) *3CuZno.ozFeo.sgSnsa (ferrian kesterite) =CureFeZngSnrS:a. Ramdohr (1944) shows sim-ilar intergrowths, although somewhat coarser,in material from Zinnwald. He identified thetwo components as stannite I and II. Similartextures were found in material from Zinnwaldin the present study. The two minerals arestannoidite and kesterite. The "unknown phase"of Petruk (1973) is an example of a "micro-probe-homogeneous intergrowth" that occursnot too infrequently, though rarely expressedas a warning in literature (Scott 1976).

SteNNonttB

Stannoidite from two localities was analyzed(Table 5). The mineral seems to be stoichio-metric Cue(Fe,Zn)gSnsSrr, in agreement withthe structural refinement of Kudoh & Tak6uchi(t976), who determined that the unit cell ofstannoidite contains 25 atoms with the accaptedformula. The ratio Fe/Zn in the present analysesranges from 2:1 to 3:0, in agreement withearlier observations as well as those of Yama.naka & Kato (1976). Their Miissbauer studyshowed stannoidite to have the ionic formulaQgl +spge+rpgs+Sna+u,S2-rc. Zinc apparently maysubstitute only for Fe2+, giving rise to theobserved Fe/Zn ratio in the mineral.

TABLE 5. ELECTRON MICROPROBE ANALYSES OF STANIIOIDITE

El ement

' r . ' . t**

CuFe7n5n

( a

Ikuno nine, HyogoPrefecture, ilapan

38.5 wt. %l l . 51 . 6

1 8 . 929.3*

Kidd Creek nine,0ntario38.8 wt. %8 . 54 . 5

1 8 . 029.1l . l

Frc. 5. The 'trnknown phase" of Petruk (1973),ao intergrowth of stannoidite and kesterite(centre). Individual lamellae are less than I s,mthick. The grain is rimmed by chalcopyrite(cp, white), which also occurs as orientedlamellae in the surrounding sphalerite (sl, darkerey). The light grey mineral is tennantite (ten).

9 9 . 8'100.0

* Not detennined. Formulae listed below are based ona total of 25 atoms. SpecinEn from the lkuno mlne isNMNH I08319 (Smlthsonian Inst i tut ion col lect ion):c' I . g'G

" z. agzn'. 33) 23. 'zsnz. ogst t . go' speci ren f rcmthe Kidd Creek mine is TQ 74-5601101 (R.I. Thorpe,kological Survey of Canada) : Crg.OO(F.2.OlZnO.gl)-

r2. gzsnl . gg(sl r . gt seo. r a) rr z. os'

TIN SULFIDE MINERALS 133

MewsoNrts

Both the formula, as discussed earlier. andthe structure of mawsonite have been sutjectsof controversy. The formula CusFesSnSo wasconfirmed in the present study, analyses havingbeen given previously by Szymairski (1976),

The non-cubic structure of mawsonite is in-dicated by its very strong anisotropy. Attemptsby Markham & Lawrence (1965) at indexingthe powder pattern led to a pseudocubic solu-tion. Yamanaka & Kato (1976) proposed thattho structure was tetragonal with space group142m, -I4mm, 1422 or 14122, a 1O.745, ctO,7lLA. Szymariski (1976), however, refinedthe structure in space group P4m2, with a1.6O3, c 5.3584.

Prior to Szy.mafiski's structural refinement,the specimen IRIT, TQ74-681 ( I ) I from the KiddCreek mine was examined mineralogically. Themicrohardness and reflectivity of the mineralwere measured and the latter property com-pared with that of mawsonite from the Ikunomine (Table 3). Szymaiski (1976) provided acalculated powder pattern of mawsonite; anindexed measured pattern given in Table 6 iscompared with data obtained previously byMarkham & Lawrence (1965) and Yamanaka& Kato (1976). Although the agreement amongthe patterns is good, Szymaiski (1976) ques-tioned whether some of the reflections observedby Yamanaka & Kato (1976) were perhapsdue to impurilies. Although Yamanaka's &Kato's reflections at d = 7.62, 1.318 andl3O2A are indexable in Szymaiski's cell as(010), (014) and (M1,152), respecrively,Szymafski concluded from his structural workthat the intensities of these reflections shouldbe too weak to be observed. However, com-parison of intensities on the Gandolfi film withthose of Szymaiski indicates that all but (014)are observable. The intensity of (014) is veryweak according to Szymafiskfs data; but theobserved reflection reported by Yamanaka &Kato is too close to the calculated d value tobe fortuitous. The (012) reflection, as well,was observed in this study, although Szymafrskiomitted tiis reflection as too weak to be ob-served. The 2.4624 reflection observed byYa,manaka & Kato does not agree well withany observed in this study or with the dataof Szymaiski, although it is nearest to (012).The (230) reflection was not reported bySzymaiski, nor was a correlative one found byYamanako & Kato, alfhough Markham &Lawrence reported one at d = 2,Q984, TheCoKBr reflections for (O210) and (222) could

have produced the d - 2.098 A reflection notedhere, but filtration problems were not previ-

TABI,E 6. POWDBR X.RAY DIFF'RACTION DATA FOR I4AWSONITE

1. ldawsonite. Mt. LyelL, Ta€@ia, Auetral la, (Markhi l& I ,aer6nc@ L965), DebyE-sshelrer (co)

2. l{awsonlte, Akenobe alne' Hyogo Plefeclure' 'tapil,(YaMnaj<a & Kato 1976), Dif f ractoreter (culNi)

3. MassonLte, ( tdd Creek elne. l ( ldal Tomship. CochraneDlstr ict , ontar lo ' Ceada I TQ 74-560 (10) l r

g - 7 . 6 0 3 t 0 . 0 0 2 i , 9 - 5 . 3 5 8 1 0 . 0 0 1 4

I!4arsoni te l'la$son ite Mavsonite

dob" r / r roo dob. r / rLoo dob" r/rto d..1" hkl

2

5

4 . 3 7

3 . 0 9

2 . 6 8 0

2 . 1 8 52 . 0 9 4

I . 8 9 5

I . 7 8 8

L ; 7 3 9

1. r t l8

L . 5 4 7

1 . 4 6 0

1 . 3 4 3

2 0

2 0

101 0

r 0 0t 0

1 0

l 0

8 0

8 0

t 0

2 0

7 . 6 2

4 . 3 8

3 . 8 03 . 3 7 83 . 0 9 9

2 . 6 5 4

2 . 4 0 L

tlgez

l . 8 9 9

L . 7 9 1

1 . 6 2 0

L . 5 4 9

1 . 4 6 3

1 . 3 4 4

t . 3 t 8

1 . 2 3 3

1 . 0 9 6

t 0

41 0 0

1 0

I

3

4 0

7

1 0

3. r .0 102 . 8 8 4

5 . 3

3 . 7 0

2 . s 2 ' / ,

2 . 4 L 3

2 . 3 0 22 . L 9 I2 . 0 9 , / ,1 . 9 5 8 | / :r . 8 9 9 7

L . 7 9 0 21 . 7 4 t 2

L . 6 L s 6

1 . 5 s 4 ' / z

L . 4 6 2 2

1 . 4 3 9 , / "

L . 3 6 2 , / "

1 . 2 1 3 , / z

1 . 1 5 5 t / "

1 . 0 9 5 7

L . 0 2 3 t / "

0 . 9 9 6 7 r / z

o . 9 s 6 7 r / "

0 . 9 4 9 1 5

0 . 9 3 6 0 I0 .9291 20 . 9 0 7 9 20 . 9 0 6 6 40 . 9 0 6 8 3

' 7 . 6 0 1 0I s , 4 1 1 0l . 5 . 4 001

4 . 3 8 0 l If 3 ,80 020l : . g o r l r

3 . 4 0 L 2 03 . 1 0 0 2 72 , 8 7 r 2 L

I 2 . 6 9 2 2 0l , 2 .68 002

2. s3 0L2( 2 . 4 0 I 3 0I 2 .40 22L\ 2 . 3 9 \ 1 2

2 . 2 9 0 3 12 , L 9 0 2 22 . L L 2 3 0L , 9 6 2 2 t

I 1 . 9 0 1 0 4 01 , 1 . 8 9 8 2 2 2I r . 7 9 2 3 3 0( 1 .789 L32

! . 7 4 4 r 4 lI L . 6 2 1 2 4 rt 1 . 6 1 7 0 2 31.58L L231 . s 5 0 0 4 2

( L . 4 6 3 0 5 1I r . 4 6 3 3 4 L( L . 4 6 0 0 3 3

1 . 4 3 5 2 4 2I 1 . 3 6 s 2 5 r( r . 3 6 3 2 3 3I 1 . 3 4 4 4 4 0( 1 . 3 4 0 0 0 4

1 . 3 1 9 0 1 4r I . 3 0 4 5 3 0. l 1 .303 L52L 1 . 3 0 0 r r 4I r . 2 3 3 0 6 1t 1 . 2 3 1 2 4 3( I . 2 0 2 2 6 0J 1 . 2 0 1 4 4 2\ 1 . 1 9 9 2 2 4r r . r 5 9 4 5 1

. l 1 . 1 s 8 3 4 3I r . r 5 8 0 5 3\ 1 .146 062( r .o97 262t r . o g s o 4 4f I . 0 3 5 4 6 1i r . .034 063r t - .03r o25(L025 27L1 L , 0 2 4 1 6 3\ 1 . 0 2 2 1 2 5f 0 . 9 9 8 3 3 7 01 0 .9979 L72I 0 .9954 225I 0 . 9 5 7 0 3 6 3( u . t r t J z 5 )

I 0 . 9 5 0 4 0 8 0t 0 . 9488 444

0 . 9 3 5 5 3 7 20 . 9 2 8 8 4 7 L0.9079 4530 . 9 0 6 5 a r 2 4 50.9055u2 245

* Lettfce par@ters flon gtluctule refLneBent of,sz:@ar' tskj .( f976). Elror terc are studard deviat lons.

134 THE CANADIAN MTNERALOGIST

ously observed with our X-ray camera. Aswell, the reflections appear in other powderpatterns and in the calculated pattern usingCuKa radiation (J. T. Szymafiski, pers. comm.).Markham & Lawrence and Yamanaka & Katoobserved a weak reflection at d = 3.34 and3.3784, respectively. Szymafiski stated that thisreflection could not be indexed on his cell,although the calculated value of d : 3.4O4for the (12O) reflection is closest to their values.Although (120) was not observed in the presentstudy, it seems possible that it is an X-ray re-flection of mawsonite and that neither thepattern of Markham & Lawrence nor that ofYamanako & Kato contains reflections at-tributable to impurities.

The strongly pseudocubic X-ray powder pat-tern of mawsonite is explicable if. d = 2cin terms of the unit cell and space group givenby Szymaiski (1976). Thus, for reflectionssuch as (110) and (0Ol) in which (h, +&'),rto, = 2Pcoor> and (h2 * &'),oor, : 2fnnr,the two reflections will be nearly superimposedand unresolved. Although P4m2 has no ex-tinction requirements, the previous conditiongreatly reduces the number of discretely ob-servable reflections.

AcKNowLEDGEMENTs

Tho authors thank Dr. D. C. Harris.CANMET, for providing impetus and guidancefor the study. Valuable discussions were heldwith Drs. L. J. Cabri, S. R. Hall, W. Petrukand J. T'. Szymaiski, all of CANMET. Thefollowing personnel at CANMET provided tech-nical assistance: R. G. Pinard (photography),E. J. Murray (powder X-ray techniques), J.M. Stewart (single-crystal X-ray techniques),J. H. G. Laflamme (polished section prepara-tion and crystal synthesis), Drs. S. R. Hall andD. C. Harris (data reduction), Dr. T. T. Chen(reflectivity and microhardness measurements).We also thank the following for supplyingspecimens: Drs. R. I. Thorpe and R, Mulligan,Geological Survey of Canada, Drs. J. A.Mandarino and F. J. Wicks, Royal OntarioMuseu,m, Dr. E. W. Nuffield, University ofToronto, W. L. Roberts, South Dakota Schoolof Mines and Teshnology, and Dr. J. S. White,Smithsonian Institution. The manuscript bene:fited from critical reading by Dr. J. L. Jambor,CANMET. One of us (S.A.K.) received $up-port from the National Research Council ofCanada in the form of a postdoctoral fellow-ship tenable at CANMET.

Rnnr,nsNcrs

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135TIN SULFIDE MINERALS

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Received July 1978: revised manuscript acceptedSeptember 1978.