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Home , Bismuthinite, Crystallography, Crystal chemistry, Tellurobismuthite, Tetradymite

Ameican Mineralogisl, Volume 76, pages 257-265, 1991

Crystal and of some in the

Ptrrn Berr-rss Department of and ,The University of Calgary,Alberta T2N lN4, Canada

AssrRAcr Selen- is a mixture of the minerals and tellurium. The in stibarsenare ordered(completely or partially) so that the correct chemical formula is AsSb. Matildite AgBiSr, bohdanowicziteAgBiSer, and volynskite AgBiTer, show atomic ordering in P3ml with unit-cell dimensions similar to those of tsumoite, BiTe. The S and Te atoms are apparently disorderedin ingodite to yield the chemical formula Bi(S,Te) and in sulphotsumoite to yield the chemical formula Bi(Te,S). The unnamed of Aksenov et al. (1968) seemsto be tellurian tsumoite, (BiorrTeoor)Te.The synthetic com- position of Godovnikov et al. (1966) is equivalent to bismuthian tsumoite, Bi(Teo"Bio,'). Platynite is possibly plumbian sulfurian nevskite, (Bio65oPbo 34s)(Seo.urrSo ror). Kawazulite, BirSeTer,is isostructural with tetradymite. Csiklovaite is a mixture of te- tradymite and bismuthinite. The chemical formula of skippenite is probably Bir(Se,Te,S)r, like that oftellurian paraguanajuatite.The Se and S are disordered in laitakarite to yield the chemical formula Bio(Se,S)..As S and Te ordering was not observed in josEite or josgite-B,there is possiblya completesolid solution seriesfrom tellurian ikunolite, Bio(S,Te)r, to sulfurian pilsenite, Bio(Te,S)r.The unnamed mineral of Yingchen (1986) is apparently tellurian ikunolite. Rucklidgeite, BirTeo, has an antipilsenite, BioTer, structure type. The unnamed mineral of Haraflczyk (1978) is rucklidgeite.

INrnonucrroN in order to investigate some of the problems associated group. The principal objectiveswere The narrow definition of the tetradymite group was with minerals in this given by Strunz (1970) to include only Bir(S * Se + Te), as follows: minerals. These hexagonalor trigonal minerals have an l. To obtain X-ray powder- data for minerals approximately cubic closest-packedlayer struc- where no published data exist, or discredit the mineral ture (Pauling, 1975) in which the five planes within the (e.g.,selen-tellurian, csiklovaite). tetradymite layer are Te-Bi-S-Bi-Te. The axis [0001] of 2. To use published X-ray powder-diffraction data to de- the hexagonal cell correspondsto [1 1l] of the approxi- termine if the crystal structuresare ordered, partially mately cubic closest-packed , where the ordered, or disordered in order to ascertain the correct planes are stackedperpendicular to [11]. The relation- chemical formula (e.g.,stibarsen, volynskite, ingodite, ship between different ratios of Bi:(S + Se + Te) and sulphotsumoite, kawazulite, skippenite, laitakarite, Te:S with respect to the d-value with the strongestcor- jos6ite,jos6ite-B). responding intensity in X-ray diffraction patterns was 3. To reindex the published X-ray powder-diffraction data discussedby Spiridonov (1981). The definition ofthe te- and obtain refined unit-cell dimensions (e.g., matil- tradymite mineral group was widened later by Bayliss et dite, bohdanowiczite). al. (1986) to include as essentialthose chemical elements 4. To identifi unnamed minerals, incorrectly named from group Va (As, Sb, and Bi) and group VIa (S, Se,and minerals, and synthetic phaseswithin the tetradymite Te) to produce eight subgroups each with a different num- group. ber ofplanes in the basic layer repeat unit layer. Table I 5. To review the literature and ascertain the status of lists minerals within the tetradymite group, which may platynite. be subdivided on the basis of the number of approxi- mately cubic closest-packedplanes in the layered repeat Mrrrroos unit, where each plane contains one or In the approximately cubic closest-packedlayered me- a random distribution of two or more chemical elements. tallic minerals, the number of possible crystal structure Differencesin atomic size and electronegativityallow or- types is limited. All of the crystal structure types have dered crystal structures at low temperature, but there are atoms with -fixed values of coordinates x and disordered crystal structures with extensive solution y, whereasthe coordinate z may or may not have a fixed at high temperature. value. Some atoms may have ordered, partially ordered, The purpose of this paper is to compare and contrast or disordereddistributions. From thesepossible ordered, the various mineral specieswithin the tetradymite group partially ordered, or disordered crystal structure types with 0003-004x/9l /0 l 024257$02.00 257 258 BAYLISS: TETRADYMITE GROUP

TABLE1. Subgroups within the tetradymite group TABLE2. Unit-celldimensions obtained by least-squaresrefine- ment No. of Space Subgroup Powder planes group name Chemicalformula diffrac_ 1 nel Te selenium Se tion file tellurium Te or spect- 2 R3m As antimony sb Chemicalformula men no. a (A) c (A) arsenic As stibarsen AsSb 31-80 4.025s(11)10.837(9) bismuth Bi matildite AgBiS, 24-10314.0662(21) 18.958(17) stibarsen AsSb bohdanowiczite AgBiSe, 29-14414.2049(14) 19.650(11) frm1 tsumoite tsumoite BiTe volynskite AgBiTe, 18-11734.468(7) 20.7s(5) sulphotsumoite Bifie,S) ingodite Bi(So*Teo*Seoo,)37 4.2477(24)23.075(221 nevskite BiSe ingodite Bi(Teo,.So*) platynite 77 4.246(3) 23.26(3) (Bi,Pb[Se,S)(?) sulphotsumoite Bi(Teo6?50s) 38-442 4.304s(18) 23.47q141 ingodite B(S,Te) tsumoite (Bio 22-117 4.36413) 24.32(4) bohdanowiczite 56Teon2)Te AgBiSe, tsumoite Bi(feo 19-176 4.4sq3) 23.90(3) malildite ?sBio25) AgBiS, laitakarite Bi.(Seo",Soj. 1+220 4.2239(14)39.94(3) volynskite AgBiTe, ikunolite Bi3 4.258(3) 39.s4(4) frm tetradymite tellurantimony ss2oTels Sb2Te3 Bi3 22-364 4.2402(12)39.77411s1 iosEite es2seorTer o BiJe3 joseite Bi415, 12-735 4.241s(10)39.76906) paraguanaiuatite Bi2Se3 eTe,o joseitsB Bi43s' 'so Je' o 9-43s 4.3i'26(25)40.92(5) skippenite Bi,(Se,Te). rucklidgeite (Bi,Pb)sTe4 29-234 4.4180(13)41.513(15) tetradymite Bi,sTe, rucklidgeite BeJe4 4.389(16) 42.0(3s) kawazulite BirSeTe. protoioseite BissTe1sS16 4.3386(11)57.804{18) F3n joseite ikunolite Bils3 aleksite Bi2PbSrTe2 29-765 4.2423(25)79.73(5) jos6ite Bi.(S,Te)o laitakarite Bi.(Se,Te)3 pilsenite BilTe3 ioseite-B Bi/Te,S)g poubaite (Bi,Pb)3(Se,Te)r rucklidgeite BiJei been found naturally, even though at least five Se-Te 9 frm1 protojosaite protojoseite Bis(fe,S)4(?) phases have been synthesized.The crystal structure of 14(?) P3m1 aleksite aleksite BirPbSrTe,(?) 2O(?) ? hedleyite hedleyite Bi?Tes(?) both minerals (i.e., selenium, tellurium) in spacegroup P3,21 has Se or Te in 3(a) at (x,O,Yt)with x about 0.25. A complete solid-solution seriesoccurs at moderate tem- peratures(200-450 "C) from selenium(a: 4.37,c: 4-95 values for z estimated from similar crystal structures, A, PDF 6-362)ro tellurium (a: 4.46, c : 5.93 A, pof X-ray powder-diffraction patterns were calculated with 4-554) without superstructure reflections (Lanyon and the program of Smith (Pennsylvania State University). Hockings, 1966).Appreciable segregationoccurs if a melt The number of crystal-structure models may vary from is not cooled instantaneously.A phasewith both Se and two for a two-plane structure type such as stibarsen,to Te in fixed proportions would require a crystal structure ten for a seven-plane structur€ type such as jos€ite. type different from that of selenium and tellurium. As yet The calculated intensities for each possible crystal- such a phasehas not been synthesized,and it is unlikely structure model were compared to the observedintensi- to occur becauseof the difference in atomic radii of Se ties of the published X-ray powder-diffraction data. The and Te. observed X-ray powder-diffraction data were reindexed, Enquiries for selen-tellurium at eight large mineralog- and improved unit-cell dimensions were obtained by least- ical museumsrevealed only one specimen,NMNH Rl86 squaresrefinement of unit-cell parameters.If the calcu- (Smithsonian Museum). This specimen, from the only lated intensities are similar to the visually estimated ob- known locality, Honduras, was initially examined with a served intensities in the literature, then a qualitative Kevex solid-state detector on an SEM. Distinct grains conclusion may be made on the order-disorder to yield were identified as , barite, selenium,tellurium, and probable chemical formula, structure type, and unit-cell selen-tellurium. The mineral assemblageof the specimen dimensions. The calculated X-ray powder-diftaction data is identical to that describedby Dana and Wells (1390), of the crystal-structuremodels that give the best possible so that this specimen probably comes from the type lo- fit to the observedX-ray powder-diffraction data are giv- cality. The sp€cimenitself has not been establishedcon- en in the tables in order to show the goodness-of-fi1. clusively to be a type specimen; however, none of the X-ray powder-diffraction patterns of the very small type specimenappears Io exist. specimens available were obtained with a 114.6 mm The grains were too fine for mounting in a polished Gandolfi camera (Fe radiation; Mn filter). The intensities block for -probeanalysis. An X-ray powder-dif- were measuredwith an automated densitometer. fraction photograph taken of the fine grains containing both Se and Te was identified as a mixture of selenium Tn suscnoup and tellurium. The unit-cell dimensions of selenium and Selen-tellurium, (Se,Te) with Se:Te : 2:3, was origi- tellurium are similar to those of pure Se and Te, so that nally describedfrom the El Plomo silver mine, Ojojoma negligible substitution of Te occurs in selenium and neg- District, Tegucigalpa, Honduras by Dana and Wells ligible substitution of Se occurs in tellurium. (1890). Only one phaseconsisting of both Se and Te has Therefore, selen-tellurium may be discredited and is BAYLISS: TETRADYMITE GROUP 2s9

TABLE3. X-ray powderdiffraction data for stibarsen TABI-E4. X-ray powder-diffractiondata for volynskite

Ie Volynskite Tellurobismuthite

,e Order Disorder /d l* ,e

003 30 6 0 6.28 D 101 10 't5 0 4.95 10 012 100 t00 1oot 2.78 101 102 104 60 35 39 3.60 012 52 110 70 28 32 3.36 013 52 015 10 c 0 3.21 80 3.222 006 10 6 7 3.09 104 100 100 113 10 I 0 2.U 105 10 1 021 5 4 0 2.3i] 107 30 1 2.376 25 202 40 13 17 2.28 10 o24 20 8 11 2.21 110 50 40 2192 25 107 10 2 0 2.15 018 30 36 116 20 10 15 1.98 019 10 1 122 40 8 13 1.82 o24 30 21 1.8't2 I 018 5 4 o 1.73 00.12 106 009 10 1 0 1.61 119 20 0.2 1.611 6 214 10 6 10 1.55 208 20 13 300 10 3 4 1.490 I 125 5 3 0 1.45 211 10 0.3 03it 5 3 0 1.42 213 51 208 5 2 3 1.41 214 20 18 10.10 10 2 3 1.37 11.12 10 16 220 20 2 3 1.30 300 10 7 036 5 3 o 1.27 128 10 13 312 20 3 6 't.29 10.16 106 02.10 5 2 3 134 10 3 6 315 10 3 0 o42 10 2 3 21.10 10 4 6 l2 observedreflections have 1 : 0 with a disorderedcrys- 11.12 5 4 7 tal-structure model, but thesereflections have 1 > 0 with 10.13 5 2 0 045 5 2 0 a completely ordered crystal structure, stibarsen is con- cluded to be ordered and have the chemical formula AsSb. The visually estimated observed intensity data are not sufficiently accurate to exclude partial disorder of As and shown to be a mixture of selenium and tellurium. A pro- sb. posal to discredit selen-tellurium as a mixture has been approved by the International Mineralogical Association Tsuuorrn suBGRouP Commission on New Minerals and Mineral Names (IMA Matildite, AgBiSr, as described by Geller and Wernick cNMMr{). (1959), shows ordering in space group P3ml compared to tsumoite, BiTe, which has been describedby Yamana As suncnoup et al. (1979). The refined unit-cell dimensions based on Trzebiatowski and Bryjak (1938) show a continuous the matildite X-ray diffraction data (PDF 24-1031) from between As and Sb at 400 "C; however, a Harris and Thorpe (1969) are given in Table2. The value minimum melting point in a continuous solid solution is of Frn (Smith and Snyder, 1979) increases from characteristic of a transformation in the solid state. As 2(0.060,242)to 5(0.070,84),where Fiv: overall value of the unit-cell dimensions of stibarsen (PDF 3l-80) are F,( lA, | ,NN) with i/ as the number of observed reflec- midway between those of As (PDF 5-632) and Sb (PDF tions. The increase in .F, reflects a significant change in 35-732), the chemical composition should be approxi- unit-cell dimensions during refinement. mately midway between As and Sb. The specimen for Bohdanowiczite, AgBiSer, as described by Geller and PDF 3l-80 contained arsenic intergrown with stibarsen, Wernick (1959) shows ordering in space group P.3ml which sr ggeststhat stibarsenmay exsolve from parado- compared to tsumoite, BiTe. The refined unit-cell di- crasite, AsSb, (Ironard et al., 197l). Stibarsen rather than mensions based on the X-ray diffraction data fsr boh- allemontite is the correct mineral speciesname (Hey, danowiczite (PDF 29-1441) from Pringle and Thorpe 1982). (1980) are given in Table 2. The value of .Froincreases StibarsenX-ray powder-diffraction data from PDF 3l- from 4(0.045,162) to 10(0.051,59). 80 were refined in spacegroup R3m to produce the unit- Volynskite, AgBiTer, was described by Bezsrnertnaya cell dimensions given in Table 2. X-ray powder-diftac- and Soboleva(1965). The XRD data for volynskite (PDF tion patterns were calculated both for an ordered AsSb I 8- I I 73) were indexed using spacegroup P3zel; the unit- crystal structure model with As at 0,0,0 and Sb at0,0,Vz, cell dimensions in Table 2 correspond to a value of Fro and for a disorderedcrystal-structure model (As,Sb).The of2(0. I 50,78).Reflections that could not be indexed were calculated intensities are compared to the visually esti- largely those of tellurobismuthite, BirTer, as shown in mated observedintensities of PDF 3l-80 in Table 3. As Table 4 (PDF 15-863),in addition to weak reflectionsfor 260 BAYLISS: TETRADYMITE GROUP

TmLE5. Atomiccoordinates of volynskite,space group PBml TABLE7. X-ray powder4iffraction data for ingodite, sulphotsu- moite. and tsumoite Atom Equipoint Ingodite Ag 1(b) 0 0 V2 Sulpho- (Bio*- Bi(Teo7t Ag 2(d) V3 ry3 +5 /e tsumoite Teo4)Te Bio*) Bi 1(a) 0 0 0 Bi 2(d) l/s +5 0.163 /-" ,* l*o ,* l* ,* /*. Te 2(c) 0 0 V4 005 20 30 12 303 204 Te 2(d) 1/g %. 0.417 't2 't2 Te 2(d) t/s +5 0.917 101 20 202 0.3 102 102 25 1 103 106 108 007 25 0.1 104 100 100 100 100 100 100 100 100 100 which d : 6.28 ard2.28 A. An X-ray powder-diffraction 105 <10 1 3 pattern was calculated for an ordered crystal-structure of <10 10 volynskite, 106 <10 10 1 203 25 1 as in the casesof matildite and bohdanowicz- 108 50 60 39 60 37 38 43 70 38 ite; atomic coordinates are given in Table 5. The calcu- 00.11 25 1 lated intensities in Table 4 are similar to the visually 110 50 34 50 35 38 33 80 37 111 104 estimatedobserved intensities of PDF l8-1173, indicat- 10.10 102 ing an ordered crystal structure. 00.12, Ingodite, 115 30 40 14 308 BirSTe, was describedby Zav'yalov and Be- 10.11 <10 10 1 20 1 gizov (1981) as having spacegroup P3*1. The rangeof 117 <10 10 2 12 chemical analysesgiven by Zav'yalov et al. (1984) 204 20 30 18 40 18 25 18 40 19 206 10 1 varies from Bir 'oPboo2S, ,rSeo orTeo ,u to Bi, ,.Pbo,oSo nr- 119 50101 Te, or. The refined unit-cell dimensions of their specimen 10.13 <10 10 4 104 37 (BirooPboorS,,rSeoorT€oru)and specimen77 10 11.10 10 0.1 10 1 (Bi,.nrSonoTe, ,o) are given in Table 2. An ordered crystal- 208 20 20 11 30 11 50 12 50 12 structure model of BirSTe with atomic coordinates sim- 10.14 10 1 ilar to those of matildite, AgBiTer, produced 209 102 a calculated 11.12 10 30 15 30 13 38 18 70 't4 X-ray powder-diffraction pattern significantly different 211 10102 10 0.3 from the observed X-ray powder-diffraction pattern of 213 10101 214 20 30 15 40 15 25 15 40 16 ingodite. A crystal-structuremodel of Bi(S,Te),similar to 10.16 405 that of tsumoite, with z atomic coordinate adjusted for 11.14 20301 10 1 the smaller S atom has atomic coordinatesgiven in Table 20.13 10102 10 1 218 30 20 11 30 10 25 11 30 11 6. The intensities of the calculatedX-ray powder-diffrac- 300 30205 206 106 tion pattern given in Table 7 are similar to the visually Notej The numbers37 and 77 are specimennumbers from Zav'yalov €t estimated observed X-ray powder-diffraction intensities al. (1984). of ingodite. Therefore, the chemical formula of ingodite (specimen 37) is inferred to be Bi(S,Te), whereas speci- men 77 is inferred to be tsumoite, Bi(Te,S). The visually estimated observedintensity data are not sufficiently ac- mated observed X-ray powder-diffraction intensities of curate to exclude partial ordering ofS, Se, and Te. sulphotsumoite. Therefore, the chemical formula of sul- Sulphotsumoite, BirTerS, was originally described by photsumoite is inferred to be Bi(Te,S). The visually es- Zav'yalov and Begizov (1982) as having space group timated observed intensity data are not sufrciently ac- P3ml. The refined unit-cell dimensions of sulphotsu- curate to exclude partial ordering ofS and Te. moite (PDF 38-442) are given in Table 2. Disordered Te The unnamed mineral of Aksenov et al. (1968) has Bi: : and S in a crystal-structuremodel similar to that of tsu- Te 2:5. The X-ray powder-diftaction data (PDF 22- moite, with formula Bi(TeourSorr)have atomic coordi- I 17) were indexed assuming space group P-3m1, as in nates similar to Te * S of ingodite as given in Table 6. tsumoite. and the refined unit-cell dimensions are listed The intensities of the calculatedX-ray powder-diffraction in Table 2. Crystal-structure models were constructed with pattern given in Table 7 are similar to the visually esti- both Bi and Te ordered and disordered in the tsumoite structure type. Many of the calculated X-ray powder-dif- fraction intensities are similar to the visually estimated TABLE6. Atomiccoordinates of ingodite,space group P3m1 observed intensities in Table 7; however, some signifi- cantly higher observed intensities are probably due to Equipoint incorrect atomic coordinates. Although the exact nature Bi 2(c) 0 0 0.124 of the Bi-Te order-disorder cannot be established,the l/a Bi 2(d) +5 0.291 (Bio Bi 2(d) +5 Yz 0.459 mineral seemsto be a tellurian tsumoite, rrTeoor)Te, s+Te 2(c) 0 0 0.362 even though the chemical composition is far removed s+Te 2(dl h ry3 0.056 from BiTe. s+Te 2(d) % v3 o.2'11 A synthetic phasewith Bi:Te : 5:3 was cooled from a BAYLISS:TETRADYMITE GROUP 261 molten solution at700-270 "C at 5'C/h by Godovnikov Tlau 8. X-ray powder-diffractiondata of kawazulite and skip- et al. (1966). The X-ray powder-diffracriondata (pDF lg- penite 176) were indexed by those authors on a unit cell ofthe Skippenite hedleyite type; however, the large differencebetween the observedand calculatedd-values indicates that the unit- Kawazulite L"" cell dimensions are incorrect. The data were reindexed Dis- Or- /*" I* /* ordered dered on a structure of the tsumoite type and the refined unit- cell dimensions are given in Table 2. A crystal-structure 003 10 3 50 16 33 model 006 40 10 60 11 7 for Bi(Teo.rrBiorr) was inferred having coordinates 101 30960 10 8 similar to those of tsumoite, BiTe. The intensities of the 009, 104 10420 65 calculated X-ray powder-diffraction pattern given in Ta- 015 100 100 100 100 100 107 102 00 ble 7 are similar to the visually estimated observedX-ray 018 20310 710 powder-diffraction intensities of the synthetic (pDF 00.12 10 1 00 19-176). Therefore, the composition phase 10.10 50 38 70 35 36 of the synthetic 01.11 10550 53 is equivalent to bismuthian tsumoite, Bi(TeorrBio rr). 110 50 34 80 32 32 Platynite from Fahlun, Sweden, was originally de- 00.15 10630 56 scribed 116, 10.13 10930 11 10 by Fink in l9l0 (Palacheet al., 1944).Although 01.14,021 10 2 208 22 the specimen has been lost, Strunz (1963) quotes from a 205 20 18 40 16 16 1933 private communication from F. E. Wickman who 10.16,00.18,208 10530 cc 11.12 61 00 statesthat the unit cell is hexagonalwith dimensions c : 02.10 10 11 40 99 8.49 and c: 20.80 A; however,the structureis not known. 01.17 10 1 00 As this c dimension suggests 11.15 10 13 508 10 10 a tsumoite-type structure, 01.20 430 33 the original analysis may be recalculated without chal- 125 10 14 408 11 11 copyrite and insolubles, and expressedas (BiouroPboror)- 02.16,1 1 .18 10520 55 21.10 440 77 (SeourrSoro*).Therefore, platynite may be plumbian sul- furian nevskite. Berry and Thompson (1962) stated that platynite is similar to selenjos€ite.Ramdohr (1980) gavedata for four powder-diftaction intensities of kawazulite (PDF 29-248) X-ray powder-diffraction reflections for platynite, but he listed in Table 8. The visually estimated observedinten- could not remember (Ramdohr, personal communica- sity data are not sufficiently accurate to exclude partial tion, 1983) the locality of his specimen and was unable ordering ofSe and Te. to supply either the original X-ray film or a specimen. Csiklovaite was introduced by Koch (1948) for a min- The composition of platynite by Nikitin et al. (1989) is eral from Csiklova, Rumania, with the chemical formula similar to that of poubaite; however, the X-ray powder BirSrTe. The validity of the mineral has been questioned data could not be indexed on a cell for any mineral of by somecompilers; e.9., Fleischer (1987). To obtain X-ray the tetradymite group. Therefore, platynite remains a powder-diffraction data of csiklovaite, eight specimens questionablespecies. consistingof severalsmall grains and two small vials were obtained from G. Grasselly,who supplied the type spec- Tnrn-lnravrrrE suBcRoup imens used by the late Sandor Koch to describe csiklo- Tetradymite, BirSTer, has been synthesizedby Glatz vaite. (1967), Evdokimenko and Tsypin (1971), and Abrikosov In reflected light, three areas with distinctly different and Beglaryan (1973). The compositional limits of te- colors can be seenas follows: (l) creamy yellow, (2) light tradymite have been shown to be BirSTer-BirS,rTe,.rAs blue-gray, and (3) darker blue-gray. This description determined by Kuznetsov and Kanishcheva (1970) with matches that of Koch (1948). The eight specimenswere internally consistent X-ray powder-diffraction data. Pau- analyzed,for As, Bi, Pb, S, Se, and Te with an electron ling (1975) has explained why the substitution of Te by microprobe under operatingconditions of 20 kV, 15 mA, S increasesthe chemical stability. 3 pm beam size, and 5 s count times. Grains from the Kawazulite, BirSeTer,was originally describedby Kato vials were identified by X-ray powder-diffraction as a (1970) as the Se analogue of tetradymite. The crystal mixture of tetradymite, BirS, ,Seo,Te,, (creamy yellow), structure of synthetic BirSeTe, was solved by Bland and galenobismutite (light blue-gray), and bismuthinite (dark Basinski(1961), and confirmed by Nakajima (1963),in blue-gray). spacegroup R3m (166) with the atomic coordinates of Bismuthinite and galenobismutite occur as lamellar and Se0,0,0, Te 0,0,0.211,and Bi 0,0,0.396.As Sedoes not myrmekitic intergrowths within tetradymite. These fine- have a significantly greater radius than Te, there is the grained minerals are therefore difficult to separate. A possibility that the Se and Te may be disordered. The mixture of 60 wto/otetradymite @irSTer)and 40 wto/obis- calculatedintensities of an X-ray powder-diffraction pat- muthinite (BirS.) would approximately reproduce the tern of kawazulite with the ordered tetradymite structure chemical analysisof csiklovaite reported by Koch (1948). type are similar to the visually estimated observedX-ray No evidence has been found in studies of svnthetic 262 BAYLISS: TETRADYMITE GROUP phases(Glatz, 1967 ; Kuznetsov and Kanishcheva, 1970; coordinates of Bio(STer)were taken as Bi at 0,0,0.1447 Evdokimenko and Tsypin, 197l) to suggesta phasewith and 0,0,0.2842,and Sorr.Teouu,in 0,0,0 and 0,0,0.4260 a composition near that of csiklovaite. A phasewith the for spacegloup R3ru. Jos6itewith ordered S and Te has composition of csiklovaite does not exist among the syn- 006 strong, whereasjosdite-Bwith ordered S and Te has thetic phasesor type specimens.A proposal to discredit 003 strong. The calculatedintensities in Table 9 are sim- csiklovaite as a mixture has been approved by the IMA ilar to the visually estimatedobserved intensities ofjosEi- CNMMN. te (PDF 12-735) given by Peacock(l9al) and joseite-B Skippenite, BirSer(TeonSo ,), was describedby Johan et (PDF 9-435) as consistent with the disordered crystal al. (1987), and was inferred to be the Se analogueofcsik- structure types, Bio(S,Te),and Bio(Te,S)r. lovaite. The crystal structure determination of BirSerTe The original X-ray powder-diffraction photographs by Nakajima (1963) shows a partially disordered crystal (57.3 mm diameter Debye-Scherrer)of jos€ite by Berry structure with atomic coordinates for Se at 0,0,0, and Thompson (1962) were borrowed from the Royal (Seor,Teor)at 0,0,0.2115,and Bi at 0,0,0.3985in space Ontario Museum, and new X-ray powder-diffraction films group R3m, yielding a chemical formula similar to that were taken of specimens ROM Ml9602a (os€ite) and of kawazulite, BirSe(SeTe).X-ray powder-diffraction pat- ROM Ml9602b (os6ite-B).As neither 003 nor 006 was terns were calculated for a partially disordered crystal- observedin any ofthese photographsor reported in the structure model and an ordered crystal-structure model literature, the S and Te are inferred to be disordered. In with the atomic coordinatesTe 0,0,0, Se 0,0,0.212,and addition, a wide solid-solution rangebetween BioTe, (pil- Bi 0,0,0.396in spacegroup R3m. The calculatedX-ray senite)and BioS,(ikunolite) is suggestedby the chemical powder-diffraction intensities of both crystal-structure formulae in Table 2 and by so-called jos6ite-C models as given in Table 8 are similar to the estimated (Bio,S,,Teo,)from Godovikov et al. (1970) and josEite observedX-ray powder-diffraction intensities of Johan et from Minster et al. (1968). Therefore,jos6ite, Bio(S,Te)., al. (1987). The chemical formula of skippenite is proba- is inferred to have a chemical formula similar to that of bly either BirSe(Se,Te,S),or Bir(Se,Te,S)r,as is true for tellurian ikunolite, whereasjos€ite-B, Bio(Te,S)', is in- tellurian paraguanajuatite. ferred to have a chemical formula similar to that of sul- furian pilsenite. Josiirrn suBGRouP The unnamed mineral of Yingchen (1986) gave a Laitakarite, BioSSer,was described by Vorma (1960); chemicalanalysis with 8i75.42,Te 19.2,and S 6.65wto/0. however, Nakajima (1963) statedthat the Se and S could The X-ray powder-diffraction data were indexed in space be either ordered or disorderedwithin spacegroup R3n. group R3m as for ikunolite, and the refined unit-cell di- The refined unit-cell dimensions of laitakarite (PDF 14- mensions are given in Table 2. As 003 is not observed, 220) are given in Table 2. An X-ray powder-diffraction a disordered crystal structure is suggestedin which the pattern was calculated for a disordered crystal-structure chemical formula is (BirrTeor)(SroTe,.o);i.e., this phase having spacegroup R3m wirthatomic coordinatessimilar is tellurian ikunolite. to those of ikunolite, (BioSr;Kato, 1959) and pilsenite, Rucklidgeite [(Bi,Pb)rTeo]was originally described by (BioTer; Yamana el al., 1979). The SorrrSeo...,occupies Zav'yalov and Begizov (1977); however, the Pb does not sites with coordinates 0,0,0 and 0,0,0.426, whereas Bi appear to be essentialso that the end-member chemical occupiessites at 0,0,0.142and 0,0,0.287.A secondcal- formula is taken as (BirTeo). The unit-cell dimensions culated X-ray powder-diffraction pattern was calculated (PDF 29-234) were refined and are given in Table 2. An for an ordered model with the S atom at 0,0,0, and the X-ray powder-diffraction pattern was calculated using a two Se atoms at 0,0,0.426. The calculated data for both crystal-structuremodel similar to that for BioSe,of Sta- the ordered and disordered crystal-structure models, which sova (1968). The model is for spacegroup R3m, $iith Bi are given in Table 9, can be compared to the visually at 0,0,0 and0,0,0.429,and Te at 0,0,0.143and 0,0,0.286. estimated observed intensities (PDF 14-220) of Vorma The intensities of the calculatedX-ray powder-diffraction (1960). The calculated data of the disordered crystal- pattern given in Table 9 are similar to the visually ob- structure model are similar to the observed data (PDF served intensities of PDF 29-234 (Zav'yalov and Begi- 14-220), especially for 003 and 006, so that the correct zov,1977) and PDF 38-458 (Robertsand Harris, 1988). formula of laitakarite is Bio(So,S)r. The unnamed mineral (BirTeo)of Haraflczyk (1978) is Jos0itewas named after Safi Jos6,Minas Gerais, Brazil rucklidgeite. The unit-cell dimensions were refined as- by Kenngottin 1853(Palache etal.,1944). The chemical suming spacegroup R3m and are given in Table 2. formula and refined unit-cell dimensions for spacegroup Wehrlite was reexamined by Ozawa and Shimazaki R3m are given in Table 2. The data in PDF 9-435 (Li, (1982) and found to be a mixture of pilsenite, BioTer,and 1957) are for a typeJocality specimen.Calculated X-ray hessite,AgrTe. The discreditation was approved by the powder-diffraction patterns were produced for ordered IMA CNMMN. crystal-structuremodels for BioSTe,and BioSrTe,and dis- ordered crystal-structure models for Bio(TerS) and DrscussroN Bio(SrTe).The atomic coordinatesof Bio(S,Te)were taken The data ofBrown and Lewis (1962) show a wide range as Bi at 0,0,0.1433 and 0,0,0.2856,and SouurTeor'at of solid-solution of Bi and Te from 32 to 600/oTe. The 0,0,0 and 0,0,0.4260for spacegroup R3z. The atomic data of Godovnikov et al. (1966) for synthetic phases BAYLISS: TETRADYMITE GROUP 263

TABLE9. X-ray powder-diffractiondata of laitakarite,joseite, joseite-B, and rucklidgeite

Laitakarite l^. Jos€iteB Rucklidgeite

/*" Ordered Disordered L. /*t l* ,* le 003 38 4 3 I 006 3 30 2 1 c I 009 15 78 10 I 10 6 20 2 101 21 012 15 14 15 10 14 10 8 20 3 104 1 12 015,00.12 10 12 17 510 54 107 100 100 100 100 100 100 100 100 100 10.10 c 0.1 01.11 c 11 10 1 10 0.1 10.13 3 0.1 01.14 40 41 41 30 41 40 41 60 41 110 40 34 34 30 u 50 35 60 35 10.16 c 34 5 4 104 10 1 01.17 5 0.1 5 0.2 5 0.1 119 56 6 4 10 1 00.21 10 88 10 I 208 25 I 10.19,202 3 55 3 2 11.12,205 3 77 3 3 027 30 18 18 10 18 30 19 11.15 1 00 5 1 01.22 3 0.2 20.14 15 12 12 10 12 20 12 45 12 11.21 15 17 17 10 '17 10 17 35 18 02.16 1 1 1 217 15 15 15 10 15 20 15 30 15 10.28 3 7 7 3 0.1 7 10 7 12.14 I 11 11 10 11 10 11 25 12 300 1 D 5 3 c 10 6 21.16 5 1 1 10 2 309 '| 1 1 3 1 11.33 3B ,| 1 3 1 30.21 5 6 7 c 7

fvote.'The ws, vs, s, ms, m, mw, w, vw, and ww were taken as 100, 40, 30, 15, 10, 8, 5, 3, and 1, respectively

indicate a chemical formula of Bi, ,rTeorr, which extends dimensions,which are listed in Table 2, imply a structure the solid-solution rangefar beyond the ideal composition with a repeat unit ofnine closest-packedplanes. of BiTe. In contrast, the data of Brebrick (1968) for the Aleksite was originally described by Lipovetskii et al. Bi-Te system shovi a seriesof individual phaseswith 50- (1978). Their X-ray powder-diffraction data (PDF 29- 60 at.o/oTe after annealing for several days at 525 "C, 765) were indexed using space group P3ml, and the re- near the melting point. The identification of additional fined unit-cell dimensions are listed in Table 2. Hedley- phasesmay be due to the useof more sophisticatedX-ray ite, which was describedby Warren and Peacock(1945), techniqueshaving better resolution. was given the chemical formula BirTer; however, both The suggested disorder of S-Te in the natural series BirTe, and BirTe, are in better agreementwith the chem- BioSr-BioTe, (ikunolite-jos€ite-C-jos€ite-jos€ite-B-pil- ical analyses.The hexagonal subcell has refined dimen- senite) is difficult to explain. Most of the relatively few sionsa : 4.475(4)and c :5.367(3) A. observedspecimens have approximately integer ratios of Imamov and Semiletov (1971) consider that synthetic S:Te, which would favor an ordered structure at low tem- equivalents of the tetradymite-group minerals have an peratures. odd number of approximately cubic closest-packedplanes, The unnamed mineral of Gamyanin et al. (1980) is including the structures of BirSe, BirSer, BioSer,BioSer, BirTe. The X-ray powder-diffraction data were indexed BiuSer,BirSer, and Bi.Ser, which have all been synthe- with a hexagonal unit cell with a : 4.476(5) and c : sized and characterizedby Stasova(1968). The well-doc- 5.997(12) A; however, two reflections with d-values of umented minerals listed in Tables I and 2 basically fit 4.16 and 3.57 A could not be indexed either with this the relation involving an odd number of planeq however, unit cell or a supercell. the crystal structures of protojos6ite (9 atom planes), Imamov and Semiletov (1971) described BioSe,(c : aleksite(14 atom planes?),or hedleyite (20 atom planes?) 4.21,c : 51.54A;, SboTe,(a : 4.27,c : 53.79A), and have not been established(Table l). BioTe,(a : 4.41,c: 54.9A) ashaving space group P'3m1. The published X-ray powder-diffraction data were ob- Protojos6ite was redefined by 7,av'yalov and Begizov tained using a variety of kinds of equipment with differ- (1983). Their X-ray powder-diffraction data were in- ent degreesofprecision, and with intensities recorded on dexed using spacegroup P3ml, and the refined unit-cell films with different exposuresand estimated visually by 264 BAYLISS: TETRADYMITE GROUP different people. Published intensities tend to be very in- Garnyanin,G.N., Leskova N.V., Vyal'sov, L.N., and Iaputina, I.P. (1980) accurate,and are subject to preferred orientation in the Bismuth tellurides-Bi,Te and BiTe-in deposits of northeastern USSR. phasesunder discussionbecause of the common Zapiski VsesoyuznoyeMineralogichestogo Obshchestvo, 109, 230-235 {0001} (in Russian). perfect .Most investigatorsoverestimated the in- Geller, S., and Wernick, J.H. (1959) Ternary semiconductingcompounds tensity of weak reflections by using a scale of 5 to 100 with sodium chloride-like structure: AgSbSer, AgSbTer, AgDiSr, Ag- instead of 2 to 100. The intensities at the lower 20 angJes Biser. ,12, 46-54. often reflect the degreeoforder-disorder, whereasthe in- Glatz, A.C. (1967) The BirTe,-BirS, systemand the synthesisof the min- eral tetradymite. American Mineralogist, 52, 16l-170. tensities at the higher 20 anglesoften appear to be inde- Godovikov, A.A., Kochetkova, trLV., and Iawent'ev, Yu.G. (1970) Study pendent of such effects.In contrast, the majority of well- of the bisrnuth sulfotellurides of the Sokhondo deposit. Geology and refined crystal structures of the tetradymite group were Geophysics,1 1, 123-127 (in Russian). obtained with a carefully measuredseries of 0001 reflec- Godovnikov, A.A., Fedorova, Zh.N., and Bogdanova, V.I. (1966) An tions (nine to 36 of them). artifrcial sub-telluride of bismuth similar to hedleyite. Doklady f16a- demii Nauk SSSR,Earth ScienceSection, 169,142-144. The discrepanciesbetween the calculated intensities and Haraflczyk, C. (1978) Krakow Paleozoic telluride province. Przeglad Ge- the published observedintensities may be accountedfor ology,26, 337-343 (in Polish). by the poor accuracyof the visually estimated observed Harris, D.C., and Thorpe, R.I. (1969) New observations on matildite. reflections, the errors in estimated atomic coordinates, Canadian Mineralogist, 9, 65 5-662. ( possibility partial Hey, M.H. I 982) International Mineralogical Association: Commission the of order rather than either complete on New Minerals and Mineral Names. Mineralogical Magazirc, 46, order or disorder, or the possibility that further structural 513-514. complexities exist becauseof the hierarchy of subcells Imamov, P.M., and Semiletov, S.A. (1971) The crystal structure of the present in each X-ray powder-diffraction pattern. phasesin the systemsBi-Se, Bi-Te, and Sb-Te. Soviet PhysicsCrystal- Members of the tetradymite group present complex lography,I5,845-850. Johan,Z., Picot, P., and Ruhlmann, F. (1987) The ore of the problems, many of which remain unresolved due to in- Otish Mountains uranium deposit, Quebec: Skippenite, BirSerTe, and complete data. To confirm the structure type and the de- watkinsonite, CurPbBio(Se,S),, two new mineral species. Canadian gree of order-disorder in the mineral specieswithin the Mineralogist, 25, 625-638. tetradymite group, a series of crystal-structure determi- Kato, A. (1959) Ikunolite, a new bismuth mineral from the Ikuno mine, Mineralogical (Japan), 2, 397-4O7. nations must Japan. Journal be undertaken either by single-crystal or Kato, A. (1970) Introduction to Japaneseminerals. Geological Survey of Rietveld methods. Japan, 87-88 (not seen; extracted from American Mineralogist, 57, 1312, 1972). AcrNowr,nocMENTS Koch, S. (1948) Bismuth minerals in the Carpathian Basin.Acta Univer- sitatis Szegediensis,Acta Mineralogica, Petrographica,2, 17-23. Dr. E. Nickel, vice chairman of CNMMN, provided valuable advice. Kuznetsov, V.G., and Kanishcheva,A.S. (1970) X-ray investigation of Critical reviews were provided by J.E. Post, D.C- Harris and J.L. Jambor. alloys of the systemBirTer-BirS,. Inorganic Materials, 6, I I l3-l | 16. Financial assistance was provided by the National Scientific and Engi- Lanyon, H.P.D., and Hockings, E.F. (1966) The selenium-tellurium sys- neering Research Council of Canada. tem. PhysicsStatus Solidi, 17, Kl85-K186. RrrBnrNcns crrED konard, B.F., Mead, C.W., and Finney, J.J. (1971) Paradocrasite, SbdSb,As),,a new mineral. American Mineralogist, 56, 1127-1146. Abrikosov, N.IG., and Beglaryan, M.L. (1973) The system Bi,Se3-BirTerS- Li, A.F. (1957) Tellurium minerals in north-eastern Baikal region. Zapiski BirTe,. Inorganic Materials, 9, l36t-1363. Vsesoyuznoye Mineralogichestogo Obshchestvo, 86, 40-47 (in Rus- Aksenov,V.S., Kosyak,Ye.A., Mergenov,Sh.IC, and Rafikov, T.IC (1968) sian). A new Bi,Te,. Doklady Akademii Nauk SSSR,Earth Lipovetskii, A.G., Borodaev,Yu.S., andZav'yalov, E.N. (1978) Aleksite, ScienceSection, 181, I l3-l 15. PbBirTerSr, a new mineral. Zapiski Vsesoyuznoye Mineralogichestogo Bayliss,P., Erd, R.C., Mrose, M.E., Sabina,A.P., and Smith, D.K. (1986) Obshchestvo,107, 315-321 (in Russian). Mineral file, data book. JCPDS-Intemational Cen- Minster, E.F., Mymrin, V.A., and Isayeva, ICG. (1968) Jos€iteA from tre, Swarthmore, Pennsylvania. central Asia. Doklady Akadernii Nauk SSSR, Earth Section, Berry, L.G., and Thompson, R.M. (1962) X-ray powder data for ore 178,lt4-117. minerals: The Peacock atlas. Geological Society of America Memoir, Nakajima, S. (1963) The crystal structure ofBirTer-,Se.. Journal ofthe 85. Physicsand Chemistry of , 24, 47 9-485. Bezsmertnaya,M.S., and Soboleva,L.N. (1965) Volynskite, a new tellu- Nikitin, S.A., Anderson, E.8., and Petrova, N.B. (1989) New data on ride of bisrnuth and silver. Akademia Nauk SSSR, Eksperimental'no platynite and the lead isotope composition in associated selenides.Za- Metodicheskie Issledovaniia Rudnykh Mineralov Moscow, 129-l4l piski Vsesonrznoye Mineralogichestogo Obshchestvo, ll8, 22-28 (in (in Russian). Russian). Bland, J.A., and Basinski, S.J. (1961) The crystal structure of Bi,TerSe. Ozawa, T., and Shimazaki, H. (1982) Pilsenite redefned and wehrlite Canadian Joumal of Physics,39, 1040-1043. discredited. Proceedings of the Japan Academy, 58(B), 291-294. Brebrick, R.F. (1968) Characterizationof phasesin the 50-60 at. VoTe Palache,C., Berman, H., and Frondel, C. (1944) The systemof mineral- region of the Bi-Te system by X-ray powder diftaction pattems. Jour- ogy I (seventh edition). Wiley, New York. naf of Applied Crystallography,1, 241-246. Pauling, L. (1975) The formula, structure and chemical bonding ofte- Brown, A., and kwis, B. (1962) The systemsbismuth-tellurium and an- tradymite Bir"Te,,Sr,and the phaseBi,oTe,rSu. American Mineralogist, timony-tellurium and the synthesis ofthe minerals hedleyite and wehr- 60, 994-997. lite. Physicsand Chernistry ofSolids, 23,1597-1604. Peacock,M.A. (1941) On joseite, gdinlingite, oruetite. University Toron- Dana, E.S., and Wells, H.L. (1890) On some selenium and tellurium to Studies,Geology Series,46, 83-105. minerals from Honduras. American Journal of Science,40, 78-8 1. Pringle, C.J., and Thorpe, R.I. (1980) Bohdanowiczite,junoite and lai- Evdokimenko, L.T., and Tsypin, M.I. (197 l) How affectsthe prop- takarite from the Kidd Creek mine, Timmins, Ontario. Canadian Min- erties of BirTe,-basedalloys. Inorganic Materials, 7, 515-517. eralogist, 18, 353-360. Fleischer, M. (19E7) Glossary of mineral species. Mineralogical Record, Ramdohr, P. (1980) The ore minerals and their intergrowths. Pergamon Tucson, Arizona. Press, New York. BAYLISS: TETRADYMITE GROUP 265

Roberts,A.C., and Harris, D.C. (1988) Rucklidgeite. powder Diffraction Yamana, IC, Kihara, IC, and Matasumoto, T. (1979) Bismuth tellurides: File, 38, 458. BiTe and Bi4Ter.Acta Crystallographica,B35, 147-1 49. Smith, G.S., and Snyder, R.L. (1979) F": A criterion for rating powder Yingchen, R. (1986) Tellurobismuthinides from Pangushan,China. Geo- difftaction pattems and evaluating the reliability ofpowder-pattern in- chemistry (China), 5, 277-279. dexing. Journal of Applied Crystallography,12, 60-65. Zav'yalov, E.N., and Begizov, V.D. (1977) Rucklidgeite, @i,Pb),Te", a Spiridonov, E.M. (1981) The relationshipbetween chemical composition new mineral from Zod and Kochlar ore deposits. Zapiski Vseso- and certain X-ray propenies of bismuth tellurides. Mineralogicheskii yuznoye Mineralogichestogo Obshchestvo, 106, 62-68 (in Russian). Zhumal, 3(4), 76-80 (in Russian). Zav'yalov, E.N., and Begizov, V.D. (1981) The new bismuth mineral Stasova,M.M. (1968) Crystal structure of the bismuth selenide BioSe,. ingodite, BirTeS. Zapiski Vsesoyuznoye Mineralogichestogo Ob- Inorganic Materials, 4, 21. shchestvo,I 10, 594-600 (in Russian). Strunz, H. (l 963) Homiiotypie BirSe,-BirSe,-BirSe.-Bi.Se,usw. (platynit, Zav'yalov, E.N., and Begizov, V.D. (1982) Sulphotsumoite,Bi.Te,S, a Ikunolith, La.itakarit). Neues Jabrbuch fiir Mineralogie Monatsheft, 154- new bismuth mineral. Tapiski Vsesoyuznoye Mineralogichestogo Ob- 157. shchestvo,lll, 3 16-320 (in Russian). Strunz, H. (l 970) Mineralogische Tabellen. Akademische Verlagsgesell- Zav'yalov, E.N., and Begizov, V.D. (1983) New data on the constitution schaft, kipzig, Germany. and nomenclature of the sulfotellurides of bismuth of the josbite group. Trzebiatowski, W., and Bryjak, E. (1938) Rdntgenanalysedes Systems Zapiski VsesoyuznoyeMineralogichestogo Obshchestvo, I 12, 589-601 Arsen-Antimon. Zeitschrift fiir anorganische und allgemeine Chemie, (in Russian). 238,255-267. Zav'yalov, E.N., Begizov, V.D., and Tedchuk, V.Ya. (1984) Additional Vorma, A. (1960) Iaitakarite a new Bi-Se mineral. Bulletin de la Com- data on the chemical composition of ingodite. Zapiski Vsesoyuznoye mission g6ologiquede Finlande N:o, 188, l-10. MineralogichestogoObshchestvo, l 13, 3l-35 (in Russian). Wanen, H.V., and Peacock,M.A. (1945) Hedleyite, a new bismuth tel- luride from British Columbia, with notes on wehrlite and some bis- muth-tellurium alloys. University Toronto Studies,Geology Series, 49, Memrscnrp'r RrcErvEDMencr 19, 1990 55-69. Mexuscnrrr AccEprEDNowrvrsen 10, 1990