555 Booth Street, Ottawa, Ontario KIA OGl. E. KIRCHNER eNp W. PAAR ... pie est nette dans I'air et forte dans l,huile: la micro- duret6 VHN56 va de 201 I 244 ...
Canadian Mineralogist Vol. 16, pp. 127-l3O (1978)
FRIEDRICHITE, GurPbrBizSrs, A NEW MEMBEROF THE AIKINITE-BISMUTHINITE SERIES T. T. CHEN Mineral sciencesLaboratories, canada centre lor Mineral and Energy Technology, 555 Booth Street, Ottawa, Ontario KIA OGl E. KIRCHNER eNp W. PAAR Instbute of Mineralogy and Petrology, (lniversity ol Salzburg, Akademiest. 26, A-5020 Salzburg,Awtria
thinite series (Harris & Chen L976; Mumme et al. 1976). Each superstructure usually has a Friedrichite was found near the well-known small range of compositions and is characterized emerald deposit in tlle "Sedl" region, east of Habach by either Pbnm or Pb2tm space-groupsymmetry, V,alley, Salzburg, Austria. It occurs as aggregarcs of granular-shaped crystals, associated with chalco- and by an 4 parameter equivalent to a multiple pyrite, covellite, chlorite and mica, in vein-quartz of that of bismuthinite (or aikinite). The b and c parametersare similar to those in the bismuthiboulders. The mineral is a new superstructure of the aikinite-bismuthinite series: pb21m, a 3xll.2g, nite (or aikinite) cell. The cell dimensionsof the b 71.65, c 4.01A. The average composition, Cu 9.1, phasesin this series generally increase systemaPb 29.7, Bi 44.2, S 17.2 vttVo (totat tOO.Zj and the tically from those of bismuthinite to aikinite measured densitn 6.98 g/cms, suggest an ideal cell according to the amount of Cu and Pb substicontent CuloPbroBirnSre,between those of aikinite tuting for Bi. Cu and Pb atoms tend to distribute and hammarite. The mineral is creamy yellowishamong the maximum possiblenumber of bismuwhite in air, more pinkish in oil; bireflectance is thinite ribbons. Thus, the superstructureswith moderate and distinct, anisotropism is distinct and strong in air and in oil, respectively; micro-indenta_ compositions between krupkaite and bismuthition hardness VHNso is 201-244 (av.224). nite (e.9., gladite and pekoite) were found to consist entirely of bismuthinite (BLSo)and krupkaite (CuPbBisSu)ribbons (Kohatsu & Wuensch Sorvruanr 1973;Synedek& Hybler 1975; Mumme & Watts 1976), whereasthose with compositions befween D6couverteprds du gisementd,6meraude bien krupkaite and aikinite (e.9., hammarite and lindconnu de la r6gion SedL A l,est de la vallde de Ha_ bach, i Salzbourg en Autriche, la friedrichite se strdmite) consist entirely of krupkaite and aikiprdsente sous forme d'agr6gats de cristaux granunite (Cu,Pb,Bi:S) ribbons (Horiuchi & Wuensch laires associdsi la chalcopyrite, d la covelline-, i. la 1976; L977). Prior to the present study, during chlorite et au mica dans des blocs de quartz filonien. which the new member friedrichite (CuroPbroBiroCe min6ral est une nouvelle surstructure de la s6rie Sse)was discovered, only the five phases menaikinite-bismuthine: pb21m, a 3xlt.2g, b 11.65, c tioned above were known as intermediate mem!..Ote. Sa composition moyenne (Cu 9.1, pb 29.7, bers in this series. The mineral and name have \i.44.2, S l7.2Vo en poids; total, 100.2) et sa den- been approved by the Commission on New Minsit6 mesur6e (6.98) conduisent i Cu1jpb1sBi1aS3s, ce erals and Mineral Names, I.M.A. qui situe la friedrichite entre I'aikinite et t'trammuABsrRAcr
rite. La friedrichite est d'un blanc jaunitre cr6meux dans l'air, de teinte plus rositre dans I'huile; la bir6flectance est mod6r6e mais nette; l,anisotropie est nette dans I'air et forte dans l,huile: la microduret6 VHN56 va de 201 I 244 (moyenne 224). IntnooucrroN _ Hammarite (CuepbdiroSgu), lindstriimite (CurrPbrzBlrSoo), krupkaite (CuzpbrBieSrr), gladite (CuaPboBLoSsu)and pekoite (CurpbrBir^S*) are Known as superstructures in the aikinite-bismu_
GeNeRAr,DnscnrnoN The mineral was first found by two mineral collectors, E. Schnitzer and P. Ogris, and later by two of tle present authors (W. P. and E. K.) in a locality below the well-known emerald deposit of the "Sedf' region, at the east side of the Habach Valley, Salzburg, Austria. The mineral was found in the screes of a landslip. 1700m above sea level. The geology in this region is characterized by schists and gneisses,
L27
r28
THE CANADIAN I\{INERALOGIST
white. Anisotropism is distinct in air, strong in oil: from light creamy yellow or pinkish yellow to pink-grey or bluish $ey at 15' from, cro-ssed poGrs, froir gxey to dark with crossed polars. burned with effervescenceand ilNo, (t:t) darkened the surface with seconds. FeCls (20Vo) gave a light brown stain, whereas 1:1 HCI showed no effect. Reflectances were determined with a I*itz MPE microscope photometer using a calibrated silicon standard N2538.42, issued by IMA Commission on Ore Microscopy). The results measured on five grains in air gave as maJdmu.m and minimum values: at 47Onm,46.74LI (av. 44.2); 546 nrr., 46.24.I (av. 43.5); 589 nm, 45.8-39.9 (av. 43.0); 650 nm, 45.6'39'.9 (av. 42.9). Micro-indentation hardness values were determined with a Leitg Durimet hardness tester; the results on seven grains gave VIfNso= 201-244 (av.224). X-RIY CnYsrer- Dere Two crystals pre-analyzed with the electron probe were studied with a precession capeJa using MoKa radiation. The results showed the minJral to be a new superstructure of the aikiFrc. 1. Friedrichite showing alteration along cracks b series; 4 3xll.28-r}.02l' nite-bismuthinite to cerussite,hydrous (?) Cu-Bi sulfate and hy(Pb2m PbE* 4.01:t0.003A, c drous Bi carbonate-sulfate mineral. Matrix is 11.65:10.007, based on the structure of the aikinite-bismuthi' quanz. rtite series).The X-ray powder diffraction data ooHabach obtained using a 114.6 mm Gandolfi ,camera metamorphic rocks of the Paleozoic and Nlfiltered Cu radiation (L=1.5414A) from Series" (Frasl 1958). Nothing is known about these two crystals are compared with those obthe host rocks of friedrichite. Other sulfides, tained using a 114.6 mm Debye-Scherrercamera e.g., galenaocosalite, phases PbsBi:Se(heyrovin Table t. fhe data are very similar to those skyite?) and Pb..ssBir.ooSu.sa 0illianite type), were for aikinite. also found in the nearby screes. Friedrichite occurs as isolated crystals or, more commonly, as aggregates of granularCunurcel CovtPostrtor'r shapedto column-like crystals, 0.2 to more than Electron probe analyses were performed by 1.5 mm in size, embedded in head-sizedveinquartz boulders. Friedrichite shows alteration T.T.C. using an MAC model 400 probe, at (Fig. 1), most commonly along cracks, but also 25kV, with the following standards and. e!fsPbS randomly. Some friedrichite grains have been sion iines: synthetic Bi,Sg(Bitra), synthetic (CuKa,SKa)' The chalcostibite and completely altered to cerussite, a hydrous (?) @bLaI a process.q-Y11{ were data intensity X-ray carhydrous Cu-Bi sulfate and a wax-colored EMPADR from program modified -(Ruckiidge bonate-sulfate of Bi that shows a bismoclite-type computer -but& Casparrini 1969). Sb was X-ray powder diffraction pattern, whereas some VII not detected. Other elements for other grains show a relict core surrounded by analvzed the energy-dispersiveX-ray by detected not were Trace minerals. zones of these secondary analyzed. The.results grains were analyzer. Six amounts of chblcopyrite, covellite, chlorite and and are listed in 16 S atoms, to were calculated mica are also associated with friedrichite. gives Cu 9'1, analysis In polished section,the color of the mineral is Table 2. The average (totat pi too.z wt 7o), tz.z s and Bi 44.2 zg.l, in pinkish creamy yellowish-white in air, more this gives a Cue.o.Pbe.srBira.rsSgo; correspondingto oil. Bireflectance is moderate in air, distinct in with comparable g/ctns, 7:06 density calculited pink tint with a oil: from creamy yellowish-white the measured dinsity 6.98 g/cms obtained by to pinkisl grey-white or light bluish yellow-
FRIEDRICHITE,
'I. TABIE
NEW
MEMBER
OF THE AIKINITE-BISMUTHINITE
SERIBS
129
DrscusstoN X.RAYPOI4|DER DIFFRACTION DATAOF FRIEDRICHITE
Much has been reported on the crystal chemistry of phasesin the aikinite-bismuthinite series (e.9., Harris & Chen 1976; Mumme & Watts I n 8.10 0 1976). Tbe crystal chemical data of friedrichite 0 ,,tJ z 0 4.05 4.03 are closely related to those of aikinite (Pbnm, t 4.05 4 0 1 3.778 3.782 * 3.782 1 a Ll33A) and hammarite(Pbnm, a-3rll.2gA). 0 3.672 3.670 3.644 10 1 I 3 . 5 e 4I Using the data provided by Harris & Chen, the 3.580 3.584 10 9 1 0 3.578' ? tnt observed compositions of friedrichite (with 0 1 3.306 3.301 1 a I 3.170\ (Cu*Pb)/2Bi = 0.69-O.66)fatl between those J. IOU 10 3.161 10 o I I 3 . 1 4 7t E 2 I of aikinite ((Cu or Pb)/(Bi,Sb) - 0.85-0.71) 2.968 2.970 1 o I 2.850 2.850 5 2.850 and hammarite ((Cu or Pb)/Bi - 0.60-0.55). 12. n 0 2.820 t e1E v 0 1 2.743\ The proposed ideal formutragives a (Cu or Pb)/ 2.742 2.741 12, 1 . 0 z.tqtl Bi ratio of 0.71, which overlaps the range of 1 1 2.670 ?.67? a.oIc 4 0 2.588 ) qa7 2 . 5 9 0 aikinite. There may be no compositional gap , q?q 12. 0 2.539 .. IJJ between the aikinite and friedrichite solid solu1 2 . 5 0 0| 2,484 2,495 1 2.482t tion fields; as an alternative, the.substitution of ) 1EA 1 a .Jal 0 4 0 Bi by Sb may affect the stability fields of the 2.303 2.303 1 2.302 1 2 . 1 . 1 ?.263 2.262 1 2.?64 phases in the aikinite-bismuthinite series. o 4 1 2.!74 2.768 t 181 o 6 n Mumme & Watts suggesteda generalformula, a 2.155 12. 1 2.r45 2.141 a 2.146 Cu,PbJirs-.Sre, to represent the ideal composi15. 0 *.104 2.098 0 0 2.005 2.005 tions' of some of the members in this series: 1 ?.0tL 5 1 II . .99: I l=0 for bismuthinite, 1 for pekoite, 2 for gladite, !2. 1 YUJ / 1 070 1.981 E 0 r .g e r ) 3 for krupkaite, 4 for hammarite, and 6 for aiki0 A 0 1.942\ 1.940 1 nite. Nothing was known for r=5. Lindstrtimite 1.943 15.1 . I 1.939J 1q 0 . 0 1.880 1.879 (CuraPbr:BizeSao, 1.884 1 a d iXLL,ZA) is the only 12. 1 1.808 1.806 1 1.805 I known member which 2 does not satisfy an inte1.760 1 1 E a 1.760 ger x for this formula. The new mineral, friedC u K q - r a d l a t i o( n l - " t . s q r d ) ; ( l ) c a l c u l a t e dr r o ma - g g , 8 4 l richite, correspondsto the phase with .r=5. (?).ri4.6ffieanoorii ia'"ii,-rrri-iuren !,"^ll.:99, 9^: 1:914; a!.LANmLti.(J,| il4.6nm Debye_Scherrercamera, fllm taken at The crystal structures of the seven phases untv. salzburg. There is no explanation for differences previously known in this series, including aikiGandot fi and oebye_lcherier"fiiirr-i.r-l ljbii.a f( :l:"r o c u , r el!. ftectlons. nite and bismuthinite, have been su.mmarized Berman balance and toluene. The small variation by Horiuchi & Wuensch (1977). Since the idealin compositions possibly indicates a narrow ized cell content of each superstructure in this range of solid solution, usually found in the series can be defined by the general formula members of the aikinite-bismuthinite series.The Cu"Pb"Bie,J& (x is an integer in this case), structural cell formula for phases of the aiki- the ratio of the structural ribbons (i.e., aikinite krupkaite (Cu'PbBisSo),and bismunite-bismuthinite series in general can be repre- (CuzPb"BiaSo), thinite @iaSe)ribbons) for each superstructure s_ent9dby CuJb"Bi8,-"$s,, where z represints the integer multiple factor for the a parameter of thus can be derived directly from the idealized the superstrusturesin terms of thaf of the aiki- cell content, on the basis that all the superstrucnite cell. The z value is 3 for friedrichite. The tures with compositions between flsmulhinifs compositions observed (Table 2) thus suggestan and krupkaite would consist entirely of bismuthinite and krupkaite ribbons, whereasthose with ideal structural cell formula CuropbroBiiosgfor compositions between krupkaite and aikinite this mineral. consist entirely of krupkaite and aikinite ribbons. TABTE2. ELECTROI{ PROBE ANALYSES OFFRIEDRICHITE Only one combination for the structural ribbons is found for each superstructureoi,e., aikinite l,,leight percent Atonic prcportions (5=36) No. Cu PbBiS ribbons (aikinite)i 1 aikinile;2 krupkaite (hamTotal Cu Pb Bi s marite); 1 aikinite:4 krupkaite (indstriimite); 1 8 . 8 29.6 44.5 1 7. 4 1 0 0 . 3 9 . 1 9 9 . 4 8 t 4 . 1 3 3 6 krupkaite ribbons (krupkaite); 2 krupkaite:l 2 8 , 9 29.6 44.1 1 7 . 5 100.l 9.24 9.42 13.92 36 9 . 4 29.5 44.0 t 7. 0 bismuthinite Gladite); 1 krupkaite:2 bismuthi99.9 10.04 9.67 14.30 36 at 29.7 44.1 t7 . 0 100.0 9.83 9.73 14.33 36 nite (pekoite); and bismuthinite ribbons (bis9 . 0 29.9 44.2 t7 . l 100.2 9.s6 9.74 14.28 36 muthinite). The ratios (m:n, where rn*n-z) 9 . 1 29,6 44.0 9.61 9.59 14.13 36 99.9 derived are the same as tlose obtained by crystal structure analysis (see Horiuchi & Wuensch 1,977). The ratio derived for friedlt
h
I
dca1c1
d2 "meas
I.rt
d,neas3I est 8.10 1 5.79 I
J
I
J
130
THE
CANADIAN
MINERALOGIST
to Professor K. Keil (Inst. Meteoritics, Univ. richite is 2 aikinite: I krupkaite ribbon. The present finding of friedrichite perhaps New Mexico, Albuquerque) for the use of his implies that more new phases with structures facilities. consisting of combinations of bismuthinite and krupkaite ribbons or krupkaite and aikinite ribREFERENcES bons in ratios other than 1:2 and 2:1 exist in (1958): FRASL, G. Zur Seriengliederung der Schienature. Lindstrdmite, consisting of aikinite and ferhiille in den mittleren Hohen Tauern. lahrb. krupkaite ribbons in the ratio 1:4, is one such geol. Bundesanst., IVien L0L, 323-472. phase. However, attempts to synthesizethe intermediate phases in this series by Springer Harnrs, D. C. & CHEU T. T. (1976): Crystal chemistry and re-examination of nomenclature of sul(1.971.)and Mumme & Watts (1976) were not fosalts in the aikinite-bismuthinite series. Caz. successfulbut confirmed that a complete solid Mineral, t4, L94-205. solution series exists above 3'00oC. The hypo(composition equi- Honrucu, H. & WusNscH, B. J. (1976): The orderthetical phasesCuroPbroBirsSz, ing scheme for metal atoms in the crystal structure valent to friedrichite) with a-6X11.2A (Moore of hammarite, Cu2Pb2BiaSe.Can. Mineral. L4, (composition between 1967) and CuruPbreBiraSeo 536-539. friedrichite and hammarite) with a-5 x lI.2A (1977): Lindstrdmite, CusPbsBiz& (Welin 1966; Moore 1967; Synedek& Hybler Sts: Its space group and ordering scheme for 1975) have not as yet been found in nature.
metal atoms in the crystal structure. Can. Mineral. L5, 527-535. Kouersu, I. & WusNscH, B. J. (1973): The crystal PnEsrnverroN oF TYPE Marrnrer, structure of gladite, PbCuBisSs. Amer, Mineral. 58, 1098 (Abstr.). The mineral is named in honor of Professor Emeritus, Dr.-Ing O. M. Friedrich, Mining MooRE, P. B. (1967): A classification of sulfosalt structures derived from the structure of aikinite. University, Leoben, Styria, Austria for his conAmer. Mineral. 52, t874-1876. tribution to the field of ore genesisin Austria Munar're, W. G. & Werrs, J. A. (1976): Pekoite, during the past fifty years. Type materials will CuPbBillsrs, a new member of the bismuthinitebe preserved at Institute of Mineralogy, Uniaikinite mineral series: its crystal structure and versity of Salzburg, Salzburg, Austria, at the relationship with naturally- and syntheticallyMuseum of Landeskunde Joanneum, Graz, Styformed members. Can, Mineral, 14, 322-333, ria, Austria, at the Royal Ontario Museum, ----, WrrrN, E. & WuENscu, B. J, (1976): Torontdr Canada, and at the U.S. National Crystal chemistry and proposed nomenclature for Museum, Smithsonian Institution, Washington, sulfosalts intermediate in the system bismuthiD.C., U.S.A. nite-aikinite (BirSs-CuPbBiSg). Amer. Mineral. 6t, 15-20. Rucrurncr, J. C. & GesrennrNr, E. L. (1969): AcrNowrsocEMENTs Electron microprobe analytical data reduction (EMPADR VII). Dep. Geol. Univ. Toronto. We would like to thank Drs. D. C. Harris, L. SpRrNorR, G. (1971): The synthetic solid-solution J. Cabri (CANMET) for valuable discussions (bismuthinite-aikinite). series BirSs-BiCuPb$ during this study, and Mr. J. M. Stewart, E. J. Neues Jahrb. Mineral. Monatsh., 19-24, Murray and J. H. G. Laflamme (CANMET) for SvNr6rr, V. & Hvnrnn, J. (1975): The crystal technical assistance.Mr. J. F. Rowland (CANstructures of krupkaite, CuPbBigSo, and of gla(National MET) and Dr. A. Kato Science Mudite, CuPbBigSe, and the classification of superseum, Tokyo, Japan) read the manuscript; Prostructures in the bismuthinite-aikinite group. fessor H. Meixner (Inst. Mineralogy, Univ. Neues Jahrb. Mineral. Monatsh,, 541-560. Salzburg) and Dr. A. Alker (Joanneum Graz, WEr.rN, E. (1966): Notes on the mineralogy of Styria, Austria) provided some material for Sweden 5. Bismuth-bearing sulphosalts from Gladthis study; Professor B. J. Wuensch (M.I.T.) hammar, a revrsion. Arkiv Mineral. Geol. 4' sent us a preprint of the lindstriimite paper; 377-386.
Mrs. L. Stevenson (Redpath Museum, McGill Univ., Montreal) provided probe standards to one of us (E.K.). E. K. and W. P. are grateful
Received September; revised manuscript accepted November 1977.
