American Mineralogist, Volume 65, pages 506-508, 1980 Sundiusite,a new lead sulfate oxychloridefrom Lingban, Sweden Pnrp J. DUNN Department of Mineral Sciences, Smithsonian Institution llashington, D. C. 20560 AND ROLAND C. ROUSE Department of Geology and Mineralogy, University of Michigan Ann Arbor, Michigan 48109 Abstract Sundiusite,Pbro(SO4)Cl2Or, is a new mineral from Ldngban, Sweden.It is monoclinic, C2, Cm,orA/m,witha:24.67(l),6:3.781(l),c: ll.S8l(5)A,B:100.07(4)",andZ:2. The strongestlines in the X-ray powderpattern are (Al, hk|)2.981I0 510;2.7378113;3.101 6 602,603;3.W 6 800,403;6.10 3 400;3.74 3 I 10.Sundiusite occurs as plumoseaggregates of white to colorlesscrystals with an adamantineluster. The Mohs hardnessis about 3, and there is a perfect {100} cleavage.Optically, it appearsto be biaxial (+) with all indices greater than 2.10;lath-shaped fragments are length-slow.The observedand calculatedden- sitiesare 7.0 and 7.20g/an3, respectively.The mineral doesnot fluorescein ultraviolet radia- tion. The composition,as determinedby electronmicroprobe, is PbO 93.1,FeO 0.5, SO33.5, Cl 3.0,less O = Cl 0.7, total 99.4weight percent,which yields the ideal formula Pbro(SO4)Cl2Ot. The composition and cell geometry suggesta structural relationship to the nadorite group. Sundiusite is known only from Ldngban and is identical with Flink unknown #284. The name is for the late Nils Sundius. Introduction not recognized by the Subcommitteeon Amphiboles, This new mineral specieswas found severalyears IMA, in its recent systemizationof amphibole no- ago on a specimen in the collections of the Smithso- menclature (Leake, 1968) and indeed "sundiusite" nian Institution. The new specieswas later identified was not even included in its list of amphibole names as one of those minerals of unknown identity noted which should be abandoned.Since this compound is from Lingban by the mineralogist and collector, unknown as a natural mineral and since the name justified Gustav Flink (1849-1931).Flink published many has not gained popular acceptance,we feel lists of Lingban minerals which he consideredwor- in using sundiusite for the new speciesfrom Ling- thy of further investigation.The referencesto these ban. The mineral and name have been approved by lists are given in a report on the statusof the "Flink the IMA Commissionon New Minerals and Mineral unknowns" by Moore et al. (1971'5. Names.The type spccimenis preservedin the Smith- We take pleasurein naming this new mineral sun- sonian lnstitution collection under catalog#NMNH diusite after the late Swedishmineralogist Nils Sun- 134984. dius (1886-1976)n recognitionof his numerouscon- tributions to the study of Ldngban mineralogy Physicaland optical properties including his classicstudy of the manganiferouspy- Sundiusite occurs exclusively as plumose aggre- roxenoids (Sundius, l93l). The pronounciation of gates of white to colorlesscrystals up to 8 mm in the name is sDri-d-e-us-ite.The name sundiusitehas length. The aggregatesare composedof overlapping been previously used to denote the hypothetical plates, which are slightly offset from one another in a sodic-calcic amphibole, NaCaNaMg3AlrSLOrr(OH), diverging manner. The streak is white and the luster (Phillips and Layton, 1964).However, this name was adamantine.There is one perfect cleavageparallel to 0003-004x/80/0506-0506$02.00 506 DUNN AND ROUSE: SUNDIUSITE s07 {100}. The mineral is quite brittle, breaking easily Table l. Electron microprobeanalysis of sundiusite into lath-shapedfragments, whose longest dimension SUNDIUSITE Theoreti ca1 is parallel to the b crystallographic axis. A possible Pblo(s04)cr2o8 second cleavagemay exist parallel to {001} but is very poorly developed.The Mohs hardnessis ap- Pb0 93.1 94.30 proximately 3. The density, determinedusing a Ber- Fe0 0.5 man balance and temperaturecorrection, 7.0+0.2 s0. 3.5 3.38 is J g/cm', in good agreementwith the calculatedvalue cl 3.0 3.00 '7.20 '1 of E/cm'. Optically, sundiusite appears to be Total 100I 00.68 biaxial (+) with refractiveindices all>2.1. The maxi- Less0 = Cl 0.7 0.68 mum birefringence,determined with a tilting com- Total 99.4 100.00 pensator, is 0.070. Cleavage laths are length-slow. There is no responseto ultraviolet radiation. Sun- Accuracyof data: t3% of the amountpresent. Quantities given diusite, along with blixite, occurson fracture surfaces are in weight percent. of an ore consistingof braunite,hausmannite, calcite, and manganoanbiotite. It is the last mineral of this assemblageto form. There is also a prominent subcell with A : 24.67,B Sundiusiteis similar in appearanceto severalother : 3.?81,C : c/3 : 3.960A,and B: 100.07o.Cell minerals, the most notable of which are hydro- parameters were refined by least-squares from cerussiteand mendipite. The resemblanceto mend- Debye-Scherrerdata utilizing NBS silicon (a : ipite, PbrOrClr, from the Mendip Hills, England is 5.4309A)as an internal standard.The X-ray powder particularly striking. Although neither mineral fluo- diffraction data are given in Table 2. rescesunder ultraviolet radiation, the calcite associ- ated with each has a similar fluorescence.which ac- powder difraction data for sundiusite centuatesthe resemblancebetween mendipite and Table 2. X-ray sundiusite.This has led to someconfusion. a matter dobs oca hkl Iobs ocal hkl lobs I "obs which will be discussedin a subsequentsection. <l 12.0 12.1 200 (2.042 9'r3 Chemistry I 9.29 9.27 201 2.033 <2.024 I2.0.0 I 7.79 7.77 201 12.022 Lt3 Sundiusitewas chemically,analyzedwith an ARL- 3 6.I 0 6.07 400 1.980 1.980 206 1.89] 020,606 <<l {5.82 401 L890 sEuq electronmicroprobe, at an operatingvoltage of r'tE Is.oz 202 1.826 1.825 ll.l.3 15kV and a beam curent of 0.15pA, determinedus- <t 4.03 4.05 600 I .807 I .807 9t3 203 1.805 420 ing a beam current monitor. The standardsused were t J'' t+ 13.917 i s,gsg oo3 'I1.75? 515 PbO for lead, celestine for sulfur, hornblende for 3 3.744 3.736 l l 0 <1 1.747 .751 316 1.748 lt6 iron, and halite for chlorine. A wavelength-dispersive (3.578 403 2b 3.553 (3.537 203 (r.7r0 il6 scan indicated the absenceof any other elements 13.532 l1I r 1.704 {I.701 023 2 3.428 3.426 3t0 tt.ogs ]a'o'3 with atomic number greaterthan nine. The data were <l 3.349 3.356 3lI ,1.580 l?.0.3 l3.l.o correctedusing a modified version of the MAGIC-4 ' t 'oto ft.ozs a 1 rnr J3.091 603 lt,slz 423 program. The resulting analysisis presentedin Table t 3.086 602 ,1.67t 007 . 1 ^^A J3.048 403 l. Calculation of the unit-cell contentsusing the ob- I 3.036 800 r 1.657 1.657 716 316 I 0 2.981 2.984 510 I r.orv J].643 serveddensity yields Pb,rrFeorSroClrrOrruin good lt.oos l3.l.3 f I .607 423 <<l 2.892 2.911 802 z r'oud agreementwith the theoretical composition Pb,o I 2.737 2.735 ll3 lt.oos gzo <l 2.628 2.629 803 (SOn)ClrO8with two formula weights per cell. Sun- 7ll <<l 1.551 i.546 12.0.6 <l z'"t 12.567 lz.sso 710 (1 .4e2 10'2'0 diusite is chemicallyhomogeneous and is very slowly I 1.490 (1.491 14.0'3 (t 'I '0 solublein l:l cold HCI or HNO,. <<l cn1 il? Ir.qee 5.1 2.4e1 \r"i6i 3i3 I 1.368 (2.433 71',l z z'qzd Crystallography \z.qzg lo.o.o <<l 1.353 i2.277 713 <<l 1.267 | 1'ztq \z,zls I 14 <1 1.244 Sundiusite was studied by Weissenberg,pre- <<l 2.186 2. I 95 604 <1 1.220 cession,and oscillating crystal methods.The mineral I 1.20t is monoclinic,A, Cm, or A/m, with c :24.67 esd ,l'l4.6 0.01,b : 3.781esd 0.001, and c : I1.881esd 0.0054, m Debye-Scherrercamera' CuKa radiation, NBSsilicon internal standard, b = broad line F : 100.07esd 0.04", and V: l09l.l esd 0.84'. 508 DUNN AND ROUSE: SUNDIUSITE The subcell dimensions of sundiusite suggest a two minerals are identical (Flink #285 is blixite). relationship betweenthe new mineral and members However, we note that Moore et al. (1971) attribute of the nadorite group. As shown in Table 3, the lat- #284 ro mendipite on the basisof density and single- tice parametersof orthorhombic nadorite,perite, and crystal X-ray photographs.Subsequent to our char- blixite are related to those of synthetic tetragonal a;clerizationof sundiusite, a number of specimensof nadorite (SN) such that a = c = asNJ2 and b = cr* Flink #284 were located in the Flink collection at or 2csN.In other words the basic geometrical unit Harvard University. Both sundiusiteand mendipite common to all of them is either tetragonalor pseudo- were identified by powder X-ray photography on tetragonalwith parametersA = 4 andc = l2A. This these specirnens,but the two minerals do not occur correspondsto the sundiusitesubcell with its A pa- togetheron any one specimen.Hence, Flink number rameter halved. It may also be noted that nadorite 284 was probably assignedto two separateminerals, and its congenerspossess a single perfect cleavage which would have been difficult for Flink to distin- perpendicular to their 12 (or 25) A translation, re- guish by sight or density measurements,the densities flecting the layered character of their crystal struc- of sundiusiteand mendipite being 7.20 and 7.22 e/ tures (Giuseppettiand Tadini, 1973).Sundiusite also cm', respectively.Mendipite has also been reported possessesa single perfect cleavagenearly per- from Lingban by Gofli and Guillemin (1953).