211+ Which, Combined with the Microprobe Analysis, Gives a Total Of

211+ MINITRALOGICAL NOTES

which, combined with the microprobe analysis, gives a total of 99.9 percent. The X-ray powder pattern, indexed on Evans and Allmann's hexagonal cell vields cell dimensionso 3.778 and.c 34.147.A which are in close agreementwith that of normal valleriite oI a 3.792 and c 34.10 A. The Noril'sk mineral appearsto representthe end member of a seriesof "valleriite-type" minerals with the Mg-Al positions in the hl,droxidelayer occupiedb.v Fe.

Acxxorvr,Blcrnrxr

We r,vish to thank Dr J. Rucklidge, University of Toronto, who suggested the "valleriite-type" formula from our microprobe analysis

I{rlrnrNcns

Caenr, L. I. 0967) A nerv copper-iron su1fide.Econ. Geol.62,9L0,925 exn R. J. Tnr,rr,r. (1966) New palladium minerals from Noril'sk, Western Siberia. Can. Mineral. 8, 541-550. Cu,trtrrnr..trm, J. A., eno R. N. Dnreero (1965) Mackinalvite and valleriite in the Muskox intrusion. Amer. Mineral 50,682 695. IivaNs, H. T., Jn., ano R. Ar.r.ulNN (1968) The crystal structure and crystal chemistr.v of valleriite. Z. Kristallogr., 127, 73-93. GnNr

THE AMERICAN MINERALOGIST, VOL .'5, NOVEMBER-DIICEI\{BER, 1970

TUNGSTENIANWULTENITES, MINA SAN SAMUEL, CACHIYUYODE LLAMPOS,CHILE AraN H. CrAnr, Department oJ Geologi,calSciences, Queen's Linirer sity, K in gston,Ontario, Can ada

AND Rrcnenl H. Srr.r.rron,Instituto de Inaestigaciones Geollgi,cas,Casil,la 10465,Sontiago de Chile.

ABSTRACT

Chemical analyses and cell dimensions are presented for a wulfenite and for two Pb(Mo,W)Or solid solutions from northern Chile. The latter are more molybdenum-rich than previously described "chillagites", and indicate that a complete series from wulfenite to stolzite may be represented in nature. MINDRALOGICAL NOTIIS

Ilrrnooucrrox Whereas complete solid solution between tetragonal PbMoO+ and PbWO4 has been establishedby synthesis (Jaegerand Germs, 1921), few occurrenceshave been describedof minerals with compositionsinter- mediate betweenthe natural analogues,wulfenite and stolzite.Of these, the "chillagite" from the Christmas Gift mine, Chillagoe,Queensland, appears to comprise a comparativell' wide range of compositions from, approximately, wulfeniteT3to wulfenite51.5(Ullmann, 1913; Smith and Cannon, 1913;Mingaye, 1916),and remainsthe best-documentedrepre- sentative of the series.Wiliams (1966) found that three of sixty-four wulfenites from various localities contained ) 2 percent tungsten, but did not provide completeanalyses of thesephases. Syritso and Chernik (1966)and Mexiner (1969)have provided lessdefinitive analytical data for probable,molybdenum-rich members, while Easton and Moss (1966) report an anlysis of a stolzite containing a small amount (0.8 weight percent) of MoOs. Publisheddata (Smith and Cannon, 1913 Quodling and Cohen,1938; Syritso and Chernik, 1966; Williams, 1966) for the cell dimensionsof the naturally-occurringPb(Mo,W)O+ solid solutionsare scanty and, in part, inconsistent with the values found for the synthetic end-members by Sill6n and Nylander (1943). In the present note, we record the occurrenceand compositionsof wulf enite-stolzitesolid solutions from a new locality.

WurnnNrrB rN THE Coprap6 AneA, Csrrn Wulfenite is a widespread,though generally minor mineral in the oxidation zones of copper-polymetallic ore deposits in the Copiap6 mining district of northern Chile (Sillito e, 1969),almost invariably representing a transportedphase. In rnost occurrences,it displaysthe bright, orange- yellow color and adamantine luster characteristicof the species,and forms tabular crystals up to 3 cm in diameter. Locally, however, markedly paler, straw-yellow colors are exhibited, suggestive(Palache, et at., lgSI) of the partial substitution of molybdenum by tungsten, or (S. A. Wil- liams, in Hoffman, 1968) the existenceof structural defects. Material for analysis was collected from the dumps of the small San Samuelcopper mine (Lat. 27"4.4'S.; Long. 70o0.11W.),which works a body of brecciated and tourmalinized quartz porphyry. Molybdenite is a major constituentof the hypogeneore, which locally assays2.5 percent Mo (Varlamoff, 1963), while scheeliteoccurs in smaller amounts. At this locality, the wulf enite forms unusually large, free-standing euhed- ra, overgrowing hydrothermally altered granodiorite along fracture planes, and ranging in color from medium orange-)'ellowto straw- 21r6 ].[ I N ],:RALOGICA L NOT'I'S

Tarr,r i. Arer.vsrs eNn Cnr,r.DruoNsroNs or Wur,r'rxrtr Sror-zrrn Sorro Sor,urroNs.Coprep6 Drsrnrcr. Crlr.r

Chillagite, I 2 3 PbMoOr Mina nrlno uinu Queensland Pbwor { ullmann' Dulcinea SanSanruel SanSamuel rs1.3)

CaO 0.30 n.d.' n.d Pbo 60.78 60.01 58 85 57.66 .54 2.5 ,19 0.5 MoOr 39.22 39 03 32 70 28.65 17.52 WOs 0.57 8.40 13.74 28.22 50.9.5 Total 10000 99 9r 99.95 100.05 99.99 100.00 aA 5 424b 5.430" 5.428" 5.431" 5.44d 5.448b CA 12.o76 t2.074 12.064 12.060 t2.10 12.016

" Not detected ( " Sillin & N1'lander,1943 + 0 00.5A). " +0.005A d Convertecl from frr units (Quodling and Cohen, 1938). yellow. The wulfenite crvstals are, however, not delectabll- zoned in hand-specimen.They are largel)' flat, tabular on {001}, with edges dominatedb1' { 11a} , {013} , and {011} (c/. Williams, 1966),but the paler individuals show a greater developmentof pyramidal faces,and several exhibit predominant steep,dipyramidal { 111} f orms (c/. Williams, 1966, Fig. 1D).

Ax,q.lvrrcer, Drlrn Two pale yellow dipyramidal crystals,of 2.5 and 2.7 cm in maximum dimensions,were separatedunder a binocular microscope,and analysed following the proceduredeveloped b1" Easton and Moss (1966),which is specifically designed for the determination of coexisting molybdenum and tungsten. X-ra-y fluorescencescans were also made in search of Fe, V, Cr, As, Sb and other minor elements;these were, however,not detected. In addition, an orange-yellow,tabular crystal from the nearbl' Mina Dulcinea de Llampos was analysed. The analytical results are presentedin Table 1. The cell parametersof the three analysedspecimens were determined in a Nonius Guinier-de WoIff quadruple-focussingcamera, using Co-Ka radiation, and silicon as an external standard (Table 1). The analysesof the two San Samuel crystals satisfy the requirements of stoichiometric Pb(Mo,W)Or solid solutions, intermediate,between wulfenite and stolzite. Thesepha,ses are Ca-fr.ee,but the W-poor material MINERALOGICAL NOT'ES 2t17 from Dulcinea contains minor amounts of that element. Palache et al. (1951) quote an analysis of a wulfenite from Chile with 6.88 percent CaO, and complete solid solution of the lead and calcium, scheelite- type tungstates and mol.vbdates iryouldbe expected, although the few published analysessuggest that natural representativesmay in general conformrather closell'to the four boundingseries. 'fhe San Samuel phasesare markedl)'poorer in tirngsten than most previously described"chillagites," and indicate that a complete solid solution seriesfrom wulfenite to stolzite may indeed be representedin natural assemblages.The o and c parametersof the solid solutionsdis- play an essentiallylinear relation with those determinedfor synthetic PbMoOr (o 5.424,c 12.076A) and Pb\r\'Or(o 5.488,c 12.0t6 A) ll SiII6n and Nylander (1943). The value of c:t2.t0 A [converted from the original kX units using Bragg's (.1947)factor 1.00202]found for the type chillagite of Ullmann (-55.4 mole percent PbMoOr) by Quodling and Cohen (1938)may, therefore,be in error. The wulfenite from Mina Dulcinea has cell dimensions similar to those of sr.'ntheticPbMoOr.

Drscussror Neither the Dulcinea wulfenite nor the tungsten-bearing phasesfrorn Mina San Samuel are intimately associatedwith other oxidate lead minerals, and the Eh/pH conditions of their formation cannot therefore be estimated with confi.dence(cf . Wiliiams, 1963, 1966). However, the observationssummarized herein suggestthat there mal-be a rela- tionship between the tungsten content of wulfenite and the color and habit of this mineral in thesedeposits, the more tungsten-richmembers displaving paler yellow colors and dipl'ramidal rather than tabular forms. This would be in conflict with the conclusionsof Williams (1966), who proposed that the conditions of deposition, and not major or minor element concentrations,are the dominant controls on wulfenite habit; it is not known whether he examinedspecimens from northern Chile. As Palacheel al. (l9i>l) suggest,the name chillagiteis probably super- liuous as a descriptionof intermediatemembers of the wulfenite-stolzite series.IIowever, becauseit has attained some currenc)-,it might be re- tained for compositionsbetween 20 and 80 mole percent PbWO,r, b)- analogl'with the wolframite series.

AcKNowLEDGEMENTS

Field work in Chile (A.H.C.) is financed bJ' the National Research Council of Canada and the Instituto do Investigaciones Geol6gicas, and is carried out in co-operation with the Iatter orsanization. 2tt8 MIN]JRALOGICAL NOTES

Rnrrrnxcns Bnacc, W. L. (19+7)Letter to the editor. Amer. Mineral.32,592. Ea.srox, A J., ar.rn A. A. Moss (1966) The analysis of molybdates and tungstates. Mineral. Mag. 35,995-1002. Holruan, V. (1968) The'Mi.neralogy oJ the Mapi,mi Mi.ni.ng Distriet, Durongo, Merico. Ph.D. Thesis, Univ. Arizona, 230 p Jercnn, I'. M , aNo H. C. Grmrs (1921) Uber die biniiren Systeme der Sulfate, Chro- mate, Molybdate und Wolframate des Bleies. Z. A nor g. ALlg. Chem. ll9, l45- 173. MnrxNrn, H. (1969) Stolzit und Angiesit aus Bulgarien (mit Bemerkungen zum ange- blichen Stolzit von Bleiberg, Kiirnten). Neus. Jarb. MineraL. Abh. 112,9G100. MrNcevn, J. C. H. (1916) Contributions from the Departmental Laboratory: notes on chillagite. Rec. Geol'.Surt. N . S. W al'es,9, 17l-17 3. Perecrrr, C., H. BnnuaN, eNr C. Fnonorr- (1951) TheSystem oJ Minerol'ogy . . . of Dana, 7th Ed.,tol,.2, John Wiley, New York, 1124p. Quoorrnc, Fr,omm, eNl S. B. Connu (1938) An X-ray examination of chiliagite. J. Proc- Roy. Soc.N. S.Wales,7l,543-546. Srr.r.6N,L. G., .tur Anma-LrsA NvLANDER (1943) On the oxygen positions in tungstates and mol1'bdates with the scheelite structure. A r k. K emi', M iner al. Geol., 17A no. 4, l- 27. Srrrrron, R. H. (1969) Stud.ieson the Controls and. Mineralogy of the Supergene Alteration oJ CopperDeposits, Northern Chi.le.Ph.D. Thesis, Univ. London,498 p. Snrrn, C. D., aNo L. A. CexmoN (1913) Crystal measurementsof chillagite. J . Proc. Roy. Soc. .ly'."1. Wales,46,207-217. Svnrrso, L. I,'., AND L. N. CnnnNx (1965) [Evolution of the paragenesis of accessory minerals during metasomatic alteration of granites in an eastern Transbaikal massif.] Zop. V ses.Mineral Obshch.94,383-400[in Russian; Mi'neratr.Abstr. 19,55 (1968)]. Ur,r,uaNr*,A. T. (1913) A new mineral J Proc. Roy. Soe. N . S. Wales,46' 186. V.lnr.Alrorr, N. (1963) Geol,ogical,ond, Mineral, Surtey oJ Northern Chi'le. United Nations Spec.Fund Rep., 56 p Wrtr.raus, S. A (1963) Oxidation of sulfide ores in the lVlildren and Steepe mining dis- tricts, Pima County, Arizona. Econ.GeoI.58, 1119-1125. -- (1966) The significance of habit and morphology of wulfenite. Amer. Mineral' Sl, 1212-1217.

THE AMERICAT\ MINERALOGIST, \'OL ss, NO\TEMBER-DECEMBER, 1970

EICOSYL AICOHOL: AN ORGANIC CONSTITUENT OF CALCITD FROM DEUTSCH-ALTENBURG, AUSTRIA

Cuanr-Bs J. Kelr.v, Ju.,r Nezu England Insti.tute, Ridgef'eld, C onnecticut 06 877 .

Assrnecr Analysis of red-tinted calcite from Deutsch-Altenburg,Austria, probably of Miocene age, failed to confirm the existenceof a metal porphyrin compound as reported by H'

I Presentaddress: Hubbard-Hall Chemical Co , 563 S. LeonardSt., Waterbury,Con- nccticut06708.