167 Thz Canadian M incralo gist Vol. 35, pp.1,67-173(1997)
LITHIUMIN SEKANINAITEFROM THE TYPE LOCALITV, DOLNIBORY. CZECH REPUBLIC
PETR dERNfI anp RON CHAPMAN
Departrnentof GeolagicalSciences, University of Manitoba, Winnipeg,Manitoba R3T2N2
WERNERSCHREYER
Irutitut fir Mincralogie, Ruh.r-Uni'ttersitiltBoclun D44801 Bochwa Germary
LIIISA OTTOLINI AND PIERO BOTTAZZI
CNRCentro d.i Studio per la Cristallochimicae la Cristall.ografiaI-27100 Pnia ltaly
CATIIERINEA. MoCAMMON
BayerischzsGeoinstitw, UniversbAtBayreutfu D-95440 Bayreuth. Germany
ABSTRACI
The (Si,Al)-orderedFe end-memberof the cordieritegroup, sekaninaite, from its type locality at Dohl Bory, CzechRepublic, was analyze4 and found to contain0.04 - 0.2ALi ard0,1.l -0,2-6Na apfu; (Fe + Mn)/(Mg + Fe + 1!tn) (at.) rangesfrom 0.74 to 0.97.Lithium is incorporatedby the substitutionchNavlli0\4gFe)-r . This sekaninaiteis the first memberof the cordieritegroup reportedto have substantialLi but negligible Be. All samplesof Na,Be-, NaJ-i'Be- and Nati-bearing cordierite-sekadnaite examinedto date show a minor deficit in the tetrahedralsite (0,237 in the literature, 0.036 in our data) and a slight excessof channelcations (NaKCa) over the proportion of (BeIi) (at.). The Li-bearing sekaninaitecomes from ralher simple granitic pegmatites,in which the only Li-bearing minerals are rare tiphylite and cookeite.Thus cordierite-groupminerals are crystal- 'Ihis chemicalsinks for U. ffnding stressesthe needto analyzefor tracelight elements,even in mineralsfrom poorly fractionated andrare-element-depleted environnents, provided the crystal chemistryis favorable.
Keyvvords:sekaninaite, cordierite group, lithium, beryllium, CzechRepublic.
SoMraans
Nous avonsanalysd la sekaninalte,p61e ferrifbre ordonn6en Al,Si du groupede la cordi6rite,provenaat de sa localit6 type, i Dolnl Bory, en R6publiqueTch{ue. Elle contient entre 0.M et0.24 atomesde Li et entre 0.11 et 0.26 atomesde Na par unit6 formulaire. k rapport @e + NIn/(Mg + Fe + Mn) (ar.) va de 0.74 d0.97.I.e lithium est incorpor6 selon le schdma ooaNavtli(Mg,Fe)-1. Cette sekaninaltefoumit le premier exemple d'un membre du groupe de la cordi6rite contenantune proportion appr€ciablede Li, mais en m6me temps, une proportiotr ndgligeablede Be. Tous les exemplesde cordi6rite - sekaninaltecontenant NaFe, NaIi'Be et NaLi 6tudi6sjusqu'ici font preuve d'un l6ger d6fcit d'occupation dans le site t6traddrique(0.237 dans la litt6rature,0.036 pour nos donn6es),et d'un l6ger exc€denten teneursde (NaKCa) daasles canaux par rapport arrltteneurs en (BeIi), en proportionsatomiques. la sekadnaltei Li provient d'exemplesde pegmatitegranitique relativenent simple, danslesquels les seulsmin€raux i contenirle Li essetrtielsont triphylit€ et cookeite,rares. C'est donc dire que les min6rauxdu groupede 1acordi6rite seraient un h6te privil6gi6 du Li. Cette situationsouligne la ndcessit6de chercherb 6tablir les teneursen 6l6nents l6gerse f6tat de trace,m0me dans les min6rauxprovenant de milieux peu 6volu6set appauwis en 6l6mentsrares, pourvu quela situationcristallochimique en est favorable. (Traduit par la R6daction)
Mots-cl6s: sekaninalte,groupe de la cordi6rite,lithiun" bdryllium, R6publiqueTchdque.
L E-mail address: [email protected] 168
INTRODUC"noN TABLE I. SAMPLESOF THE DOTNIBORY SEKANINAITE DGMINED Sekaninaite,ideally Fe2AlaSisOrr,is the Fe-domi- nant andAl-Si-ordered memberof the cordieritegroup. Sou@ Na?O;wt.%t It was synthesizedby severalauthors ['Terrocordierite" )c R&srch collection of J. Stan& 130 of Schreyer(1965); cl Boberski& Scbreyer(1990)1, x6 Recgarc.hco|letio of J. Stantrk 130 (L928), first noticed as a natural mineral by Sekanina )(}3 DepL Mheralogf, Petrograpby and 0.45 describedas a new speciesby Standk & MiSkovskf c€@henidry, Masaryk University. No. 11220 Q975:cf. Standk& Mi5kovskf 1964),and also studied D€pL Mintralos| and Petrology, Mor$'iatr 0J0 by electronmicroprobe (Goldman et aL 1977,Selkregg Mureu6- No. 691
& Bloss 1980, Scbreyer et al. 1993) and by X-ray DepL Mrcrslory and Petrology, Moraviu 0s2 diffraction lstructure refinement by HochelTaet al. Museun" No. 1185 (1979), unit-cell dimensions and selected physical Dept, Mn€ralog| and Potrology, Muavian 095-ll)3 propertiesby Sellregg & Bloss (1980)1.In 1990,during !fusm No. a583 the initial stagesof examination of associatedferro- Depc Mneralogr and Petrology, }{6sviar 1.08-118 gedrite, elecfton-microprobeanalyses @MPA) were ![usus, No. al44l performedattheUniversity of Manitobaon sekaninaite Rearch colection of W. Schnla (0e0) from its type locality at Dolnf Bory, westemMoraviq Czech Republic. The analysesyielded totals slightly tReconnaiesancedata deterniaed by teging all of the 46 specimers lowerthan expectedfromthe previouslyknown content availablo fc sudy, qc€'pt TS25. of H2O+,and formulas deviating from tle ideal stoichiometryOigh levels of Na but deficit in the octa- hedrally coordinatedsites). The stoichiometryruled out Axalvrrcar lMBrnonsaNo MOsssAuERRESLILTS potential substitutionby Be, and Li was not seriously considere4 as the parentgranitic pegmatitesare virtu- EMPA analysesof sevenspecimens at the Univer- ally devoid of lithium-bearingminerals. The low totals sity of Manitoba were done using o CamecaSX-50 werefirst afiributedto improperstandards, but re-analysis instrument,with an operatingvoltage of 15 kV and a of the examinedspecimens at the Rubr-Universitiitcon- samplecurrent of 20 nA, measuredon a Faradaycup; firmed the resultsobtained at Manitoba. pres- Thus the counting time was 20 s for the Ka lines of Na (albite enceof Li remainedthe only viable possibility, and was standard),Fe (fayalite), Si (diopside),Mn (spessartine), subsequentlyconfirmed. We report here on our results Al (kyanite) and Mg (olivine), and 40 s for Kcr of K of extensivechemical analysesof sekaninaitefrom its (orthoclase),Ca (diopside),Ti (titanite), Cr (cbromite), type locality, and on its geochemicalsignificance. Zn Gahnite),F (fluor-richterite), andIa of Cs (pollu- cite) and Rb (rubidian microcline). The data wetrere- SevprrsExevnrro ducedusing the PAP procedureof Pouchou& Pichoir (1985). The high contentof Na found in the first Li-bearing SIMS analysesof the above specimensfor Li, Be specimensexamined suggestedtlat tle presgnceof and B wereperformed atthe CNR Centrodi Studioper octahedrallycoordinated Li could be compensatedby la Cristallochimica e Cristallografia in Pavia under incorporationof Na inlo the channelsof the stucture. analytical conditions fully describedby Oltolint et aL Atotal of 2i7samples of sekaninaitefrom the collection (1993). Briefly, positive ions of the isotopes7Li, eBe of the Moravian Museum,and eight samplesfrom the and 11B(plus 30Si, assumedas the matrix reference collectionof the Departuentof Mineralogy,Petography isotope), rvith emissionkinetic energiesranging from and Geochemistry,Masaryk University were analyzed ^:75 to L25eV, weremonitored using a CamecaMS-4f by elecfronmicroprobe for Na as a monitor of Li, along ion microprobe.Medium- to high-energysecondary ions with two samplesfrom the R3. FergusonMuseum of were usedto reducematrix effects a.trectingaspecially Mineralogyat the University of Manitoba,four samples Li-Si ionization and to improve measurementrepro- from the researchmaterial of Dr. J. Standk (Masaryk ducibility with respectto low-energyion analysis.The University) andthree samples from the researchcollec- quantification of Li, Be and B ion signalswas canied tion of P.C. Sevenspecimens covering the full rangeof out by means of the empirical approachof working Na2Oencountered 0.13 - 1.57wt.Vo, wata selectedfor curvesvla calibrationwith standards.Since the relative detailedanalysis by EMPA, secondary-ionmass spec- yields for Li ions, with emissionenergies in the range fomety (SMS) andMdssbauer spectroscopy Clable l). 75-125 eV. showeda direct correlationwith the silica A specimenof sekaninaitecollected at Dolnl Bory in contentof the matix (Ottolini s1aL 1993),an empirical 1963 by W.S. (TS 25) was analyzedat the Ruhr- correctionwas made to accountfor matix effectsat this Universitdt, and also was subjected to Miissbauer silica value: for the quantificationof lithium, we used analysisClable l). an ion yield that is typical of low-silica samples,which LJTIIIUM IN TYPE.I.OCALITY SEKANINAITE 169 is lower by abouI25%othan that of high-silica samples. Wet-chemicalanalysis was performedfor Li andBe on No specialconections were employedto quantifyberyl- material cleaned under a binocular microscope.The lium or boron contents.Under thesecircu.nstances. the concentration of both elements was determined by accuracyfor Li (aswell as Be andB) is estimatedto be inductively coupled plasma - emission specfroscopy. betterthan LIVorelative. Reproducibility for Li, Be and This sample was also subjected to the Milssbauer B measurementswithin a one-day analytical session spectroscopicexamination discussed above. was typically afew Vorelative; it was testedon homo- geneoussynthetic glass standards. CIIEI\fiCAL CONFOSIIION OF SEKANINAITE The concenfrationsofli, Be andB reportedhere are the averagesof five determinationson each sample. Table 2 shows the combined results of EMPA, Lithium was found in the range of 0.11 - 0.55 wt.Vo SMS, Mti'ssbauerand in the case of sampleTS 25, oxide; Be and B were found to be negligible (tens of wet-chemicalanalysis. The Fe2O3contents could not be ppm oxides),insignificant for the formulae. quantified.To documentthe presenceof Fe! indicated The M0ssbauerspectra were collectedat the Bayer- by the medium to deep blue color of sekaninaite,its ischesGeoinstitut in Bayreuth,using powderedmate- contentwas fixed for all samplesat the detectionlimit rial in a conventional transmission Mdssbauer of the Mdssbauertechnique, corresponding to the maxi- spectrometer.Sample thicknessesvaried from 2.5 to mum possible (although in most casesunlikely) Fel 5 mg Fe/cm2,depending on the amount of material contentsof samplesX-3 andX-6 (asdiscussed above). available.The room-temperatureMdssbauer specta of Any enor involved in this procedureis ftivial, because all samplesare identical, consistingof one quadrupole assigning 0.5Voor less of Fe to the trivalent state doublet with hyperfine parameters6 = 1.21,2t 0.005 instead of none has negligible effect on the atomic (relative to cFFe) and AEq = 2.23 t 0.01 mm/s. These contentsof other elements. parametersare consistentwith Fd* in the octahedral site, and are in excellent agreementwith results of previousstudies @uncan & Johnstonl9T4,Goldmatet al. 1977).We did not find spectralevidence for Fe2*in TABLE 2. CEEI\,IICAL COMPOSIION OF SEKANINAITE FROM DOIJ'II BORY the channelsites, nor for Fe3*.To determinethe mini- Smples ,(33 )G9 X38 Ts25 X5l ,(3 XA X6 mum detection-limit for Fe3*,we fit all specfa to an Siorqi% 45.47 624 44.62 44.42 45-C3 45J6 4495 45.61 additional doublet conespondingto Fd+, and used an 1".o" 0.@ 0.m 0.00 0.00 0.m 0.00 0.@ o.vt At o, 3095 31.41 30a9 31J8 3036 3080 30 n9 F test to determinethe level at which addition of the BrOs 0.002 0.@2 0.004 - 0.003 0.m4 0.m3 0.@5 doublet is statistically significant (e.9., Bevington FqOr. 0.09 0.09 0.r0 0.10 0.10 0.10 0.@ 0.10 GrO! 0.01 0.01 0.00 - 001 0.00 0.01 001 1969).The measuredvalues for FelDFe were all close FeO l5J9 l5.R 18.06 18.m 17.f/ 1739 l6J8 nn to 0.57o,but in only hvo specta (samplesX-3 andX-6) I\,lno 053 0.70 0.96 l.@ 138 ln 1.8'/ 1.40 presence 78O 0.01 0.00 0.m - 0& 0.03 0.01 0.01 was the of Fe3+statistically significant at Mgo 3.06 2-@ 1.05 0a5 038 0.42 033 042 higher than the 50Volevel.This implies that the amount C&O 0.04 0I)5 0.06 0.04 0g) 0.m 0.01 0.03 of Fe+ in the remainingsamples is lessthan 0.5Vo,and BoO 0.008 0.m6 0.@ 0.0q2 o.ml o.ml 0.m 0.m1 Liro 0.1o/ 0.169 0.169 035 0.415 0.474 0.489 0J5r therefore below the detection limit. For samples l{a.o 0J4 059 0J4 090 l.1l 123 1.16 1.19 X-3 and X-6, the amountof Fe& could possiblybe as KrO 0.06 0.m 0.01 og2 0.01 002 0.01 001 cs.o 0.m 0.m 0.00 0.m 0.@ 0@ o01 0.00 high as 0.57o,but is likely lower. HlO+ -Lm It is interestingto notethatthe color andpleochroism TOTAL 96.X7 n:m %.655 9.10 95lf9 nng 95J55 n.6n of Fe-bearingcordierite are interpretedto arise from si 4968 498/ 4940 49m 5.010 4.ry8 5.00, 4984 charge transfer between octahedralFeP* and Fd* in Ar 3986 39D4 4.030 4In 3981 3952. 3910 39B1 ts' 0.@/ o.ffi 0.m 0.m8 0.06 0.@ 0.008 0.m channe(?),letrahedral or octahedralsites (Goldman er Bo 0.003 0.m 0.001 o.mr 0.0m 0.0@ oml 0.0m al. 1977,Boberski 1987),which would imply that our pt ag$ 8988 8.y79 8986 8999 8988 8988 8983 samplescontain Fe3*. However, very lifile Felt is required F* r.425 1.419 1372 1659 1J88 1J95 lJ45 1J78 to produce sufficient absorption for a blue-to-violet Mg 0.498 0.42A 0.173 0.1,10 0063 (1069 0.055 0368 IUn 0.058 0.065 0.090 0.095 0.130 0.113 0.176 0.130 color to be visible, sinceextinction coefficients ofinter- zn 001 0.0m 0.m - 0.m 0.002 0.001 oml valence charge-transferbands are typically 10 to lJ 0.m 0000 0.0m 0.000 0.000 0.m0 0.0@ offil 100 times greaterthan those'for spin-allowedcrystal- G 0.001 0!0r 0.0@ - 0.001 0.0@ 0.ml 0.m1 Li 0.045 0.069 0.o/5 0.154 0.r$ ut$ 0.$ 0,39 fi.eld nansitions @urns 1993). A value of Fd*DFe uE 2frA 1918 2010 2.048 1965 1988 1998 2-019 certainly lessthan 0.57owould be sufficient (Goldman Na 0.114 0.145 0.159 0.193 0239 O25Z 0251 0252 et aL L977).he sameMtissbarer analysis was performed K o.oG 0s00 0.m1 0.m3 0.ml onG 0.001 0.mr to determinethe delectionlimit for channelFdt: it was ca 0.@5 0.m6 o.ff/ 0.005 0.ff2 0.W, 0.@1 0.u14 alsofound to lr-0.SVo. 6:D otn ot52 0.167 0fr1 0242 0Zl2 025? ort, The sampleTS 25 examinedat the Ruhr-Universitiit H,O - 0:143 was analyzedon the CamecaCAMEBAX insftument Calqld @ tb bosis of 18 dme ol cyga pe @ty&qs f@la "dt under conditions analogousto those stated above. I se tsd f@ or0lad@ - cmrotado !d de@tord. r70 TI{E CANADIAN MINERALOGIST
The atomiccontents were assigned to the tehahedral, is the first member of tle cordierite group known to octahedral,and channelsites in the conventionalmannef,' incorporatesubstantial Li but negligible Be. Clable 2). The only degreeof uncertaintyconcerns the Lithium is incorporated into the octahedraby a role ofFe$, which is listed astetrahedral in accordance coupled substitutionchNavll-i (Mg,Fe)-r, suspectedin with its most commonrole, well documentedby eernf natural cordierite by Armbruster & Irouschek (983), & Povondra (1966), among others, and favored by confirmed in natural sekaninaiteby Gordilo et al. Scbreyeret al. (1990). Altematively, Fd+ could reside (985), and experimentally verified in end-member in the octahedraor, possibly,in the channels(Goldman cordierite by Kirchner et al. (1984). The substitution et al.1977,Boberski 1987). LiSi(Me,FelAl)-1, proposedbut unprovenby Ginsburg & Savrov Q961),possibly shown by resultsof an ancie,nt DIscussIoN analysis by von Kokscharow (1858), and potentially exhibitedby experimentalproducts of Karkhanavala& Hummel 0953), is not involved. Howeverothe content TheformaLa of sel Na = 0.9248(Be + Li) + O.M22 (r = 0.9660) (tr) and Na = 0.948(Be + Li) + 0.M22 -a .t a, (r= 0.940) @) ,,il tl As shown in Figure 2, the ratio Si(Al + Be) is ()E somewhatvariable, albeit largely within the limits of N experimentalerror. The substiflrtionNaAlSi-l mayaccount + for the Si-deficient samplesTS 25 and X-3; for the Y othersamples, which seemto be Aldeficient the substi- + El artionNaMgALl can be invoked (Frg. 2). Both mecha- z nisms were proven experimentally and in natural specimens (Schreyer 1964, Wolfsdorff & Scbreyer 1992). Altematively, the excessNa could be charge- balanced by introduction of (Otf- groups attached o.o o.l o.2 0.3 0,4 0.5 directly to Nal+in the channels.So far, hydroxyl hasnot Be+ Li (opfu) been documentedin minspls of the cordierite group (e.9.,Schreyer 1985; P. Miryal{ pers.comm. 1.995), Ftc. l. Sumofthe chmgeson the channel-hostedcations yerszs althoughAurisiccffto et al. (1994)provided convincing total of @e + Li). Samplesof sekaninaitefrom Dolnf Bory evidencefor Na(Otf couplesin the channelsof beryl. are markedby solid circles. I to 3: Alpe Spondq 4 and 5: Miregen, 6 and 7: Haddarn (Armbruster & Irouschek It must be stressed,however, that the deviationsof 1983);8 to 10: H Pen6n(Gordillo et aI. 1985);1 I and 12: the sekaninaiteformula from ideality are very small, Soto(Schreyer et a|.1979);13: V6tnd (eemy& Povondra and do not exceedanalytical error. Slight inaccuracies 1966).Regression lines: I: sekaninaiteDohrl Bory, tr: all in calibrationfor someelements may accountfor some data,m: data from the literarure (1 to 13 above).See the of the systematicshifts, as shown by ooerrof'bars in text for regressionequations. Figure 3. This graph illustratesdeficit in occupancyof LITHIUM IN TYPE-LOCALITY SEKANINAITE 171 { t { CI tt F ,\{ X[ aEer { t + o. o + g N+ { + c o (D = ++ N |E ats ax6l att !o,e7%. = troo tl 8.95 9.OO Si (opfu) td lvt (osi+Al + Be+ Fe3+)(opfu ) Flc. 2. Sumof @e + Li) versusSi. Symbolsand sample Frc.3. Sumof octahedrallycoordinated cations versas sum of numbersare as in Figure1. End of the vectorextending tetraledrallycoordinated cations. Symbols and sample from sample13 marks approximate plot of this cordierite numbersare as in Figure1. Notethat the sumof tetrahe- sampleif its terahedrallycoordinated Fe3* is proportion- drallycoordinated cations is slightlyless than 9.@ in all ally splitbetween @e + Al) andSi. Note that Si is slightly samplesbut one,whereas the sums ofoctahedrally coordi- lessthan 5.00 in mostsamples, and the total population of natedcations are slightly higher than 2.@ in mostsamples. tetrahedrallycoordinated cations is slightlyless th,n 9.00 Samplesfor whichlFe wasdetermined as FeO only are in all samplesbut one. markedby vectorspointing in thedirection ofthe shift that wouldbe generatedby convertingsome Fe to trivalent stateand tetrahedral coordination: note that all but oneof thesesamples have octahedral-site occupancy greater fhan the tetrahedralsites, up to 0.036 atomsout of the total 2.@,and all but onehave tetrahedral-site occqrancy less of 9.000. This deficit would be lower in samplesfor than9.00. However, note the "errof'bars added to empha- which Fe& was not determined.Assuming all the Fe as sizethe very small deviation from ideality in mostsamples. divalent would increasethe total occupancyof octahe- dra above2.00. It mustbe notedthat a similar deficit in the I site is shown by the Arge,ntiniansamples of (1979), Schreyeret al. for which Fek was determined. environmentsin which light-elementconcentations are Boron and beryllium are present in insignificant such as ordinary granites(Schrcyer et aL arnountsonly. Appreciablecontents of B**, substitut- 1979, Hawthorne et al. 1993), metamorphicrocls in ing for AF andcompensated by cbannelNa+, were found general (as reviewed by Hawthome 1995) and those (Cemf in severaloccurrences of cordierite & Povondra equilibrated in the granulite facies in particular (e.9., L966,L967,Piyar et al. 1968,Povondra & Cech 1978, Gtew et al. 1990, L991, 1995). Selkregg& Bloss 1980,Povondra et aI.1984, Odandi & Pezzolta 1995, et al. L979). However, B The presentcase serves as yet anotherexample ofthe Schreyer - is found in negligible amounts only in minerals of abovefeature. The Dolnl Bory HatEpegmatites show the cordierite group, although it was rarely sought a poorly evolved geochemicalsignature: the rare-earth (cf Grew et aL l99O, 1991,1995). elements,Ti, B, W, M>Ta and P are dominant in the accessoryminerals (Standk1954, L99l). The only expressionof Li was identified there in Geochemicalsignfficance of light elementsin mineralogical rare primary triphylite, and in equally scarce rock-formingminerals extremely secondarycookeite (J. StanEkand P. Povondr4 pers. cornnr., 1993). However, relatively large quantitiesof The results of our re-examination of sekaninaite Li must havebeen incorporated into sekaninaite,which emphasizeagain the fundarnentalneed for analysesof was rafher abundantin someof tle pegmatiteveins, in mineralsfor light elements,even in environmentsthat crystalsup to 70 cm long (Standk1954). arenot particularly suggestiveof the potentialpresence of such elements in significant quantities. Minerals Underconditions of high activity of Na, mineralsof never suspectedto contain, and never analyzedfor, the cordierite group evidently are good sinks for Li, light elementsare recognizedtoday as their carriers even if this elementis presentin negligible concentra- in increasingnumbers. This is particularly significantin tion only in the parent medium-Because of the close r72 TIIE CANADIAN MINERALOGIST structuralsimilaligy to beryl, Cs also may be expected Drncer, J.F. & Jorwsron, I.H. (1974): Single-crystal57Fe to enter the channels of the cordierite framework. Mdssbauerstudies of the site positionsin cordierite.A6t Cordierite is the only magmatic mineral in granitic J. Chem.n,249-258. rocks in which Cs behavescompatibly (London 1995). Concenfrationsof Li and Cs should be examinedin GnrsBnRG,A.I. & Sravnov, O.D. (1961):On the contentof (in cordieritefrom highly fractionatedpegmatites rare elementsin cordierite. GeoHrim-1961, 183-186 andfrom Russ.). Li,Rb,Cs-enrichedmetasomatic assemblages dispersed in their host rocks. Gomuar, D.S., Rossuan, G.R. & DonasE' WA. (1977): Channelconstituents in cordierite.Ara Mineral, 62. LL4+ ACKNOWLEDGEMENTS 1t57. GoRDtrl,o,C. E., ScIrREyB"W., Wmonqc, G. & Asnauau, Ii Our thanks are due to Drs. A. Pfeiferovd and (1985):Lithium in NaBe cordieritesfrom El Peft6lr,Sierra M. Nov6k, and to Dr. J. Standkfor the loan of sekani- deC6rdob4 Argerrina. Cotrib, MineraLPetrol. N, 93-1,01. naite specimensfrom the collections of the Moravian Museum and Masaryk University, respectively. The Gnew, E.S., CHRNosKy,J.V., WRDD.rc,G., ASRAHATaK., study was supportedby NSERCMajor Installationand MAReuu, N. & HnrnroR}{E,J.R. (1990): Chemistry of ResearchGrants to P.C. Dr. T.S. Ercit (Canadian and associatedminerals, a wet chemical,ion microprobe,and X-ray study emphasi"jngLi, Be, B Museum of provided and F Nature, Ottawa) valuableadvice contents.J. Petrol, 31, 1025-1070. in the initial stagesof EMPA analysis. 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