American Mineralogist, Volume 7 I, pages I I 29- I I 34, I 986

Li, Be, B, and Sr in and paragonitefrom Antarctica

Eow,q.RDS. Gnrw Department of Geological Sciences,University of Maine, Orono, Maine 04469, U.S.A. Jlnnns R. HrNrnonNB Department of Geology, Central Washington University, Ellensburg,Washington 98926, U.S.A. Nrcrror.,ls M.lneunz AerospaceCorporation, P.O. Box 92957,[-os Angeles,California,90009 U.S.A.

Ansrucr Peraluminous margarite and of retrograde origin in a staurolite- and corun- dum-bearing -tourmaline--chlorite schist from Mount Bernstein, northern Victoria Land, Antarctica,contain 0.17 and 0. 18 wto/oLirO, 0.05 and 0.0040/oBeO,0.02 and 0.310/oBaO, and 0.26 and, 1.30loSrO, respectively,by -microprobe analysis (esti- mated accuracy:+20o/o).In addition, only 0.010/oF and 0.02-0.030/oBrO3 and no Rb were found with the ion microprobe. This is the first report of significant amounts of Li and Sr in paragonite. The unusual compositions of the paragonite and margarite are attributed to their ability to incorporate Li releasedfrom breakdown of lithian staurolite and Sr made available during a retrograde metamorphic stagein a silica-undersaturated rock. Their low BrO, contents are attributed to the inability of the structure to accommodate the small rvB ion in the tetrahedral sheeteven in a B-enriched host rock.

INrnooucrroN andcorundum at 300-370"C and 3-5 kbarduringthelate Since the advent of the electron microprobe, the light- (retrograde)stage in the metamorphic cycle (Grew and element contents (Z < 9) of rock-forming minerals h-ave Sandiford' 1984, 1985)' been largely neglected in rnetamorphic petrology. For the MrcnopnonE ANALysrs dioctahedral , this could be a serious oversight, be- Electron-microprobeanalyses of l0 major elementsin mar- causeLi can play an important role in thesemic:11'.-: coviteand margarire areknown toincorporat. d;t#H; ffi': I;il;:i*ffi';,ft$:'fii:,;XT: ir*ffLfi.::Xt: amounts of Li in the appropriate environment, as re- tai"eAattfren"frr-UniversitiitBochum,andof13majorelements viewed by Cern!'and Burt (1984)and Gt'ggenheim(1984). i' biotiteat theUniversity of Melbourneand University of Cal- In this communication, we report electron- and ion-mi- ifornia,I-os Angeles (Table 1; detailsof the analyticalmethods croprobe analysesof a margarite and a paragonite con- givenin Grewand Sandiford,1984, and Grew,1980). taining significant Li, Sr, and Be. As far as we are aware, Secondaryion spectrain the massrange I to 150 (H through this is the first report of paragonite containing more than Nd) from one flakeeach of the margariteand paragoniteas well tracesof Li and one ofthe few-reportsofa mici containing as from the.four standardslisted in Table2, werescanned and massanalyzer (turrrl) at more than traces of Sr. We also discuss possible conl recordedwith an .c.nl-ion-microprobe theAerospaceCorporationinlosAngeles(methodofGrewand straints on the incorporation of B in micas. we studiedlithian and srrontian paragonite and mar- 11il|,!Tilti"tj);"ffiil:'*#?;ff.tffit:fj};.1?X; garite occurring as a few flakesin a staurolite- and corun- tuti retvon" tirn. duringihecourse ofrhe dayJongsession. dum-bearing talc + phlogopite + chlorite + tourmaline Raw ruvr count ratios,except for Sr, were correctedwith schistfrom Mount Bernstein(71"37'S, 163'07'E) in north- mineralstandards of knowncomposition (Table 2): spodumene ?Li./xSi, '3EBt2ESi ern Victoria land, Antarctica (Grew and Sandiford, 1984). for for and "F/28Si,grandidierite for Margarite forms flakes 0.05-0.25 mm acrossin a sericitic 'rB/2ESi,and surinamite for 'Be/28Si(working-curve approach of aggregatesurrounded by tourmaline. Pumpellyite, chlo- Grewand Hinthorne,1983). Positivety charged secondary riie, and relict staurolite are also present inihe aggregate. were measuredin all cases.In applying standardsof differing from the unknowns'we have Paragoniteoccurs as two contiguousflakes 0.2 mil aJros, crystaltT:1t* and composition matrix hasa relativelvminor effecton the count surrounded by tourmaline and 0. I mm distant ft;; ;;: T:,1T"^111the rundum,which ispartia[y enveroped ioa se,iciiic ffi iilii;,Tlilf"lffif,fflfr:Ti;',rj#T*:HjtSnH:; gate. The analyzed paragonite and margarite are only 2 fo, data from the rvr,an-The grandidieriteB/Si and surinamite mm apart, but are separatedby tourmaline and thus may Be/Siatom ratios were assumed to be I and0.309, respectively, not have equilibrated with one another. The margarite on the basisof crystal-structurerefinements (Stephenson and and paragoniteformed from the breakdown of staurolite Moore, 1968;Moore and Araki, 1983).The LilSi ratio in the 0003404x/86/0910-l 129$02.00 1129 I 130 GREW ET AL.: Li, Be, B, AND STIN MARGARITE AND PARAGONITE

Table1. Compositionsof spodumeneand biotite standards Table 2. |MMAcount ratiosfor mineralstandards andof paragoniteand margarite in sampleno. 4017E ldeal Mea- Spodumene Biotite- Paragonite Margarite'- tiilrA or ana- sured Predicted MS2975A 2045G 4017E 4017E lsotope Standard Count lyzed sensitiv- sensitivity ratio mineral ratio ratio ity ratio ratio Electron-microprobeanalysis (weight percent) 1'B/'zosi Grandidieritet 0.344 1.00 0.344 0.355 sio, 64.17 38.34 4173 30.12 eBe/'z8si 0.286 0.309 0.926 1.36 <0.01 4.86 0.02 0.24 Surinamitet. Tio, 7lil28si Spodumenet 1.339 0.49s 2.704 2.98 Alro3 49.46 27.32 13.25 41.24 lsBa/r8si Biotite+ 0.0295 0.00928 3.179 3.36 Cr.O" <0.02 0.'t2 <0.02 0.10 teF/26si Biotitet 0.0146 0.282 0.0518 0.017$ FeO 0.02 6.14 0.27 0.33 MnO 0.07 0.03 <0.01 <0.01 * As inclusions in kornerupine from Port Shepstone, South Africa. Mgo <0.01 20.96 0.27 0.69 Sample 8M1940,39,British Museum (NaturalHistory) See de Villiers CaO <0.01 b.d. 1.00 10.95 (1940). Na.O 0.15 0.12 6.66 166 .. From pegmatite, Enderby Land, Antarctica. Sample 22928' Grew =0.01 K"O 10.24 0.62 0.03 (1981 ) BaO 0.91 t From pegmatite, Tin Mountain mine, near Custer, South Dakota. r 3.41 Samole MS2975A of the museum in the Departmentof Earth and Space 0.02 Sciences,University of California,Los Angeles. From a sapphirine-garnetrock, Sample 2045G, Gage Ridge, Enderby lon-microprobeanalyses (weight percent) + Land, Antarctica (see Grew, 1983). Liro (7.8e) 0.03 0.18 0.17 $ Measuredvalue (see text). BeO b.d. b.d. 0.007 0.05 B.o. b.d. 0.01 0.031 0.02 SrO b.d. trace 1.3 0.26 BaO b.d. (0.91)+ 0.31 0.02 F b.d. (3.41)f 0.01 0.01 For Sr,the measured88Sr/2ESi ion ratio wasdivided by the relative Total 99.62 98.44 93.65 94.11 sensitiyity factor of 3.7 (computed from the local thermal equi- -o:F,cl 1.63 librium (LTE) model of Andersen and Hinthorne, 1973). This Total 96.81 correction appearsreasonable, given the closecorrespondence of Cations the measuredand theoreticalBa sensitivity factors(Table 2), and Si 1.998 5.584 5.521 4.053 the nearly identical behavior ofBa and Sr during ion bombard- AI 1.003 2.274 2.470 3.927 ment. 0.007 0.004 B 0.000 0.004 Of the elementssought in this study, namely Li, Be, B, F, Sr, Be 0.000 0.000 0.002 0.016 and Ba, only Be analysis is complicated by interferenceat the Total 3.001 7.862 8.000 8.000 concentrationsthat we found ofthese elements.Triply charged AI 0.000 3.961 3.917 27Alinterferes vrith the eBesignal at mass 9. In order to correct Ti 0.000 0.532 0.002 0.024 0.000 0.014 0.000 0.011 for the contribution of triply charged2T41, we estimatedthe ratio Fe 0.001 0.748 0.030 0.037 of triply charged27Al at mass 9 to singly charged 27Al at mass Mn 0.002 0.004 0.000 0.000 27 tobe 5 x 10-s from counts obtained on minerals containing 4.550 Mg 0.000 0.053 0.138 negligibleBe, suchas sillimanite and andalusitein Be-poor rocks Li 0.989 0.018 0.094 0.092 and grandidierite. We calculated the contribution of eBe to the Total 5.866 4.140 4.219 counts at mass 9 in Be-bearingminerals by deducting 5 x l0-s Ca 0.000 0.000 0.142 1.579 times the counts at mass 27. Sr 0.000 0.099 0.021 Ba 0.000 0.052 0.016 0.001 In contrast to most positively charged secondaryions, F has Na 0.009 0.034 1.709 0.433 such a high first ionization potential that only a small fraction K 0.000 1.902 0.105 0.005 of F ions are emitted as "thermal" ions, and thus, F sensitivity Total 1.001 1.988 2.071 2.039 cannot be predicted by the LTE model. The relative sensitivity Total (F/Si) value of 0.0 17 listed in Table 2 for F was determined from cations 4.O02 15.716 14.211 14.258 a working curve relating F/Si ratios obtained by classical chem- F 0.000 1.573 0.004 0.003 ical techniqueswith thosemeasured on the nvlve (Hinthorne and vl 0.004 Andersen,1975). Oxygens 22 22 22 s.s$ In sum, the weight percent of a given oxide was calculated by /Vote.'All Fe as FeO. Dash-not analyzed or not calculated.In paren- the following equation, for example, for LirO: theses-calculated or assumed values in the standards. b.d.-below de- tection. 'Electron-microprobe 2Li,O:SiO, ?2{!11':'=: analysis done at the University of Melbourne " 60.0843 Si 2.704 and UCLA, remainderat the Ruhr-UniversitatBochum. " Electron-microprobedata from Grew and Sandiford (1984, Table 2, and weight percent F, by margariteA) t Possiblecontribution from tourmaline(see text). 18.9984 F l Not includedin the analyticaltotal. ts:5ru2 t t t + 60.0g43 s o.osta' $ For Al and Si only. where SiO, : weight percentfrom electron-microprobeanalysis, LVSi and F/Si : count ratios correctedfor background,and the spodumene standard was calculated from the electron-micro- remaining numbers are the atomic weights and the measured probe analysisassuming a formula (Li,Na,Mn,Fe)AlSirOu(Table sensitivity ratios from Table 2. For margarite,the following val- l). The BalSi and F/Si ratios in the biotite standard were cal- ues were measured(in counts per second corrected for a back- culateddirectly from the electron-microprobeanalysis (Table l). groundof 3 c.p.s.):LilSi : 12 438/2Ol60 I and 12 352/200538 GREW ET AL.: Li, Be, B, AND STIN MARGARITE AND PARAGONITE I 131

(repeatedmeasurements) and F/Si :9/201601, which were en- 4) found that IvAl contentsrarely exceededthe ideal value tered into the above equations to obtain the values listed in of 2 atoms per (20O + 4OH). The paragonitein sample Table l. 4017E is unique in its substantial excessof I'Al relative Estimatedprecision ofthe ruue data (basedon our experience to the amount of Ca. usingthe rvva for similar analyseson several is occasions) about In order to clarify possible substitutions leading to the +200loof the given value for Ba (in paragonite),Li, and Sr, for peraluminousmargarite and paragonitecompositions, we which the observed intensity exceeded1000 counts (counting time : l0 s). Precisionis poorer than +200/ofor intensitiesbelow have compiled in Table 3 a set of mica endmembercom- this, asfor Ba (in margarite),Be, and B. For example,LirO values ponents that appear most appropriate for this task. In on biotite 2045G from two ditrerentsessions on the rnaruedifered addition, we give in Table 3 the exchangeoperators that by less than 30/0,whereas BrO, values differed by 300/0.Values will producethese endmember components when applied given in Table I for biotite 2045G are a weighted average of two to a startingcomposition of, in this case,paragonite (meth- rvva sessionsfor Li and three sessionsfor B; weightingwas based od of Thompson, 1982).The only component not in- on the observedion intensity for eachsession, assuming that the volving Li, Be, Sr, and Ba is a hypothetical endmember higher count rates prowided better results. For comparison, we Na,MgAlo(Si4Al4)O,o(OH)oin which five of the six octa- note that Grew and Hinthorne (1983) reported spreadsof l5 to hedral sites per formula unit are occupied. Kienast and 20o/oof the measuredvalues for BrO, in two sillimanites (count Velde(1968) and Chopin(1977) proposed this component ratesof at least 100 c.p.s.),and 50/ofor BrO, in two kornerupines (count to explain compositional variations in paragonite and ratesofat least 1000c.p.s.). IVAI The good agr'eementbetween the measuredand predicted B/Si margarite, respectively.However, not all the excess sensitivityratios (Table 2) confirms Hinthorne and Ribbe's (1974) in our micas can be explained through this substitution. use of the predicted ratios to measurethe B contents of chon- If Li, Be, Sr, and Ba are assumedto be incorporated as drodite. We note that Guggenheimet al. (1983, p. 253) also used ephesite,bityite, and the hypothetical Sr-Al and Ba-Al spodumeneas a standard for measuring Li in the Li-Be mica endmember micas, all but about 0. I and 0.2 atoms per bityite and reported that their ion-microprobe data "confirm" formula unit of the excessAl are accountedfor in parag- earlier wet-chemicaland spectroscopicdata. onite and margarite, respectively (Table 3). Further, the calculatedoctahedral occupancies of 4. I 40 and 4.219 for IoN-nnrcnopRoBE RESULTS paragoniteand margarite exceedthe ideal value of 4 for Both the margarite and paragonite contain significant dioctahedral mica by the amount of Li and Mg present Li and Sr and measurable amounts of Be (Table l). A (Table l). We have selected bityite, Ca'LirAlo small amount of Ba is present in the paragonite, but no (AlrBerSio)Oro(OH)o,and ephesite,Narl-irAlo(Al4sio)Oro Rb was detected in the scans of either mica (detectability (OH)., as endmembers, because available data suggest limit for Rb is <50 ppm in the qualitative mass scans). some degreeof solid solution between these Li-bearing The margarite and paragonite in 4017E do not contain micas and the Li-free margarite and paragonite. For ex- significant F or B (Table l). The low F contents are not ample, the chemical data of Gallagherand Hawkes (1966) unexpected. F was not detected in tourmaline, which was and the crystal-structurerefinement of Lin and Guggen- analyzed at one spot in this sample with the rvva during heim (1983) imply that solid solution betweenbityite and a previous session (F detection limit is about 0.05 wto/o). margaritemay be closeto complete.The extent ofephesite On the other hand, the low B contents of the margarite solid solution in margarite is lesswell known. Margarites and paragonite suggest that they incorporate little B in a containing up to 0.29 wto/oLirO but lessthan 0.010/oBeO B-rich environment (cf. Harder, 1959, who reported 0.03- (Schalleret al., 1967)may have some 7-8 molo/oephesite. 0.07 wto/oBrO, in paragonite). The 0.030/oBrO, reported Ephesitesolid solution with paragonitemay be more ex- for paragonite in Table 1 may in part be due to a hidden tensive,for Drits and Semenov(1975) reported a mica tourmaline impurity or to interference from the surround- containing 67 molo/oephesite, 25o/o paragonile, 60/omar- ing tourmaline, for no B was detected in the element scan. garite, and 2olomuscovite. We selectedthe Sr and Ba di- octahedralendmembers because the most appropriate ex- Drscussror',1 changelocation for Sr and Ba substitution is the interlayer A discussion of the light-element and Sr contents of site. Sr commonly substitutesfor Ca and K. In calculating micas involves two considerations:(l) the effect of these a formula for "sodian margarite" containing 0.62 wto/oSr elementson the major-elementcompositions of the micas reported by Afanasyev and Aydinyan (1952), Schaller et and (2) the crystallographic and environmental con- aI. (1967) assumedthat the resulting 0.06 Sr per formula straints on incorporation of theseelements into the mica unit substitutedfor Ca. Ba substitutesfor K in structure. (e.9.,l7o/o in Dunn, 1984;22o/o in Dymek et al., 1983). The unusual composition of the Antarctic margarite Li, Be, and Sr in margarite and paragonite and paragonitecan be attributed not only to their ability A characteristicfeature of margarite compositions is an to incorporate Li, Be, and Sr, but also to local enrichment excessof IvAl relative to an ideal stoichiometric mixture of Li, Be, and Sr during the retrogrademetamorphic stage. of the major endmember compositions of margarite, pa- Li probably originated from breakdown ofnearby stau- ragonite, and (Frey et al., 1982, Fig. 6). In his rolite (grain 2, Table l, Grew and Sandiford, 1984),which review of paragonite compositions, Guidotti (1984, Fig. contains about 0.2 wto/oLirO (Ivrua analysis,this study). tt32 GREWET AL.: Li, Be,B, AND STIN MARGARITE AND PARAGONITE

Table3. Hypotheticalcomponents and substitution operations in margariteand paragonite(in termsof cationsper 20O + 4OH)

Component Percentagein Cation composition' Operation Margarite Paragonite

Paragonite NarAll(AbSi6) 3 77 Margarite CarAlo(A14Sin) CaAlNa-,Si-, 77 Ephesite NarLirAll(Al4Si4) LiAtsi_1 4 NarMgAl4(Al45i4) MgAbSi-, 14 Bityite CarLirAliAlrBerSi4) CaLiBeNa-,Si-, 1 0 SrrAl.(Al4Si4) SrAlNa-,Si-, 1 BarAl4(Al4Si4) BaAlNa isi-1 0 1 . K is includedwith Na. and Fe with octahedralAl

The source of Be is problematic, as no Be was detected as much as 0. l-0.6 wto/oBrOr, whereasmargarite, parag- with the rurvrain staurolite or tourmaline. The source of onite, biotite, , and most muscovites contain Sr may be the same as that of Ca. Grew and Sandiford 0.loloor less.More recent data on micas associatedwith (1984) suggestedthe following possiblesources for Ca: (l) borosilicate minerals are further evidence that micas in calcic plagioclasethat formed early in the metamorphic generalincorporate little B, even when B is available. One history and subsequentlywas replaced by albite, (2) so- example is biotite formed at temperaturesnear 700'C in lutions percolatingthrough the rock during the late stage, associationwith B-bearing kornerupine, an Al-rich Mg- or (3) tourmaline. An analysisat one spot in the rim of a Fe silicate. Of six such we analyzed,five contain tourmaline prism in sample 4017E (electron-microprobe lessB,O, than the biotite in sample2045G (0.010/o BrOr, analysis given in Table 2, Grew and Sandiford, 1984) Table l), a rock lacking borosilicates,and the sixth con- yields roughly 0.05 wto/oSrO (estimatedby applying the tains roughly the sameamount as biotite 2045G. Another sensitivity factor given in Table 2 to rvrrla data from a example is polylithionite [KrAlrLio(Si8Or0)F4],associated previous session). with reedmergnerite(NaBSiO') and other borosilicates Another factor leading to Li and Sr enrichment in the in alkali pegmatitesfrom the southern Tian-Shan Moun- margariteand paragonitemay be the silica-undersaturated tains (USSR). Dusmatov et al. (1972) reported BrO, con- environment of sample 4017E. Li incorporation as an tentsof 0.064.100/o(average 0.08), and W. Schreyerand ephesiticcomponent in paragoniteand margarite may be G. Werding obtained 0.130/oBrO3 (unpub. data) on poly- enhancedin -freerocks becauseephesite is not sta- lithionite in a specimen from the Fersman Museum of ble in the presenceof quartz (Chatterjee and Warhus, reedmergnerite-quartzrock from the samealkali intrusive 1984). The Antarctic sample illustrates that more exten- complex. The low B contentsof paragoniteand margarite sive compositional variation in micas, particularly sub- in 40178 imply that thesetwo dioctahedral micas do not stitutions involving Li and Sr, is possible in the appro- incorporate B in a B-rich environment. priate chemical environment. Staurolite in which Li is The mechanism limiting B substitution in micas re- sought analytically generally is found to contain Li (see mains poorly understood. Hazen and Wones (1972) re- referencescited in Grew and Sandiford, 1984;also Dutrow ported synthesizing at 720C a mica of composition et al., 1984;and unpub. data reportedby Hinthorne,197 5), KrMgu(BrSi6OroXOH)'.However, accordingto their and consequently,secondary mica forming from staurolite equations for a geometric fit of the tetrahedral and octa- may incorporate Li. Moreover, limited Li incorporated hedralsheets (see Hazen and Wones, 1978,p. 886),such in margarite as ephesite in conjunction with increasing a composition is impossible. The BSi, tetrahedral sheet octahedraloccupancy through the substitution MgAlrSi_, is too small to match the Mg octahedral sheet. Given a (Table 3) may explain the margarite compositions with mean tetrahedral metal-oxygen distance (d,) of 1.58 A excesslvAldiscussed by Frey et al. (1982). (for BSir) and a mean octahedral metakxygen distance (d") of 2.06 A (for Mg), the ratio d,/d" of 1.30 falls outside B in micas the rangeof 1.235-1.275 that Hazen and Wones (1978) The limited extent of Li, Be, and Sr substitution in specified for trioctahedral-mica stability. Robert (1981, natural paragoniteand margarite may be controlled large- p. 46), who reachedthe same conclusion, proposed that ly by the availability of theseelements, which are present incorporation of I"Mg will enlarge the tetrahedral sheet in low concentrationsin most rocks (e.g., Sr in Guggen- sufficiently to match the octahedral sheet.Robert (1981) heim, 1984, p. 6l). Furthermore,there are no obvious reported infrared evidencefor IvMg in a synthetic B-bear- crystallochemical constraints on substitutions involving ing "micaceous phase" that he obtained during his un- Li, Be, and Sr. However, micas rarely incorporate much successfulattempts to synthesizea mica of composition B, even in B-rich environments. Harder (1959) and Of- KrM*(BrSiuOroXOH)0. However, the mechanism pro- tedal (1964) reported that a few muscovites incorporate posed by Robert (1981) may not be operative in meta- GREW ET AL.: Li, Be, B, AND STIN MARGARITE AND PARAGONITE l 133 morphic trioctahedral micas, as these micas generally con- in staurolite: Its petrologic significance.Geological Society of tain enough Al to fill the tetrahedral sites. An exception America Abstracts with Programs, 16, 49'7. is the biotite 2045G, in which Si + Al + B : 7.862. Dymek, R.F., Boak,J.L., and Kerr, M.T. (1983)Green micas in the Archaean Isua and Malene supracrustalrocks, Southern Because the ideal value is 8, addition of I"Mg could make West Greenland, and the occurrence of a barian-chromian up the difference. Nonetheless, the B content of the mica muscovite.Gronlands GeologiskeUndersogelse Rapport, I 12, is low. In summary, incorporation of B in micas, diocla- 7r-82. hedral as well as trioctahedral, is most likely restricted by Frey, M., Bucher,K., Frank, E., and Schwander,H. (1982) Mar- garite Alps. Mineralogische Pe- the mismatch of a B-bearing tetrahedral sheet and the in the Central Schweizerische trographischeMitteilungen, 62, 2l-45. probably octahedral sheet; the influence oftemperature is Gallagher, M.J., and Hawkes, J.R. (1966) VIL Beryllium min- much subordinate. Even a few scattered B-bearing tetra- erals from Rhodesia and Uganda. Geological Survey ofGreat hedra must create enough distortions in the mica structure Britain Bulletin , 25, 59-7 5. to destabilize it, therefore limiting the amount of B that Grew, E.S.(1980) Sapphirine + quartz associationfrom Archean rocks in Enderby Land, Antarctica. American Mineralogist, can be incorporated. 65, 821-836. -(1981) Surinamite,taaffeite, and berylian sapphirinefrom AcrNowr,rocMENTS pegmatitesin granulite-faciesrocks ofCasey Bay, Enderby I^and, We thank K. Abraham for assistancewith operation of the Antarctica. American Mineralogist, 66, 1022-1033. electron-microprobefacility at the Ruhr-Universitiit Bochum, -(1983) Sapphirine-garnetand associatedparageneses in and W. Schreyerand G. Werding for the BrO, analysisof poly- Antarctica. In R.L. Oliver et al., Eds. Antarctic Earth science, lithionite. The British Museum (Natural History), the Depart- 40-43. Australian Academy of Science,Canberra. ment of Earth and SpaceSciences, University of California, Los Grew, E.S., and Hinthorne, J.R. (1983) Boron in sillimanite. Angeles,and the Fersman Mineralogical Museum of the USSR Science,221,547-549. Academy of Sciencesin Moscow are thanked for samples.Fi- Grew, E.S.,and Sandiford, Michael. (1984) A staurolite-talcas- nancial support from the Alexander von Humboldt-Stiftung semblagein tourmaline-phlogopite-chloriteschist from north- (Bonn) and U.S. National ScienceFoundation Grant DPP84- ern Victoria Land, Antarctica, and its petrogenetic significance. 14014to the University of Maine at Orono, and DPP 80-1952'1 Contributions to Mineralogy and Petrology, 87,337-350. to the University of California, Los Angeles, is gratefully ac- - (1985) Staurolite in a garnet-hornblende-biotite schist knowledged.The thoughtful comments of S. W. Bailey, N. D. from the Ianterman Range, northern Victoria Land, Antarc- Chatte{ee, P. C. Grew, S. Guggenheim,C. V. Guidotti, R. M. tica. NeuesJahrbuch fiir Mineralogie Monatshefte, 1985, 396- Hazen, J. M. fuce, and Ian Steeleon earlier drafts of the manu- 410. script are much appreciated. Guggenheim,Stephen. (1984) The brittle micas. Mineralogical Societyof America Reviews in Mineralogy, 13, 61-104. 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Mathematisch-PhysikalischeKlasse, 67 -122. granite pegmatites.Mineralogical Societyof America Reviews Hazen,R.M., and Wones,D.R. (1972)The etrectof cation sub- in Mineralogy, 13, 257-297. stitutions on the physical properties of trioctahedral micas. Chatterjee, N.D., and Warhus, Udo. (1984) Ephesite, American Mineralogist, 57, lO3-129. Na(LiAl,)[Al,Si,O,oXOH)r: II. Thermodynamic analysisof its -(1978) Predicted and observed compositional limits of stability and compatibility relations, and its geologicaloccur- trioctahedral micas. American Mineralogist, 63, 885-892. rences.Contributions to Mineralogy and Petrology,85, 8G-84. Hinthorne, J.R. (1975) Applications of the ion microprobe in Chopin, Christian. (1977\ Une paragendsed margarite en do- mineralogy.(abstr.) EOS (American GeophysicalUnion Trans- maine m6tamorphique de haute pression-bassetemp6rature actions),56,1083. (massif du Grand Paradis,Alpes frangaises).Comptes Rendues Hinthorne, J.R., and Andersen, C.A. 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