ffiian"Mineralogist Vol. 14, pp. 12O-126(1976)
AGRELLITE,A NEW ROCK.FORMINGMINERAT IN REGIONATLY METAMORPHOSEDAGPAITIC ALKALIC ROGKS
J. GITTINS Departmentof Geology, University of Toronto, Toronto, CanadaMsS lAI
M. G. BOWN Department ol Mineralogy and Petrology, ()niversity of Cambridge, Cambridge, England CB2 3EW
D. STURMAN Departmentol Mineralogyand Geology, Royal Ontario Museum,Toronto, CanadaM5S 2C6
ABSTRAcT indicates that the mineral is triclinic: the true cell has a 7,773, b 18.942, c 6.984,{,
Elle form descristaux de duret65% de quelquesmm Long. 45o47'49uN, and it is in this complex a 100mmde long, qui passentdu blanc au glis ou au that agrellite occurs. Type specimens of agrellite blanc verdntre, ont un 6clat nacr6 sur les clivages: are preserved in the collections of the University {rlo} et lii0}, excellents;{0101. indjstint. Optique- of ioronto, Department of Geology @etrology ment elle est biaxe nfuative, 2V 47', no 1.567,np noyal Ontario Museum; Smithso- plan Colection): r.579, n1 r'581' des axes optiques voisin of Mineialogy (010). La composition chimique pourcentages{;( 1ld "i*-ir.iiiii,i;;;D"p;;ent cambridge;- British poids est sio2 58.83,Tioz 0.01, Alror 0.r0, Fer6, Petrology, -!-niversity-.of b.rr, VinO O-ZS,CaO 25:20, S;O O.rO,SuO Ob6; Museum of Natural History; National Museum MgO0.02,ZrOz0.t8,TR3.84,NarO7.9b, KzO0.22', of Canada;Geological Survey of Canada;Insti- HrO + 0.4, F 4.45, total 102.23- (O : F) 1.87, tute for the Mineralogy, Geochemistry and total 100.36.Les terresrares sont: CeOz1.13, YzOg Crvstal Chemistrv of the Rare Elements, Mos- 1.07,LazOa 0.54, PrzOg0.10, NdzOa 0.41, SmzOa .o*. USSn. 0.12,Eu2O3 0.02, Gdzos 0.15,Dyzoe 0.14,Horoa 0.03, ErzOg 0.07, TmzOa 0.01, YbzOa0.04, LuzOg 0.01.Formule calcul6e : (Naa.ooKo.oz)(Caz.3o?Ro.az) (Mn, Fe, Sr, Ba, M.g, Zr)o.u (Sira.orAlo.os)Ogs.zo (Fs.zaOHo.rr)ou (Na, K)r.oa (Ca,?R,elc.)r.saSia.er On.sa(F, OH)r.rr, Z : 4, densit6calculfu 2.887, GeNsneL Gnorocv mesurEe2.902. L'6tude par rayons X d'un cristal min6ral maille unique indique un triclinique; la waie The complex is poorly exposed in forested possddeles d.imensionsa 7.773, b L8.g42,c 6.9&lli, country. The commonest rocks are banded glL.sLs, cuS.148", 0 116.&1',? 94.145', l/ avecr6se{ru gneissescomposed of albite, otisl6sline, alkalic P. 11existe une maille double quasi monoclinique,et (arfvedsonite and kataphorite), aegi- plus pseudo- amphibole les rdflexions les fortes soulignent cette and eudialyte. Eudialyte is sym6trique presqueparfaite. Les raies de poudre les rini-augite, nepheline 10 mm thick' plus fortes ont 6t6 mesur6esaux esoacementssui- concentrated in thin layers up to vants:3.44(F) (200,I50), 3.33(F) (ZZO),e.rg (nF) Calcite and fluorite are ubiquitous accessories Within (150,051),3.r4 (FF) (220,060,202,002),2.57 (F) and locally assumeessential proportions. carbonate rocks of un- €5t, TZOI.Le nom honorele Dr Stuart O. Agrell du the gneissesare minor D6partement de min6ralogie et de p6trologie de certain character composed of calcite, diopside, fUniversit6 de Cambridge,en Angleterre. phlogopite, clinohumite, norbergite and zircori. bthei gneissesare rich in biotite. Most of the par journal) (Traduit le gneissei contain the rarer minerals hiortdahlite' other members of the wiihlerite group, mosan- drite, miserite, britholite, vlasovite, the new unnamed mineral CaZtSraOr,accessory galena, INTRoDUcTIoN and several other as yet unidentified minerals. Some gneissesare composedof more than seven- pods Agpaitic alkalic rocks are relatively uncom- ty percent of agrellite. Pegmatitic -and mon and in every casethey are characterizedby lensis within the gneissesare composed of these a wealth of unusual minerals. Among the bet- minerals and agrellite, but their proportions vary ter known occurrences are the plutonic intru- considerably.,{ common type of pegmatitic lens tions of Ilimaussaq in Greenland and Lovozero consists of'agrellite in interlocking crystals up in the U.S.S.R. All the examples describeduntil to 1O0 mm in length together with eudialyte up recently have been unmetamorphosed igneous to 50 mm across, microcline, mosandrite and a rocks but two examplesare now known in Can- small amount of amphibole. Other types are ada where such rocks have undergone reglonal primarily eudialyte with amphibole and mosan- metamorphism in the amphibolite facies. The drite, oi eudialyte with mosandrite and vlaso- first of these is a group called the Red Wine vite, the latter in crystals up to 100 mm in size. Complexes centred at Lat. 62'3OW, Long. Accounts of vlasovite, the new mineral CaZr- 54o1yN, in central Labrador (Currie et al. SirOr, and hiortdahlite from Kipawa are given 1975), where the rocks have been largely trans- by Gittins et al. (1973) and Aarden & Gitlins formed into gneissescharacterized by an abun- (i974>. The gneissesare complexly folded but dance of arfvedsonite, jadeitic pyroxene (up to the pegrnatitic pods show no evidence of de- 70 percent jadeite), titanian ferro-omphacite, formation and frequently contain minerals dis- titanian aegirine, aenigmatite and varying playing euhedral character. It seemsvery likely amounts of albite, microcline and nepheline.The ihai partial melting has occurred during regional second occurrence is the Kipawa Complex on metamorphism and that the pegmatitic rocks the Kipawa River, Villedieu Township, T6mis- represent the crystallization of the resultant caming County, Qu6bec,at Lat. 78o2y31' W, liquid. Intergrowths of calcite and fluorite have r22 THE CANADIAN MINERALOGIST
TABTE1. ANALYSESOT ACRELLITE .counteredwith SiOz, ALOg and the rare earths. 12 34 5 Becauseof high F content, silica tends to vora- si02 57,79 57.90 58.83 58.B3 tilize as SiFa during the initial fusion of the Ti02 0.01 0.01 Ce02 l.l3 mineral in NazCOa, and loq/ values always re- sult. 41203 1.32 0.80 0.10 0.10 \zo3 1.07 Accordingly, the SiOz value determinld bv electron microprobe analysis has been accaptea F"203 0.11 x 0.42 * 0.ll * 1a203 0.54 as the most reliable. The classigala.mmonia pre- Mno 0.25 0.20 0.25 Pr203 0. 10 cipitation of the R,Og group is complicated in Cao 25.70 26.43 35.94 ZS.7O Nd203 0.41 the case of agrellite by the presence of the rare 5r0 0.16r * 0.16* * Sm203 0.12 eartls..These are precipitated to varying degrees Bdo 0.06 * * 0.06* * Eu203 0.02 according to the pH of the solution and no ade- quate control possible. llS0 0.02 0.02 Gd203 0.15 is To overcome this dif- ficulty, the rare earths were determined ZrO2 0.1B 0.1B 0v^0. 0.14 as a group by the oxalate precipitation method. Thev RE 2.57 3.84 3.61 3.94 Ho203 0.03 were also determined individually by emission Na20 7.90 7.13 7.90 Er203 0.07 spectroscopy.4lrOr, was determined by electron K20 0.22 0.20 0.22 Tmr0, 0.01 microprobe analysis. ZtOz wus determined by H20f 0.4 0.17 0.4 Yb203 0.04 the mandelic acid method. Fluorine was deter- mined by the F 4.45 + 4.60 4.45 1u203 0.01 method of steam distillation and 'l0l.l4 't02.23 thorium nitrate titration. HgO* is quoted to 101.69 98.48 only one decimal place 0=F l.B7 1.93 r.87 because it is so much less abundant 99.27 99.76 I 00.36 than fluorine that the latter causes interference in the Penfield method. l. Classicalwet chmical analysisi analystJ. Gittins (except for Sr0 and Baods noted below) 2. Classicaimt chemicalanalysisi analystA.ll. Bykova,IlyGRE, An independent analysis by A. W. Bykova l4oscok,.U.S.S.R.(Except for rare earths by spectrographic rethods) was kindly arrangedby E. I. Semenovof IMGRE. 3. Eleciron microprcbeanalysls by E.L. Gasparrini, UnlversJtyof Moscow, U.S.S.R. Toronto Spectrographic analysis of 4. l'4ostprobable compositlon (combined sources) tlo rare earths was also carried out in the same 5. Rareearths by spectrcgraphlcanalyslst analyst L. Loginova, lltlGRE,Moscow. U.S.S,R. institute and the results are given in Table I. A * Total lron expressedas Fe,01 different specimen was used for the Russian r * Analyst: C.0. Ingarells, ir6llmlnary figure only +. Analyst: ,1. Glttins 4.2B, 4.61, Schwarzlopfnlcrcanalytlcal analysis. The calculated mineral formula is Laboratory4.30,4.60 (Nar.ooKo.oz) (Caz.go R Eo.s) (1\In,Fe, Sr,Ba,Mg, _-2.r)o.r e (Si'a.orAlo.oa)Oae.ro (Fa.zaOHo.zr). This may a texture be simplified to identical to that which results from (Na,K)r.oa(Ca,RE, eutectic crystallization elc.)r.etsig.srOe.sa(F,OH) r.rr in the system calcite- and the general fluorite (Gittins formula taken as & Tuttle 1964) and probably NaCazSiaOroF. result from the crystallization of anateciic melts. Whet!91 agrellite is a mineral of primary igneous crystallization that has undergone subsEquent metamorphic recrystallization, or has formed during regional metamorphism, is not known. X-Rav DrrrnecrroN Sruoy
Unit cell and symmetry Cnsrurcer, CotrposrttoH Single crystals of agrellite were examined ini- tially by standard photographic methods on Chemical analyses of agrellite are tabulated oscillation, Weissenbergand precessioncameras. in Table 1. Because of the large size of the The symmetry was established as triclinic" and crystals, concentrates of very high purity ,are approximate unit cell dimensionswere obtained. readily prepared for analysis. Classical wet chem- The cell dimensions were refined by least-squares igal methods were employed'spectrophoiometryfor SiOz,!R.E, CaO, analysis of 2d values obtained for 20 reflections 19, PlO, an{ MgO; for on a Picker automatic single-crystal diffracto- TiOz, MnO and total Fe as Fe,br; the penfield meter, with the results and estimated standard method for HuO*, and flame photometrv for deviations shown in Table 2. The elongation of NazO and KgO. Particular difficultie, w"r" the crystals is taken as the c. axis. "o- AGRELLITE, A NEW ROCK.FORMING MINERAL 123
TABTE2. CRYSTALLOGMPHYOFAGRELLITE TABLE3. '-RAY POI.IDERDATA FOR AGRELLITE
Pseudo-mnoclinic Pseudo-mnoclInic (hkl)o lrlcttntcrrue cetl tfue cel l sub-celI d(obs) .ro (ht:L)o d(ca]c)*" d(obs) r a'(calc) 40' 7.7i3(1)i a.,=[2011o=l3.B7lA a, = ha1 9.45 l.t 2.792 bo' 18.942{1) br.co=6.984 bz= bt 2.74 6.66 !{ 11 0 6.671 2.771 = = qr oo 6'984(1) cl bo'18.942 oz' "1 4,71 u 040 4.719 2,68 2,685 = oo' 90.148(5)" ol:ao:90.1480 "z "t 3.842 2,648 u I'r 2.65 I,J 8o - 116.84(1)" Bt = 94'lgs" 82=or fzrr 3.824 {i'^:2.645 2.610 = 94.145(7)' = 90'145' 3.73 211 3.725 Yo Yl 12= 11 ?.58 (;;: (200 3.456 Lattice P Lattice c Lattice t 3.44 5 3.435 2.562 = [iuo 2.560 /o=914.5(l)43 \.2uo v2 ,Uo 2.53 3.33 2zo 3.335 {iii 2.553 zo = 4 zt=a 22'? 3.204 * This unlt cell was chosenat the start of the lnvestlgatlon as 3.i9 v5 {rso (apparently) the reducedcell. After the paraneterswere reflned [o5r 3.I 73 It turned out not to be the reducedcell, but it was retained for t22O 3.162 2.43 l,{ convenlencenevertheless. Ihe reducedQell hasa = ll0ll" = 7.757, 2.36 VlJ b = [0I0]o = 8.942,a = [00]1"= 6.984[,a = 90.1480,B : ]16.61", 3.14 {83! 3:li3 2,31 S r.85.716. \ooz 3.il4 2.26 M parentheses devlation, ln tems Flgures in represent the standard 2.14 VH of least units cited to thei|lmdjate left, as given by the least- 3.05e 3.05 f_U squares refinsent. 2.l l l1 *z = nmber of unlts of tlacazsi4o]oFper cel l. \ r32 3.0s4 2.ee4 2.04 MS ?.99 [rr_, [022 2.e92 2.00 vl,l 2.e33 2.92 {ZZz An alternative double-volume unit cell can lo22 2.923 be chosen which has almost perfect monoclinic d-valuesin i. Photographicdata, 114.6m diareter Phillps. carera. Filtered Cu radiation. Manyrcre retlm!lons !r!n d geometry; dimensions are also given in Table 2. less than 2.04 rere observed. * = visually estimted intensities. vl'l = very weak,l'l weak' Oscillation photographs taken with co as rota' M = rediun. s = Strcnq, v = very strong. o*d- tion axis showed that L : even layer lines were values calculated fltm cell dimnslons in first colum of 2. mush stronger than the L : odd ones, and also Table that spots on the strong layer lines Out not those on the weak ones) appeared to be related by a mirror plane of symmetry perpendicular to co. of the reflections as seen on single-crystal pho- These features, strongly reminiscent of the situa- tographs. tion with wollastonite and pectolite crystals, were confirmed by Weissenbergand precessionphoto- graphs, and these also revealed that the a$ellite triclinic cell has not only pseudo-halvingof the INrnensp Spscrnur4 c.-axis, but also shows a pseudo-/ lattice type. The subcell which would result if only ths The infrared spectrum of agrellite is given in strongest reflections vrere considered is very Figure 1. nearly rnonoclinic in symmetry as well as in geo- metry; the parameters are included in Table 2.
Full intensity data have been collected and Pnvsrclr, AND OPTIcAL PRoPERTTES the crystal structure is under investigation by Bown & Gibbs. Agrellite forms crystals from a few mm up to 1@ mm in length. Color is white to greyish or greenish white; lustre pearly on cleavages. Cleavage {110} and {1T0} excellent, {010} Powder data poor. Hardness 5.5, specific gravity (meas- ured bv heaw liquid suspensionand subsequent of the liquid specific gravityl Interplanar spacings measrued from standard determination 2,902, calculated 2.887. powder photographs are given in Table 3, to- gether with visual estimates of line intensities. All measurements of optical properties were The photographs showed some preferred orien- made in sodium light. As with the single crystal tation, In assigning indice.s to some of these X-ray study the c-axis was chosen to coincide lines. account has been taken of the intensities with the elongation of the crystals. Properties 124 TIIB CANADIAN MINERALOGIST
FREQUENCY(CM-I) 1000 950 900 850 800
U o o.2 z. @ E
u' 04 @
o.5 3g\J Y 9E R3 3 oo 0.5 It2 WAVELENGTH(MICRONS)
U z
1600 r4oo ''?*roJ:i.' 600 5oo 4oo i:"r:T
Frc. 1. Infrared spectra of agrellite. (a) Schwarzkopf Microanalytical Laboratory, Woodside, N.y., U.S.A. (b) Depafiment of Mineralogy, University of Kiev, U.S.S.R. Absorption bands: vas- 1145, 1090, 1033, 1012,967,860; vs O-SiO-786; ys SiOSi- 698, 677,653, 619,. vs Si-O -538, 497, 485, 460, 436, 420 sh.
are: Ertinction anglesfor fragmentslying on na, L.567,nB 1..579,ny I.581, ny-na'colorless O.014, (010) ZYa negative cAzt 2 47", Oi\p*(010), in ([0) cAzt 0.5' thin section. (110) cAz' 5o Orientation of the principal vibration directions is shown in Figure-2 and is defined by the fol- lowing angles: Srestr,rry dp I (0I0) 0o 90o No systematic study of the stability has yet f G.tO) 66o m" been attempted. Attempts to synthesizeagrellite (if0) J. 106' 90o from oxide mixes have so far failed. pygliminsry x 2740 88 study of the system Na:O-CaO-SiOa-F suggests Y 1&[o 840 that agrellite has a primary phase volume adja- z 23" 60 cent to that of wollastonite and that its crvs- AGRELLITE. A NEW ROCK-FORMING MINERAL t25
rl
/ 1to
c ,6, 11o I .l 110 | i,"'
)
FIG. 2. The two most common habits of agrellite crystals: a) dominant form (010), and b) dominant form (110). The position of thte principal vibration directions X,Y,Z is shown in 2b.
tallization in preference to wollastonite is fav- Canada which are gratefully acknowledged.The oured by high au. chemical analytical work was done largely in the Department of Mineralogy and Petrology, University of Cambridge, while J. G. was on leave from the University of Toronto, and he DsnryertoN on rue Nens is indebted to Professor W. A. Deer and to The mineral is named after Dr. Stuart O. Mr. J. H. Scoon for the use of the Cambridge Agrell, Department of Mineralogy and Petro- rock-analysis laboratory. J. G. is furthel- in- logy, University of Cambridge, England, and debted to the Nuffield Foundation for a Fellow- was approved by the Commission on New Min- ship during this period. We are indebted to Mr' eral Names in June, 1973. Pronunciation is M. Haslop for the preparation of mineral con- and to Mr. K. Rickson for assistance a-grell'i?e. centrates in the X-ray laboratories. The University of Toronto electron microprobe is partly supported by National Research Council grants Pro- AcKNowLEDGMENTS .to, fessor J. C. Rucklidge to whom we are indebted This study has been financed by research for the supervision of the facility and for the grants from the National Research Council of data reduction programs employed in the 126 THE CANADIAN MINERALOGIST
and Crystal Chemistry of the Rare Elements for his cooperation and exchange of specimen material. Part of tht crystallographic work was done at Virginia Polytechnic Institute and State University, and M. G. B. is grateful to Professor G. V. Gibbs for his valuable advice and the use of his facilities.
RrrnnsNcEs
AeRorN, H. M. & GrrrrNs, I. (1974): Hiortdahlite from Kipawa River, Villedieu Township, Temis- caming Countyn Quebec, Canada. Can. Mineral. 12,241-247. Cunnre, K. L., Cunns, L. W. & GrrnNs, J. (1975): Petrology of the Red Wine Alkaline Complexes, Central Labrador and a comparison with the Ilimaussaq Complex, Southwest Greenland. Geol. Sarv. Can. Pap. 75-1, Pt. A, 271-280. Frc. 3. Stereographicprojection GITnNs, J., Gespannrrr, E. L, & Fr,esr, S. G. of optical and crys- (1973): The tallographicelements of agrellite. occurrence of vlasovite in Canada. Can. Mineral. 12, 2lt-214. & TurrLE, O. F. (1964): The system CaFr-Ca(OH)r-CaCOs. Amer. J. Sci. 262, 66-75. analytical procedures. It is a particular pleasure to record our gratitude to Dr. E f. Semenov of Manuscript received July 1975, emended October the Institute for the Mineralogy, Geochemistry 1975.