Canadian Mineralogist Vol. 15, pp. 108-112 (1977) SERENDIBITE FROM PENRHVN GROUP MARBLE, MELVILLE PENINSULA DISTRICT OF FRANKLIN IAN HUTCHEON AND AVRIL E. GUNTER Department of Geology, Carleton University, Ottawa, Ontario KIS 5B6 A. N. LECHEMINANT Geological Survey of Canada, 588 Booth Street, Ottawa, Ontario KIA OE4 ABSTRACT Serendibite occurs in skarn which formed be- t~een Aphebian Penrhyn Group marble and gra- mte on the Melville Peninsula, District of Fran- klin. The mineral is triclinic and the parameters of the reduced cell are a 9.513, b 10.001, c 8.622.A, a 95.85°, fJ 114.70°, 'Y 64.280, V=668.27.A3. Micro- probe analysis gave (wt. %) Si02 20.85, Alz03 40.20, FeO (total iron) 3.48, MgO 12.71, CaO 17.11 (B203 not determined). The optical proper- ties of the mineral for NaD are: 2Vy=81°, a 1.700 (pale blue-green), fJ 1.703 (pale yellow), 'Y 1.706 (moderate blue); axial r>v, inclined and horizon- tal dispersion. Serendibite is associated with fas- saite, uvite-rich tourmaline, clinozoisite, spinel, and calcite. Comparison with other occurrences suggests that the stability field of serendibite may be restricted to silica-undersaturated bulk compo- sitions. SOMMAIRE La serendibite se trouve dans Ie skarn qui s'est forme, entre Ie marbre du groupe Aphebian Pen- rhyn et Ie granite, sur la peninsule de Melville, dans Ie district de Franklin. Le mineral est tricli- nique, et les parametres de la maille reduite sont: a 9.513, b to.001, c 8.622.A, a 95.85°, fJ 114.70°, 'Y 64.28 0, V 668.27.A3. L'analyse It la microsonde donne en poids: Si02 20.85%, Al203 40.20%, FeO (fer total) 3.48%, MgO 12.71%, CaO 17.11% (B203 non determine). Les proprietes optiques de ce mineral pour NaD sont: 2Vy=81°, a 1.700 (bleu-vert pale), fJ 1.703 (jaune pale), "Y 1.706 (bleu moyen); dispersion des axes r>v; disper- sion horizon tale et inclinee. La serendibite est as- sociee It la fassaite, la tourmaline riche en uvite, Ja clinozoisite, Ie spinel Ie et la calcite. Par comparaison avec d'autres gites, on est amene It penser que Ie champ de stabilite de la serendibite peut etre li- mite aux compositions sous-saturees en silice. (Traduit par la Redaction) INTRODUCTION Serendibite was first described by Prior & Coomaraswamy (1903) from a contact zone between limestone and granulite near Kandy, Ceylon. Serendibite has subsequently been re- ported from remarkably similar occurrences near Johnsburg, New York (Larsen & Schaller 1932); Riverside, California (Richmond 1939); South Yakutia, Siberia (Shabynin & Pertsev 1956; Pert- sev & Nikitina 1959); and northeast Tanzania (Bowden et al. 1969). This paper describes the first Canadian occurrence of serendibite. OCCURRENCE A dark blue skarn mineral was identified as serendibite after the completion of a regional mapping project on the Melville Peninsula (Ree- sor et a1. 1975). Detailed mapping and sampling of the occurrence will not be practical until new programs are undertaken in the region. Serendibite was formed in a contact zone be- tween coarse-grained calcite marble of the Aphe- bian Penrhyn Group and intrusive pink leucocra- tic granite (NTS 46 K 14; UTM Zone 16, 568840, 7427420). The marble is part of a nar- row northeast-trending belt of Penrhyn Group metasediments infolded with granodiorite-gra- nite gneiss. Numerous small bodies of granite and pegmatite intrude both metasediments and gneisses. Pelitic and calcium silicate assemblages throughout the area indicate regional upper amphibolite facies metamorphism. Specimens containing serendibite are macro- scopically zoned. A narrow 2-4 cm band made up of dark blue serendibite and green diopside separates coarse-grained white diopside-calcite marble from a black tourmaline-rich band. Figure lA is a sketch of mineral zones dis- played in a thin section cut perpendicular to the zones. In the section, zone 1 is an equigranular mosaic of 2-5 mm pale blue-green tourmaline crystals with 5-10% interstitial colorless diop- side. Tourmaline grains adjacent to zone 2 or zone 3 are embayed and surrounded by color- less clinozoisite (Fig. 1B) or pleochroic blue serendibite (Fig. lC). Zone 2 is a discontinuous 3-6 mm wide clinozoisite-rich band. Clinozoisite grains poikiloblastically enclose tourmaline, se- 108
Transcript
Canadian MineralogistVol. 15, pp. 108-112 (1977)
SERENDIBITE FROM PENRHVN GROUP MARBLE, MELVILLE PENINSULADISTRICT OF FRANKLIN
IAN HUTCHEON AND AVRIL E. GUNTERDepartment of Geology, Carleton University, Ottawa, Ontario KIS 5B6
A. N. LECHEMINANTGeological Survey of Canada, 588 Booth Street, Ottawa, Ontario KIA OE4
ABSTRACT
Serendibite occurs in skarn which formed be-t~een Aphebian Penrhyn Group marble and gra-mte on the Melville Peninsula, District of Fran-klin. The mineral is triclinic and the parametersof the reduced cell are a 9.513, b 10.001, c 8.622.A,a 95.85°, fJ 114.70°, 'Y 64.280, V=668.27.A3. Micro-probe analysis gave (wt. %) Si02 20.85, Alz0340.20, FeO (total iron) 3.48, MgO 12.71, CaO17.11 (B203 not determined). The optical proper-ties of the mineral for NaD are: 2Vy=81°, a 1.700(pale blue-green), fJ 1.703 (pale yellow), 'Y 1.706(moderate blue); axial r>v, inclined and horizon-tal dispersion. Serendibite is associated with fas-saite, uvite-rich tourmaline, clinozoisite, spinel,and calcite. Comparison with other occurrencessuggests that the stability field of serendibite maybe restricted to silica-undersaturated bulk compo-sitions.
SOMMAIRE
La serendibite se trouve dans Ie skarn qui s'estforme, entre Ie marbre du groupe Aphebian Pen-rhyn et Ie granite, sur la peninsule de Melville,dans Ie district de Franklin. Le mineral est tricli-nique, et les parametres de la maille reduite sont:a 9.513, b to.001, c 8.622.A, a 95.85°, fJ 114.70°,
'Y 64.28 0, V 668.27.A3. L'analyse It la microsondedonne en poids: Si02 20.85%, Al203 40.20%, FeO(fer total) 3.48%, MgO 12.71%, CaO 17.11%(B203 non determine). Les proprietes optiques dece mineral pour NaD sont: 2Vy=81°, a 1.700(bleu-vert pale), fJ 1.703 (jaune pale), "Y 1.706(bleu moyen); dispersion des axes r>v; disper-sion horizon tale et inclinee. La serendibite est as-sociee It la fassaite, la tourmaline riche en uvite, Jaclinozoisite, Ie spinel Ie et la calcite. Par comparaisonavec d'autres gites, on est amene It penser que Iechamp de stabilite de la serendibite peut etre li-mite aux compositions sous-saturees en silice.
(Traduit par la Redaction)
INTRODUCTION
Serendibite was first described by Prior &Coomaraswamy (1903) from a contact zonebetween limestone and granulite near Kandy,
Ceylon. Serendibite has subsequently been re-ported from remarkably similar occurrences nearJohnsburg, New York (Larsen & Schaller 1932);Riverside, California (Richmond 1939); SouthYakutia, Siberia (Shabynin & Pertsev 1956; Pert-sev & Nikitina 1959); and northeast Tanzania(Bowden et al. 1969). This paper describes thefirst Canadian occurrence of serendibite.
OCCURRENCE
A dark blue skarn mineral was identified asserendibite after the completion of a regionalmapping project on the Melville Peninsula (Ree-sor et a1. 1975). Detailed mapping and samplingof the occurrence will not be practical until newprograms are undertaken in the region.
Serendibite was formed in a contact zone be-tween coarse-grained calcite marble of the Aphe-bian Penrhyn Group and intrusive pink leucocra-tic granite (NTS 46 K 14; UTM Zone 16,568840, 7427420). The marble is part of a nar-row northeast-trending belt of Penrhyn Groupmetasediments infolded with granodiorite-gra-nite gneiss. Numerous small bodies of graniteand pegmatite intrude both metasediments andgneisses. Pelitic and calcium silicate assemblagesthroughout the area indicate regional upperamphibolite facies metamorphism.
Specimens containing serendibite are macro-scopically zoned. A narrow 2-4 cm band madeup of dark blue serendibite and green diopsideseparates coarse-grained white diopside-calcitemarble from a black tourmaline-rich band.
Figure lA is a sketch of mineral zones dis-played in a thin section cut perpendicular to thezones. In the section, zone 1 is an equigranularmosaic of 2-5 mm pale blue-green tourmalinecrystals with 5-10% interstitial colorless diop-side. Tourmaline grains adjacent to zone 2 orzone 3 are embayed and surrounded by color-less clinozoisite (Fig. 1B) or pleochroic blueserendibite (Fig. lC). Zone 2 is a discontinuous3-6 mm wide clinozoisite-rich band. Clinozoisitegrains poikiloblastically enclose tourmaline, se-
108
rendibite, and diopside. Intricately zoned,twinned clinozoisite crystals display anomalousdeep blue to maroon interference colors and awide range of optical properties. Zone 3 is char-
SERENDIBITE 109
acterized by 0.5-10 mm serendibite grains whichpoikiloblastically enclose diopside (Fig. ID).Accessory minerals are colorless spinel and cal-cite. Diopside is concentrated along the boun-
FIG. 1. (A) Sketch of mineral zones (lantern slide J272-2 RA 74): (1) tourmaline+diopside; (2) clino-zoisite; (3) serendibite+diopside; (4) diopside+caIcite. (B) Zones 1 and 2, crossed nicols: tourmaline(To) embayed and surrounded by zoned, twinned clinozoisite (Cz). (C) Zones 1, 2, and 3: serendibite(Se) enclosing tourmaline. (D) Zone 3, crossed nicols: polysynthetically twinned serendibite enclosingdiopside (Di). (E) Boundary between zone 3 and 4: serendibite, diopside, calcite (Cc)...
1 1 0 TTIE CANADIAN MINERALOGIST
TASLE T. X-RAY MIOER DIFFMCTION PATIIRN OF SEREI{DIBITE FROiI
The ce]l of Buerger & venkatakrlshnan (1974) 8nd susse (1968) are
related to the cell adopted ln ihls study by the transfomtlon
mtr ' lces 001/ lOO/010 and 001/ l0l / lT0 respect ivelv. The relat lonshlp
bet lreen the present cel l and the cel l of Pertsev & Nlkl t lna (1959)
is m@rtaln.
(pale blue-green), B 1.703 (pale yellow), y 1.706(moderate to bright blue).
2V was determined on the universal stageusing a Leitz highpower monochromator to settr. For )t of 46O 546, and 66O nm, 2V, is 78.5,80, and 82o, respectively.
Serendibite has axial dispersion r>v, super-imposed on a very strong inclined dispersion andweaker,horizontal dispersion.
X-Rev Cnvsrer,r,ocneprrv
Prior & Coomaraswamv (1903) and Larsen &Schaller (1932) suggested that serendibite wastrislinic on the basis of its optical properties.Susse (1968) confirmed the triclinic symmetryand determined parameters of a non-reduced cell(Iable 2). Machin & Susse (1974) assigned se-rendibite to the aenigmatite group. Buerger &Venkatakrishnan (1974) established the spacegroup as Pl, described the structure as similar tothat of sapphirine-lTc and aenismatite, and re-ported parameters of a tri-acute reduced cellClable 2) calculated from the cell reported bySusse (1968).
Precession photographs of serendibite fromMelville Peninsula were prepared from twotwinned crystals pging MoKa radiation. Thepowder diffraclion pattern given in Table 1 wasindexed by comparison of observed and calcu-lated d-values using the single"crystal photo-graphs as a guide. The parameters o-f the reducedtricliuic cell were obtained'from the precessionphotographs and refined by a least-squaresmethod using the powder diffraction data (Ia-ble 1). Cell parameters ate compared in Table2 with those given for serendibite from otherlocalities.
The serendibite twin plane (101) is a pseudomirror plane. The l-axis precession photographsshow that reflections from individual II of thetwin coincide with those of individual I when
DirectCel 1
023 2,3I.951tzT 2.34891 z'54t
"427 ?.3/F.7'340 2,24461z4l z.zmsl z' '4r ru247 2.24X'3'UI 2.16r'r I42T 2.16081 2.15202! 2.1594,133 2 .1174)104 2 . lo92 l 2 .10840r 2 .1073)22T 2.0342 2.03BJ Z t a . u s a t l , ^ a 1442 2.O31tt341 2.0202 2.0t8]x3 1 .9785 1 .978
r 2l addlt lonal l lnes wlthCobs less than 1.978
'15
tn
70
705U'I
,bm c@ra,lntensltles.
dary separating zone 3 from zone 4 (Fig. 1E).Zone 4 is a coarse-grained diopside-calcite mar-ble. Thin veinlets of clinozoisite, scapolite, calciteand rare prehnite cut all zones.
Two other specimens which do not containserendibite are available from the skarn. A black,oxide-encrusted specimen is composed of. I-2mm diopide crystals set in a very fine-grainedintergrowth of preh:rite and white mica. Severalradiating or sheaf-1ike aggregates of prehnite upto l mm across are associated with zoned clino-zoisite crystals. Dark red-brown sphene is a com-rnoo accessory mineral. Pyrite and hematiteoccur in veins. The second specimen is a coarse-grained light grey scapolite-rich rock. The rockis made up of.8A7o scapolite, 15% diopside andaccessory sphene, calcite, quartzo white mica,trernolite, and clinozoisite. X-ray measurementof. 20nu-2,0:;.2 (CuKrr)=3.68o indicates that thescapolite is a calcium-rich mizzonite containingapproximately TOVo meionite @urley et al.7961).
Pnvsrcer- eNp Oprrcer. PRoPERTIES'Serendibite occurs as irregular dark-blue
grains up to 10 mm in lqrgth with no crystaltenninations and an imperfect cleavage or frac-ture. On a mierosoopic scale, polysynthetic twin-ning is prominent with lamellae ranging in widthfrom O.OO3 mm to 0.5 mm ,(Fig. 1D). The opticalorientation. of individual twins is sy'mmetricqbout the,composition plane. The indices of re-fraction (Na lieht) and pleochroism are: c.1.700
SERENI}IBITE
T A B L E 3 . P A R T I A L M I C R O P R O B E A N A L Y S E S O F s E R E N D I B I T E , T O U R M A L I N E , C L I N O Z O I S I T E , A N D P Y R O X E N E F R O MT H E I { E L V I L L E P E N I I { 5 U L A . D A T A O F O T H E R A U T H O R S I N C L U D E D F O R C O M P A R I S O N
M e l v l l l e P e n l n s u l a ( J 2 7 2 R A - Z 7 4 )2 . T i l l e y ( 1 9 3 8 ) : f a s s a l t e , A d h e k a n r r e l a , C e y l o n ( f a s s a i t e - s p i n e . l r o c k )3 . I l l l e y ( 1 9 3 8 ) : f a s s a i t e , M o n z o n i , T l r o l ( f a s s a , l t e - s p i n e i r o c k )4 . T i 1 1 e y ( 1 9 5 1 ) : g r e e n c l i n o p y r o x e n e , K l l b r i d e , S c o t l a n d ( z o n e d s k a r n )5 . P r l o r & C o o m a r a s e l a m y ( 1 9 0 3 ) : s e r e n d i b l t e , 6 a n g a p l t l y a , C e y l o n ( r * N a 2 0 + r , t 2 O = 0 . S 1 ; K 2 O = O . Z Z )5 . L a r s e n & S c h a l l e r ( 1 9 3 2 ) : s e r e n d i b l t e , l . l a r r e n C o u n t y , N . y . ( a v . o f 2 a n a l . )7 . P e r t s e v & N l k l t l n s ( 1 9 5 9 ) : s e r e n d l b i t e , T a e z h n y d e p o s l t , s o u t h y a k u t l a ( 3 4 7 4 )8 . P e r t s e v & N i k i t i n a ( 1 9 5 9 ) : s e r e n d i b i t e , T a e z h n y d e p o s l t , s o u t h Y a k u t l a ( 5 4 0 6 - a v . o f ? a n a l . )
k=Zn and reflections from individual II fall half-way between those from individual I along thea* direction when k=2n+1. Thus twinning hasthe effect of doubling the a axis.
Mrcnopnons ANer,ysns AND PARAGENEsIS
Tourrnaline, clinozoisite, diopside, and seren-dibite from specimen 1272 RA-z 74 were anal-yzed on the Cambridge Instruments Microscan5 at Carleton University (accelerating voltage 15kV, sample current 40 nanoamps). Standardswere as close in composition to the analyzedminerals as possible. Standards fs1 l6urmaliris,clinozoisite, and serendibite analyses were gar-net (Si,Al), biotite (Fe, Ti, Na), and pyroxene(Ca, Mg). For the diopside analysis, standardswere pyroxene (Ca, Mg, Si) and biotite (Fe, Al,Ti and Na). Corrections for absorption and fluo-rescence effects were computed using a revisedversion of EMPADR VII (Rucklidge & Gaspar-dni 1969). Li and B analyses of individual rnin-erals by wet-chemical methods were precludedby sample limitations. Analyses are comparedto published serendibite and diopside analysesin Table 3.
1{umin6gs diopside ,(fassaite, 8.t97o NaOs)coexists with alumina-rich serendibite @A.2oy'o
Al,O,) in the Melville assemblage. The fassaiteis similar in composition to skarn pyroxenesfrom spinel-clinopyroxene associations (fable3). No published analyses of clinopyroxenesfrom other serendibite occurrences are avail-able, but the absence of quartz and the com-mon'association with spinel suggests that theseclinopyroxenes are also fassaitic.
The high CaO content (4.58Vo) in the Mel-ville tourmaline is typical of uvite-rich tourma-lines from dolomite and limestone skarns (Sha-bynin 1974). Association of tourmaline withspinel-clinopyt'oxene rocks is ,uncommon ex-cept in rare parageneses which also coutainserendibite. Textural evidence shows serendibitereplaced tourmaline in the South Yakutia occur-rence (Shabynin & Pertsev 1956) and in theMelville assemblage (Frg. 1C). The absence ofquartz from all reported serendibite associa.tions suggests that the stability field of seren-dibite may bo restricted to sifica-undersatur-ated bulk compositions.
AcKNowLEDGMENTS
The unusual skarn association was recog-nized and sanpled in the field by J. R. Hen-derson. R. I( Herd tentativelv identified seren
112 THE CANADIAN MINERALOGIST
dibite in hand specimen, contributed numeroushelpful suggestions, and reviewed the manu-script. G. Y. Chao made available the single-crystal apparatus in his laboratory, gave guid-ance and instruction during the single-crystalwork, contributed FORTRAN IV programs forthe refinement of cell parameters, and providedhelpful suggestions with the manuscript.
This study was partly supported by NRCgrants A-1135 (Chao) and A-7874 (Watkinson).
REFERENCES
BOWDEN, P., VaN KNORRING, O. & BARTHOLEMEW,R. W. (1969): Sinhalite and serendibite fromTanzania. Mineral. Mag. 37, 145-146.
BUERGER, M. J. & VENKATAKRISHNAN,V. (1974):Serendibite, a complicated, new, inorganic crys-tal structure. Proc. Nat. Acad. Sci. USA 71,4348-4351.
BURLEY, B. J., FREEMAN, E. B. & SHAW, D. M.(1961): Studies on scapolite. Can. Mineral. 6,670-679.
LARSEN, E. S. & SCHALLER, W. T. (1932): Seren-dibite from Warren County, New York, and itsparagenesis. ArneI'. Mineral. 17, 457-465.
MACHIN, M. P. & SUSSE, P. (1974): Serendibite:a new member of the aenigmatite structuregroup. Neues Jahrb. Mineral. Monatsh., 435-441.
PERTSEV, N. N. & NIKITINA, I. B. (1959): Newdata on serendibite. Proc. All-Soviet Mineral.Soc. 88, 169-172 (in Russ.).
PRIOR, G. T. & COOMARASWAMY,A. K. (1903):Serendibite, a new borosilicate from Ceylon.Mineral. Mag. 13, 224-227.
REESOR,J. E., LECHEMINANT,A. N. & HENDERSON,J. R. (1975): Geology of the Penrhyn Groupmetamorphic complex, Melville Peninsula, Dis-trict of Franklin. Geol. Surv. Can. Pap. 75-1A,349-351.
RICHMOND,G. M. (1939): Serendibite and asso-ciated minerals from the new city quarry, River-side, California. Amer. Mineral. 24, 725-726.
RUCKLIDGE,1. C. & GASPARRINI,E. L. (1969):Electron microprobe analytical data reduction(EMPADR VII). Dep. Geol. Univ. Toronto.
SHABYNIN,L. I. (1974): On some distinctive fea-tures of chemical composition, optical proper-ties, and parageneses of the tourmalines in mag-nesium-skarn ore deposits. Soviet Geol. Geo-phys. 15, 28-36.
& PERTSEV,N. N. (1956): Warwickiteand serendibite from magnesium skarns 'ofsouthern Yakutia. Proc. All-Soviet Mineral. Soc.85, 515-528 (in Russ.).
SUSSE, P. (1968): Serendibite, space group andcell dimensions. Naturwiss. 55, 176.
TILLEY, C. E. (1938): Aluminous pyroxenes inmetamorphosed limestones. Geol. Mag. 75, 81-86.
(1951): The zoned contact-skarns of theBroadford area, Skye: a study of boron-fluo-rine metasomatism in dolomites. Mineral. Mag.29, 621-666.
Manuscript received April 1976, emended Novem-ber 1976.
