971
The Canndian Mfurcralo gist Vol. 36, pp.971-980 (1998)
A NEWTYPE OF SCANDIUMMINERALIZATION IN PHOSCORITES AND CARBONATITESOF THE KOVDORMASSIF, RUSSIA
RUSLAN P. LIFEROVICHI.VIKTOR V. SUBBOTIN,YAKOV A. PAKHOMOVSKY eIlo MARGARITA F. LYALINA
Geological Instirute, KoLa Science Centre, Russian Aca.demy of Sciences, 14 Fersman Street, Apatity, Murmansk region 184200, Rwsia
AssrRAcr
Scandium mineralization of a new genetic type has been discovered in the Kovdor alkaline-ultrabasic massrf, Kola Peninsula Russia.Itis representedby a new mineral, juonniite, simplified formutaCaMgsc(PO+)z(OII)'4HzO, occuning in low- temperature hydrothermal assemblages in the phoscorite - carbonatite complex of the Kovdor massif. The mineral forms spherulites up to 0.8 mm in dirmeter and is associated with late carbonates and hydrous phosphates. Juonniite occlxrences are confined to a linear reactivated fault, which intersects phoscorites and carbonatites. Metasomatism of phoscorites caused almost a two-fold enrichment in Sc in clinohumite-bearing units. Late hydrothermal solutions a.ffected cataclastic clinohumite-bearing phoscorites along the fault zone; the subsequent dissolution of sulfides ald Sc-bearing minerals (e.9., forsterite, baddeleyite, pyrochlore-group minerals, etc.) was accompanied by mobilization of traces of Sc, most likely in the form of carbonate and iulfate. Fluorapatite-bearing carbonatites with abundant cavities provided the necessary conditions for the precipitation of scan- dium in the form of a hydrous phosphate,juonniite.
Keryord.s: sandium, carbonatites, phoscorites, clinohumite, cataclasis, mineralization, juonniite, hydrothermal alteration, Kovdor massif, Kola Peninsul4 Russia.
Somaamn
Nous documentonsun nouveau genre de min6ralisation en scandium, d6couvert .lans le msssif alcalin et ultrabasique de Kovdor, dans In pf,ninsule de Kol4 en Russie. Cet enrichissement se manifeste par la prdsence de la nouvelle espbcejuonniite, dont la formule simplifi6e serait CaMgSc@O+)z(OlI).4HzO, dans des assemblages hydrothermaux de faible tempdrature des phoscorites et carbonatites du msssif de Kovdor. k min6ral se pr6sente en spherules atteignant 0.8 mm de diambtre; il montre une association avec les carbonates et les phosphates hydratEs tardifs. Les incidences dejuonniite se limitent d une faille lin6aire r6asttv&,1son intersection avec les phoscorites et carbonatites. Une m6tasomatose des phoscorites a men6 d un d6doublement de la teneur en Sc des unitEs contenant la clinohumite. Des solutions hydrothermales tardiyes ont affect6 les zones broy6es d slinshrmite dans les phoscorites le long de la faille. La dissolution de su11|n"ss1 cle mindraux porteun de scaldium (e.9., forst6rite, baddeleyite, min6raux du groupe du plnochlore) a caus6 une mobilisation de traces de Sc, probablement sous forme de carbonate et de sulfate. t.es cavitps abondantes des carbonatites d fluorapatite ont fourni les conditions n6cessaires pour la pr6cipitation du scandium sous forme de juonniite, p66sphate hydrat6. (Traduit par la R6daction)
Mots-cl6s: scandium, carbonatites, phoscorites, clinohumite, cataclase, min6ralisation, juonniite, alt6ration hydrothermale, mas- sif de Kovdor, pdninsule de Kola, Russie.
hnnooucrroN ixiolite. In carbonatitesassociated with alkaline- ultrabasicrocks, scandium mineralization is known only The only occurrenceof a scandit'- mineralfrom the in dolomitic carbonatitesof FenoNorway, where Kola region was describedftom a granitic pegmatite thorweitite occursas inclusions3-5 pm acrossin asso- located in the central part of the Kola Peninsula ciation with Sc-bearingcolumbite and ilnenorutile (Voloshinef aL 1991);there, thortveitite was found as a (lr;o\ 1977). single inclusion -30 pm acrossin garnet- ilmenite A low-temperatureSc-rich association of an essen- a9gregate.The gamet is associa$edwith ilmenorutile, tially new genetic type has been discoveredin the which also containsfine inclusionsof Sc-bearins Kovdor phoscorite- carbonatitecomplex. Late
I E-mail address: [email protected]
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dolomitic carbonatiteswith abundantcavities were gies in the stockwork.All the rocks conraingreen phlo- foundto ssatainjusnniite, a new hydrousphosphate of gopite and early light-colore.dbaddeleyite (baddeleyite CA Mg and Sc of the overite group (Liferovich et aI. I), ttre averageabundance of which is about0.1 - 1997).The environments ofjuonniite mineralization, to O.2wt.Vo. be describedhere, provide new insight into the In the centerof the southernpart of the phoscorite geochemistryand metallogeny of scandium. stock,there are bodies ofclinohumite-bearing phosco- rite (Fig. 3) that are consideredto have resultedfrom Bnmr DpscnnnoN oF Trfi Kovoon Massm metasomatismof apatite- forsterite - magnetite- calcite phoscorites.Metasomatism is manifestedby Discoveredn 1932,the Kovdor massifand its iron intensivereplacement of forsteriteby clinohumite,crys- ore and phlogopite depositshave beeninvestigated in tallization of late calcite and red tetra-ferriphlogopite, detail (Kukharenkoet al. 1965,Ternovoi 1977,Kogarko which forms a pseudomorphby replacementafter early et al. 1995).This massifis the largestof the Caledonian green phlogopite,the formation of late generationsof alkaline-ultrabasiccomplexes of the Fennoscandian accessoryminerals of Zr and Nb (dark secondary Shield. It is locatedin a zone of Paleozoictectonic baddeleyitetr, uratroanpyrochloreo zirconolite), sulfide activity, in which most murssifsof this kind areconcen- enrichmentofrocks, andthe appearanceofamphibole trated. and ch-lorite.The metasomatismalso resultedin the The Kovdormassif, emplaced in thegneisses of the increaseof the naturalradioactivity of the rocks. Late ArcheanWhite SeaGroup, is surroundedby a rim In thesame part ofthe phoscoritestock, carbonatites of fenite up to 500 m in width. The subverticalcontacts form a network of subverticalveins intersectingthe ofthe intrusion,according to geophysicaldata, continue glinohrmite-learingphoscorites. The carbonatitesare down to a depthof morethan 15 km. The intrusionis massive,light-colored rocks of variablecomposition, concentricallyzoned (Fig. l). The main phasesare includingcalcitic and dolomitic varieties. The location olivinite - pyroxenite in the central part and ijolite - ofdolomitic carbonatitesand zones ofbrecciation and melteigitein the marginalzone. Nepheline pyroxenites, cataclasisin thephoscorites is controlledby a long-lived turjaites,melilite- andmonticellite-rich rocks androcks NE- andN-trending faults (Fig. 2). The carbonatiteveins of the phoscorite- carbonatitecomplex also are abun- and the phoscoritesaffected by cataclasisand hydro- dant. Coarse-grainedand pegmatite-likerocks with thennal alterationin the fault zones(particularly in the phlogopite,diopside and olivine are exploited in a centraland easternparts of the phoscorite- carbonatite phlogopitedeposit in the northernpart of massif,and its complex:Fig. 2) containnumerous cracks and cm-size crust of weatheringis a vermiculite deposit. cavities.The cavities in somecases account for lVl1%o Phoscorites(baddeleyite - apatite- magnetiteores) of a rock's volume. They contain late hydrothermal and calcitic and dolomitic carbonatiteshave a variable mins14ls,among which arerare hydrous phosphates of compositionand occur in the southwesternsegment of Mg, Fe2*,Ca, Sr, Bq Al,Zr andSc:juonniile, goyazite, the massif as a stock intrudedbetween pyroxenite and gorceixite, collinsite, bobierrite, baribite, vivianite, ijolite units (Fig. 2).The srock is borderedby fine- kovdorskite, rimkorolgite, strontiowhitlockite, hydro- gfained apatite- phlogopite - forsterite rocks, which xylapatite, catapleiiteand hydrous mineralsof 7t and areconsidered to be silicalerocks metasomatized bv the Nb, Juonniileoccurs just within the zoneswith cavern- fluid phaseof the phoscorite- carbonatiteintrusion ousdolomitic veins,which arespatially associated with (Temovoi1977). The position of thephoscorires is con- the fault zone and cross-cutthe stock-likebodies of trolled by thejunction of at leasttwo major linear faults, slinofurrmite-lsaringphoscorites @9. 2). complicatedby a seriesof ring-type, conical and radial fauls @unaev 1982).The stock, extendingin rhe N-S ANaryrrcar Merlops direction for 1500 m, is asynunetricallyzoned with a multiple-phase,telescoped core of phoscorite.The width All rock types of the Kovdor massif and the ofthe stockin outcropranges from 150to 800m, reacn- phoscorite- carbonatitecomplex, as well asmain rock- ing its maximum in an areaof intersectionof the ore- forrningand someaccessory mins14l5, were analyzed sen6slling faults. The stockhas been traced by drilling for Sc. Scandi'm contentsbelow 100ppm weredeter- down to a depthof 2 km. At depth,the orebodynarrows minsdfy a quantitativespectral analysis. Duplicates of and dips steeplyto the south.The Kovdor phoscoriles rocksand minerals, analogous to the analyzedsamples experiencedvarious posfuagmatic processes,such as in eachset, were usedas standards.The Sc contentsin metasomaticalteration, cataclasis,and weatherins. these analytical standardswere determinedby instru- Theserocks are characterizedby significant variatiois mentalneutron-activation analysis (INAA) in two inde- in the ratio of constituentminerals: fonterite, magnet- pendentlaboratories: the GEOCHI,Moscow, and the ite, apatite,calcite, dolomite and phlogopite.Apatite - University of Massachusettsat Lowell. An analytical forsterite - magnetiteand forsterite - magnetiterocks accuracyof scandiummeasurements in the rangeof and their calcite-bearinganalogues are predomin411. &-l2%orelatle wasattained. Figure 2 illustratesthe distribution of the major litholo-
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LLL l.{- A lJ rv I la LILL nt':' \ ,t ;'e , :.1 \L.LLt i ^... :^ \G--rl :^ l.r' 3l {T}-. t -+- X ::^ I I|^i rt- tU i + { -t& t .Y lvllAl : --l- + / A, v- tt L i + fx 01 ^i,. -F >'1 t't;,$ )j .1._ | + ,'t' >^'a. - x .{- i".. phoscorite-carbonatite E6q] x rnelilfteand WlilHn[?ffir** E monflcelltterod< @lilRnn"=v"nr," E turJaib F-I"-l erbonatite:aeglrlne-catcite (a); Moxenlte and LiJ-gl apattecldte (b); E nephellnepyroxenlte micaceous f| E ollvinite fTTl phtogopitediopside-olivine l-H-l pgrnatoid Ef fenite pilogoptte-dloNdeotivlne gneissand granitegnelss @ E of Upper AR Itw|lte Sea Group lv .. v I ooarBe{rainediplfte and gmlogical boundary(a), outmrd $bordlnate rnelteigite ffi boundaryof lenitisatbn aureole(b) Flc. 1. Geological map ofthe Kovdor massif, after Ternovoi (1977), with some additions. The square area shows the outlie of Figure 2.
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Juonnllte brderite-nEgneffie and apaute-for6tefile- Pyroxenfiea]d EtroccwgncE W rnaglFtb phoscorlte n€phellnepyroxenlte sari6of dolomfteca6o- EI natfis velno:ordlnary (a), fln€ gralned aFtte-brgorte calcffe-"teffinlphb-, cavenpusmh€ralH(bl. goplte'{remome E (not ln saale) ffi ahd brsterlte rod( E rod( dFohumlb'beafuq reilpho€codb trI f€nlte TI oltuhlte calcfte apffie- ffi carbomtlle ET -'fiarrcollte' rock a tedorilolhult apatte Hc. 2. Geological skerch-map of the Kovdor phoscorite - carbonatite (ore) complex, after Temovoi (1977), with some additions. Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 SCANDITJM MINERALEATION. KOVDOR MASSIF. RUSSTA 97s ffiFffi**@ffis[) ffirffi$ffiil@Iffi"T,{ffi ffi 6od|'rerc66of core, I rlr, I vtlggV (FE)mIle gfrorfispftffludffe,kov- l3J oarbomfre tudrffe lfil serpertrrffion fiso.ne l+:-:l andchloritizatbn Flc. 3. A sketch-map of one of the localities ofjuonniite mineralization. A plan of the surface bench (mine horizon: 35 m, eastem part of the Kovdor iron-deposit). Theminerals containing more than 100 ppm Sc were phoscorites(especially clinohumite-bearing varieties) analyzedwith a CamecaMS-46 electronmicroprobe at andin mineralizedvuggy dolomitic veins.In othertypes an acceleratingvoltage of 20 kV (30 kV for Sr) and a of silicaterocks and carbonatites,only low concenfra- samplecurrent of 15-30 nA. Apatite (for Ca and P), tions of Sc arerevealed. It shouldbe notedthat the com- forsterite (Mg), thofieitite (Sc), lorenzenite(Ti), syn- mon dolomitic carbonatitesthat are not affectedby thetic MnCO3(Mn), hematite(Fe), metallic niobium hydrothermalalteration are the poorestrocks in terms (Nb), baddeleyite(7r), celestine(Sr) and barite @a) of Sc (Table1). were usedas standards. Diopside,containing about 130 ppm Sc, is thedomi- Concentratesof baddeleyite,the main Sc-bearing nanthost of Sc in pegmatite-likepblogopite - diopside mine1zl,from varioustypes of phoscoritesalso were - forsterite rocks. The main rock-forming minerals of analyzedfor Sc, using the X-ray fluorescencespec- phoscoritesand carbonatites, pblogopite, apatite, calcite hometerVRA-20. anddolomite, contain less than 10 ppm Sc.Magnetite, forsteriteand clinohumitecontain up to 110 ppm Sc. ScaNorurunr RrcKs eNp Mnvmers Accessoriesof 7r andNb in theserocks are more sig- on rlre KovDon Massrr nificantly enrichedin Sc. The dominanthost of Sc in tle commonphoscorites is baddeleyiteI (Table 2), The geochemicalcharacteristics of the Kovdor which containson average0.06 wtVo Sc2O3according massif conform with the generallyrecognized features to 50 electron-microprobeanalyses (including the data of alkaline-ultrabasiccarbonatite-bearing massifs of Polyakov & Polezhaeva1991). According to the (Kukharenkoet al. 1965,l97l,Eby 1973).The Sc resultsof X-ray-fluorescenceanalysis, this value lieS contentsin the main typesof rocksand some minslalg within therange 0.10-0.18 wt.Vo SczOt Clable 3). are given in Tables 1-4. Scandiumis stronglyenriched The late baddeleyite(If) from clinohumite-bearing in pegmatitic phlogopite- and diopside-rich rocks, phoscoritescontains on average0.26 wt.Vo Sc2O3 Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 976 THE CANADIAN MINERALOGIST TABLE I. SCAI{DIIJM CONTENTOF ROKS OF TIIEKO\IDORMASSIF, TABLB 3. CONCBhITRATIONOF Sa AND sPr EglrD EI.EMENTS IN AS DETRMINE) BY QUANTITATTVESPECTROGRAPHIC AI.IALY$S THE BADDELEYITEFRACIION OF VARIOUS RO(I TABLB 2- CSE\{ICAL COMPO$ION OF S&BEARING ACGSSORY MINERALS blage of the vuggy mineralized rocks has not been OF PHOSCORITBS OF TIIB KOVIER MAStr, detected. tn late calcite, dolomite, hydroxylapatite and AS DRTRMINED BYBLECTRON.MIAOPROBEANALYSB other hydrothermal phosphates, Sc does not exceed Pb{)qib Cliehuiteb@iryph@it€ 10 ppm. [n secondary Fe- and Mg-bearing silicates n"aad.Vi*r g"dda.yit*n zir-*tit" *H"hl"* Xm (amphibole, chlorite, serpentine),the abundanceof Sc NsrO 0.98 0.n t.t5 5.t0 is 2.5-3 times less than in primary forsterite and rrco 0.62 0.80 CsO - 0.03 l2B ll.?0 234 z.er n.n clinohlmite. MnO 05 O27 0.t7 The accessoryphases baddeleyite (both generations), Feo 0.o7 0.15 1.54 7.A Lr7 1.94 0.76 sro 2.t3 054 0.37 zirconolite and uranoan pyrochlore were corrodedo dis- BaO 6.78 0.u Pbo 0.75 0.69 2.54 solved or transformed to other minerals sFreciesin zones Scp, 0.03 0.14 0.07 0.55 0.08 0.12 0.07 0.05 035 of hydrothermal alteration. An example of Ia,ol o23 0.29 intense Cqq 125 1.86 0.n baddeleyite corrosion is shown in Figure 5. Thereafter, Nd,q 0.n r.3l 023 fiq 0.08 0.2r 18.26 18.40 5.92 1029 1.@ Zr precipitated" probably in the form of zircon. A late hot 98.14 C1.64 95.31 9520 3139 29.83 2 4.t4 l.6l IIJ(}, 221 2.r7 2.08 l.&r 0.38 0.40 generation of zircon relative to baddeleyite and Thob 2SA 2.54 l.0l Ln t31 zirconolite is identified in the clinohumite-bearing uor 1823 15.42 1926 NUO: 1.65 1.43 20.03 1939 35J9 13.7t 35.00 phoscoritesfrom the exocontactof the wggy dolomitic TaOs - 029 1.06 123 n.n2 759 t4.76 Tobl [email protected] 90.98 99l, 9.69 Et.79 96JI 91.65. 92.44.. .63 veins. At some st4ge of the hydrothermal process, the newly crystallized zircon also became unstable, and was VshE@ quotedinwr%. * Itrshds 2.5t% Siq. r. Irclllds l.otrlo K2O. replaced by catapleiite. The latter is common in cavities Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 SCANDIUM MINERALZATION. KOVDOR MASSIF, RUSSIA 977 Hc. 4. Spheruliteofjuonniite on crystalsof kovdorskite.Scan- Frc. 5. Conoded crystal of baddeleyite within aggregates of ning electronmicrograph. Width of field of view: 40Opm. late calcite from clinohumite-bearing phoscorites. Scan- ning elecfton micrograph. Width of field of view: 95 pm. with juonniils and other minerals of the hydrothermal hydrothermalalteration of phoscoritesand dolomite assemblage.Under hydrothermal conditions, uranoan carbonatites,there is only one M-bearing mineral, pyrochlore was replaced by common Ca-Na-pyrochlore which is closeto ternovite(Subbotin et al. 1997)in and, later, by Ba-bearing pyrochlore. In zones ofintense composition.Except for zircon,which in somecases containsnoticeable Sc (Iable 4), thelevel ofSc in these TADLE 4. CIIEMICAL COMPO$IION OF I.ATE FYDROTHERMAL lateminerals is below the limit of detection. MINERAIS OFA AND Nb FROMALTERED DOI'MITIC CARBONATITESAND PHOSCORITESOF TIIEKOVDORMASSIF, AIt DETERMINEDBYELECTRON.MIROPROEIEANALYSN Drscusstott Zim Pymhlm Ba-bsrirg T@vitelike Sc mineralizationin the pyrcblore pbam The main factor leading to phoscoritesand carbonatiteswas postcarbon- Nazo 894 2.54 Kovdor KP 0.t5 atite tectonicactivity followed by hydrothermalaltsra- Mgo t2.t3 l2.ll 4.61 Cro 10.33 1224 13.55 0.13 tion of the rocks.These processes were most intense in N{uO 2.54 0.47 0.12 tectonic zonesalong NE- and N-trending faults, which Fd) 2.ll 0.,t0 - 0.96 0.09 sIo 1.33 0.54 Lt4 2.59 affectedthe dolomitic carbonatiteveins andintersected BeO 1.54 3.53 -t Pbo 0.15 1" the host phoscorites,mostly the clinohumite-bearing Sc!O! 11.85 14.11 0.05 varieties.The zone ofjuonniite occutences is tracedfor l.ror 0.35 o.n cer& :: 0.99 0.42 at leasttens of metersvertically and a few hundredsof Nd& o.20 0.20 shown that the zone is sioz ,i.ot meterslaterally. Sampling has nq Lq 2.44 0.07 lens-shapedor discontinuous,controlled by the struc- za 6625 0.t5 Hq :": 1.05 :" tural featuresof postcarbonatitetectonics. The abun- Uq o.t, danseofjgsnniite decreasesrapidly with distancefrom PrQ 16.73 36.17 0.18 Nb,o' 6825 62.91 59.28 the fauls in the centraland easternparts of the phosco- TeO: 1.76 3.90 0.17 rite - carbonatitecomplex. Totel 79.31 99.83. r* ol n.95 93.15 u.35 The probablesources of Sc were baddeleyite, ValE m quoledla rrtyo.' rtrt\.ta?fr/ofuOt dcmined by tho Ped€ld Erflo4 zirconoliteand uranoan pyrochlore, Destabilization and Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 978 TABLE 5. GENETIC TYPES OFDEPOSITSAND OCCTjRRENCFJOF SCANDIUMMINEMLS Genetiotype Assooiaedninerals Occurrenrces Importa"ce Slficde nfuerah Thorh/eitite ffiicpegnatits Gamet,ilm€oo'rutilg monazite IveJand,Norway Smalld€'po{i* b€ryl ;rcoq sc-b€a;ng HoElo Bghnmq lvladagolcd Kreli4 KolaPeninsla Scis'triffcider€st mly B8Ej'tE Metasomaicrcc,ks Biotb, aSito,U-b€odng mi@als, Kunh, Ahai Mddle-sizecoqlc reJ8td to toumalino, fluorqftomls So-REE-Udsposit quertzporphyries of the rareortl elermems Carboufit€s ofan Semdim columb,itelniobian rutile FerqNorway A poosbleeowco of rlkalinerUltabqric dolmite aokerite,cHodte scodiurn msif quartr, qd'ts Voils ingranitesd QraE, nicrocline chlorite Tsvsto, Swibedmq Of sciemificiterest only pcpadt€s h€rndit6,cslcite Ke@ fazkhstm Anazonitic pegmaoit€s Beryl, quartz,albite Telemark,Nolwuy Of scieffic iniumt only Jervisits Cavhienin Quartz,orthocltse, altits Bavao, Italy Of scisifno ideftst only .-.crnditg slpinogrmilos Phorylzmntuioals Pr€tulit€ Alpinevoim @te, eotdathte, xenotine-(Y) Styri4 Auffiia Of scierilificineret only tlorcrctb Kolhckite Voirb inW--Sn-bsing eoyAte,Sd@Mt4@ Tigrinoo,Sil:toteilin Of scieffic irreost only gl€it€dg viitmioiito, nonszite, xenotime(Y) Cnut ofwdhsing W wdlin+ qodalltte, colfi$itr" Fairfisl4 Utah Of ecieffic imereotonly on phosphoriteg messdits,frirfieldite U.S.A Crustofwdking Ctor@Ug florcndte4&), monqzirs Mrimatf,t Kear1ta Ofsci€fficiftrc$@ly mcqbondes Altereddolomitic Dolomito,gypsuo, pyrb!, Kovdor Of scientiffcinerct only c{tmdit€s mneE tpnbf'itl.' golalte, gorceuE, KokPeninsrla atrdphoscorit€s tovtortite dmkorolgite,bobi€nit€, Russia Sr-rkfi coflimite,c,hlo,rite talc Co@cimddcafisnAmn(19tr4" Ivldlinietdl (1982)Voloshin€t4f (1991) Solodov aaL (lqtsl\F4orw etal QWr\UFia(1995) ondBcrnhrd et aL (198). ltrmats dthe crmdaliiegrury, fu/aftHy essocid€dwit! Scphosphlt€s in hydroth€rnaland epitlermat aeseanblrg€s, re pired in italics. replacement of these minerals by later zicon, catz- pynhotite, as well as fluorapatite are presentin dolo- pleiite, and pyrochlore resulted in a release of Sc in mite carbonatitesand host phoscorites,generally in amounts sufficient for the onset of juonniite minslali- minoramounts. Active hydrolysis of sulfidestook place zation. The breakdown of rock-forming minerals such in zonesof cataclasticrocks, predominanfly in dolomitic as forsterite and clinohumite resulted in an additional carbonates.This fact is confirmed by the presenceof transfer of Sc to hydrothermal solutions. It should be numerouscavities in mineralizedveins of dolomitic noted thatjuonniite is not present in the rocks that are carbonatite.The cavitieslocally containcorroded relics well away from the clinohumite-bearing altered of sulfidesobut more commonlyare filled with a fine phoscorites. sootymixture of iron andmanganese oxides, phosphates Possible agents of transport of Sc could be SOa2* of Mg andFe, gyps 'm, barite andmagnetite. Such mix- or CO32-,which most likely were present in solutions. turesare not found in cavitiesin zonesof more intense The solubility of carbonates and sulfates of Sc and the circulation of solutions.Owing to the hydrolysisof insolubility of its phosphates under low-temperature sulfides, sulfate anions were transferredto circulating hydrous conditions are well L:nown (Shakhno et el. hydrothermalsolutions, which, accordingto Bulakh & 1976, Borisenko & Polikashina l99l). 5uffidss, mainly [yanikov (1984),were originally eDrichedin CO2.In Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 SCANDIT'M MINERALTZATION. KOVDOR MASSIF. RUSSIA 979 addition, the initial granular fluorapatite is everywhere Acrnqowuencelvmlrs replaced by a fine brown aggregate of hydroxylapatite, which contains2-2.5wt.Valess phosphorus.Taking into We are gratefirl to Victor N. Yakovenchuk Alla N. account these findings, scandium appears to have been Bogdanov4Sergei N. Britvin,LyurlmilaD. Chistyakovq transported in solution from altered phoscorites as a solu- Lyubov I. Konstantinovaand Anna E. Bykova from the ble carbonate or sulfate (or both) and to have precipitated GeologicalInstitute, Kola ScienceCenter, Russian from solutions in the presenceof phosphorusin vuggy Academyof Sciencesin Apatity, Evgeni A. Krasovsky dolomitic carbonatites and their exocontacts. Thus, the andAlexander N. Putilov of the GeologicalSurvey staff wggy carbonatite veins served as a phosphatic barrier of theKovdorsky GOK miningcompany, and Dr. G.N. on the migration paths of scandinm, and this resulled in Eby of the University of Massachusettsat Lowell, for the formation of aunique hydrothermal assemblagewith their help in carrying out field and analltical work. the hydrous phosphateof scandium,juonniils. We thankRobert F. Martin andp. palmel, of McGill The temperature of formation of Sc mineralization University, andG.N. Eby for the constructivereview of can be estimated only approximately. According to the first version of the manuscript.The study was sup- thermometric tests of fluid inclusions in rock-forming ported financially by RussianFoundation for Funda- minerals, phoscorites formed at 690-900'C, and car- mentalInvestigations. bonatitesoat &0J55"C (Kharlamov et aI. l98l). Tt.e upper temperature of postcarbonatite hydrothermal RsreREr.{cFs veins is about 400'C (Bulakh & Ivanikov 1984). The spatial relationships of minerals in the hydrothermal Ar,,nr,n. (1977):Carbonatites, a possible source of scandium indicated by Sc mineralizationin the Fen peralkaline assemblage from mineralized dolomitic veins indicate as complex,southern Norway. Econ. GeoI. 72, 855-859. that juonniite crystallized a.fter kovdorskiteo but before bobierrite. Because these mineral species contain mol- BERNHARD,F., Werrc,n, F., Errnrcrn, K., Teucnn, J. & ecules ofH2O and the loss ofhydration water leads to N{ERBnB,K. (1998):hetulite, ScPOa,a new scandium destruction of their structures, we used results of ther- mineral from the Sryrian and Lower Austrian lazulite mal analyses of kovdorskite and bobierrite to estimate occurrences,Austria- Am. Mineral S3, 625-630. roughly the temperature range ofjuonniite crystalliza- tion. As kovdorskite and bobierrite break down at tem- BoRIsENKo,L.F. (1961): Scandium.Main Featuresof peratures of.23tr and 160"C, respectively, the tempera- Geochemistry,Minzralogy and Gewtic Typesof Deposits. Nauk4 Moscow,Russia (in Russ.). ture of formation ofjuonniite cannot exceed 230oC. Izdatelstvo The occurrence ofjuonniite in the Kovdor phoscorite & Porxasmqa, N .5. (1991): Methodical Recommen' - carbonatite complex is a new type of scanditrm min- dntiow for a PerspecrtveEvaluation of Various Typesof eralization (Table 5). It originated owing to a set of Scandium-ContainingRa'ut Matendl. IzdatelswoMGRE, favorable factors, the most notable being the enrichment Moscow,Russia (in Russ.). of Z- and M-bearing accessoriesin Sc, a spatial coin- cidence of scandium-enriched varieties of phoscorites BoRoDnr,L.S., LAprN,A.V. & Krnnqmmov, A.G. (1973): and a stockwork of late dolomitic carbonatiles affected Rare-Metal-BearingCamaphorires. Izdatelstvo Nauk4 by faults and postcarbonatite solutions, and the insta- Moscow,Russia (in Russ.). bility of Sc-bearing minslsls, sulfides and fluorapatite ( Problemsinthz Min' under hydrothermal conditions. BuLArcr,A.G. & Ivnwmov, V.V. 1984): eralogy and Petrology of Carbonarr'te^r.Leningrad Univ., This study and data from the literature atlest to the Leningrad,Russia (in Russ.). existence of a stable parageneticrelationship between minerals phosphates of Sc and the crandallite-group in DuNAEv,V.A. (1982):Structure of the Kovdor deposit. hydrothermal and exogenic conditions (Table 5). Prob- Geolngyof Ore Deposits4(3),28-36 (in Russ.). ably, hydrous phosphates of aluminum and scandium crystallize in hydrous solutions under similar conditions. Env, G.N. (1973): Scandiumgeochemistry of the Oka It is likely that the occurrence61 glandallite-group min- carbonatitecomplex, Oka, Quebec.Atn. Mineral. 58, erals in low-temperature mineral assemblages can be 819-82s. indicative of potentially increased concentrations of Sc and of the presenceof scandium phosphates. EcoRov,V.C., KAzAKov, A.A., Kezawrsuv.V.V., Mosucnn- & Onormrrs, G.E. (1993):A scandiumrare- The scandium mineralization discovered in the sKy, Yu.A. earth occurrencein Kumir, Gorny Altai. Iarcstia Vazov. Kovdor massif makes it possible to consider phoscorite Geologyand Raarcdka2,43-54 (in Russ.). - carbonatite complexes of alkaline-ultrabasic massifs as potential sources of scandium. Large differentiated KHARLAMoV,Yn.S., KuonvawsBva, G.P., Gnnaxnl, V.K., central-type massifs with carbonatites and clinohumite- KonrxNova, N.G., Mosxervrx, A.A., Snwnormsxava, bearing phoscorites, such as at Kovdoro Vuoriyarvi, S.M. & SnucunovaN.A. (1981):Origin of carbonatitesof Seblyavr, Silkli, and Palaborwa, are the most promising the Kovdor deposit. Geology of Ore Deposits 23, in this respect. 865-880(in Russ.). Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/36/4/971/3447174/971.pdf by guest on 26 September 2021 980 TIIE CANADIAN MINERALOGIST Kocenxo, L.N., KoNoNova, V.A., Onrova, M.P. &Woor:-uv, Suarmo, I.V., SlswsovA,2.N., Ftsoonov,P.I. & Konovnq, A.R.(L995): Allalfue Rocl KuruaneNKo, A.A., BULAKH, A.G., ILyINsKry, G.A., Sor-oDov,N.A., Srosynrve, M.B., Rooronov,V.D., Smvranw, N.F. & Onr.ova, M.P. (1971): Metallogenic Kouamrrsru, G.M. & PHanpHsL,R.I. (1991):A Methodi- Peculiarities of Alkaline Formntions of the Eastem Baltic cal Recommendationto Prognostication,Search and ShieW.lzdatelswo Nedra kningrad, Russia (in Russ.). App rais aI of Sc andiutn D ep os it s. IzdatelswoMGRE, Mos- cow, Russia(in Russ.). Onr-ovn,M.P., Bur-Arcr, A.G., Becpesanov,E.A., Rn\4sKAyA-KoRsarovn,O.M., Nrrmov, E.I., II-ytr{sny, Sunnornq,V.V., VoLosHrN,A.V., PAKHoMovsry,Ya.A., G.A., SsncEEv,A.S. & ABAKUMoVA,N.B. (1965): The Mml'slff Lrsnovrcn, R.P., YerovnNcuur, V.N., PAKHoMovsKy, Volosrmr, A.V., Gonouxro, V.V. & PArcroMovsKy,YA.A. YA.A., BocDANova,A.N. & BRrrvrN,S.N. (1997): (1991):About scandiumnineralization and the first find- Juonniite- a new mineral of scandiumfrom dolomite ing of thorweitite Sc2[Si2O7]in granitic peematitesof the carbonatitesof the Kovdor nassrf. hp. Vser. Mineral. Kola Peninsula.Dokl, Akad. Naak318, 972-976 (in Russ.). Obshthcst.126(4), 8G88 (in Russ.). Murnu, M., Mmrwo, S.,Onr-ervlr, P. & Rwerol R. (1982): Cascanditeandjervisite, two new scandiumsilicates from Baveno,ltaly. Am-Mineral (1,599-603. PoLyAKov,K.I. & PoLszHAEvn,L.I. (1991):Peculiariry of chemical composition and physical propertiesof badde- leyite from Kovdor deposit.1z New Data in the Field of Rare-ElementMineralogy of the Kola Peninsula.Kola ScienceCentre, Russian Academy of Sciences,Apatity, Received August 20, 1997, revised manascript accepted May Russia(4548, in Russ.). 23. 1998. 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