Cobalt MINERALS in the HALLEFORS

C anadian M ineral:ogist Vol. 18, pp. 165-171 (1980)

cOBALTMINERALS IN THEHALLEFORS AREA, BERGSLAGEN, SWEDEN: NEW OCCURRENCESOF GOSTTBITE'PARACOSTIBITE' NISBITEAND COBALTIANULLMANNITE

M.A. ZAKRZEWSKI, E.A.J. BURKE eNp H.W. NUGTEREN*' Institute of Earth Sciences,Free University,De Boelelaan1085' 1801HV Amsterdam,The Netherlands

AssrRAcr lagen, a Precambrian metallogenic province' nJrgjtagen is well known for its more than Costibite, paracostibite, nisbite and cobaltian ull' Z,OOOiron deposits and more than 200 base- mannite are found associated for the first time in metal deposits,predominantly of the polymetallic the small Gruv&sen and Gettin Pb Zn{u-Ag de- Ag-Pb--Zn({u) type. The Falun, Sala, Gar- posits, western Bergslagen, central Sweden. A review penberg and Kaveltorp mines are representatlve province is of the Co minerals in the Bergslagen bf ttrere sulfide deposits. Practically all ore given. were probably formed by remobilization They are connected with folded' metamor' from older sulfides by hydrothermal deposits of cobalt of rhyolitic composition solutions during emplacement of late orogenic or phbsed volcanic rocks postorogenic granites. (in Sweden called hiilleflintas whete finely crys- talline, and leptites where more coarse grained). Keywords: costibite, paracostibite, nisbite, cobaltian These rocks and the associatedmetasedimentary ullmannite. cobalt ores, electron-microprobe anal- units were intruded and surrounded by graniter ysis, Bergslagen, Sweden. of at least two generations during the l80G- 2000 Ma Svecofennian folding. The geology of SovrlreRe the Bergslagen province has been summarized (1970) and Grip (1978). A Gruvisen et Geton, deux petits gisements de by Magnusson mined in this region as a Pb-Zn-Cu-Ag situ6s dans le Bergslagen occidental Cobalt ores were (Subde centrale), on trouve pour la premiEre fois by-product of the copper ores. Betweel.lAlZ I'association costibite, paracostibite, nisbite et ull- aira ISOSabout 310 metric tons of metallic Co mannite cobaltifdre. Aprbs r6examen des min6raux were extractedfrom sevenmines (Fig. 1): the de cobalt du Bergslagen, nous proposons comme Gladhammar mine produced 89.6Vo of the total, m6canisme g6n6tigue une remobilisation hydrother- Yena 8.7/o and Tunaberg l.3Va; O.4Vo came pendant en male du Co de sulfures anciens la mise from the HAkansboda, Atvidaberg, Los and place granites post-orog6niques. de tardifs, voire Riddarhyttan mines (Tegengren 1924). Minor Cfraduit Par la R6daction) amounti of Co minerals were also found in several other polymetallic ore deposits. paracostibite, nisbite, ullmannite M ots-clis : costibite, Cobaltite is the main source of Co in all the cobaltifire, minerai de cobalt, analyse !r la mi- mentioned above; it also occurs in small crosonde, Bergslagen. SuEde. mines quantities in the Utii, Brodd and Ingelsby mines' .;Smaltite'chloanthite" ( = skutterudite) is de- INtnooucttoN scribed from Vena and Los, but Welin (1965) showed that the museum specimens from Los within the,framework of a cur- Investigations consist of cobaltite. Linnaeite is noted in Glad' project on the petrology and ore geology rent hammar. where it occurs with cobaltite' car- area of central Sweden (Fig. of the Hlllefors rollite and bravoite. and in Riddarhyttan with discovery of the minerals costibite, 1) led to the cobaltite" skutterudite and several cerium min- paracostibite in the Gruv6sen and and nisbite erals. Glaucodot is known from Hlkansboda in of cobaltian ullmannite in Getdn deposits, and large, perfect crystals that occur with cobaltite two mines are small -Cu-Zn-Pb the Getiin deposit. These in ores. Co-bearing arsenopyrite (7.9 occurrences in western Bergs- Pb--Zn{u-Ag wt. Va Co) has been describ€d from the Los mine (Welin 1965). Safflorite occurs in Tuna- *Present address: U.N.D.P.. B.P. 836. Yaound6, berg. Cameroun. In connection with the presenceof nisbite in 165

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Ftc. 1. Geological map of the Hbllefors area, simplifieil after Magnusson (1925) and Sundius (1923), with location of examples of cobalt mineralization. Inset shows the location of cobalt-bearing deposits in central Sweden and situation of the Hiillefors area. (l) Late orogenic and postorogenic granites, (2) Svecofennian synorogenic granites, (3) slates and greywackes, (4) greenstones, (5) leptites and hiilleflintas, (6) limestones and dolomites.

the Hiillefors area, it is interesting to note the the Bergslagendistrict. Table I presents a sum- Ni minerals of central Sweden. Breithauptite mary of the ore-mineral paragenesesof these was found in Tunaberg (Odman 1933) with deposits. rammelsbergite, nickeline, pentlandite, cobaltite The Get0n mine (Fig. 2) is situated on a and safflorite, in the Sv[rdsjii Zn-Pb-Cu mine small island 8 km east of Filipstad in the west- with Ag, Bi and Mo minerals, and in Kaveltorp ern flank of the Saxi syncline. A magnetite- in Cu-Pb-Zn ores with Bi, Mo, Ag, Au and bearing skarn was developed between the dolo- As minerals. Gersdorffite occurs in the Los mine, mite and leptite unitb that form the border of a and nickelinein Sala.Pentlandite is the common central limestone dome. The sulfides either oc- mineral in Ni mines, where it occurs with pyr- cur in the magnetite ore or form separatebodies. rhotite and chalcopyrite. A cordierite-gedrite quartzite accompanies the magnetite and sulfide ores in the northern part Co MrNsneuzATroNs rN THq Hilnrrons AnEe of the island. This ore-bearing quartzite, which also occurs in other Bergslagensulfide deposits, The discovery of the CoSbS phases in the can be compared with a similar unit in the Getiin and Gruv&sen mines started a search for Falun mine. Production started in 174O,initially Co minerals in about 80 other base-metal de- for iron and later for Cu, Pb and Ag. During posits in the Hiillefors area. Cobalt minerals were short periods of activity before 1918, about found in only six deposits, in addition to two 50,000 tons of magnetite ore were extracted, other localities (Nordmark and G6sborn) de- along with ores containing 650 tons 'of Pb, 50 scribed by Magnusson (1925). Their locations tons of Cu and 40O kg of Ag. As the dumps are marked on the geologicalmap (Fig. 1). All from the last period of production are relatively these Co mineralizations are small and without rich in sphalerite, it is probable that 3'00-600 any economic value, but they constitute an im- tgns of Zn werc also present in the sulfidic portant phenomenon in discussionsof genesisin ores.

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The Gruv6sen deposit (Fig. 3) is located TABLE1. OBEMINERAL ASSEMBLAGES IN CO-BEARING M1NERALIZATION' HALLEFORSAREA about 4 km east of Get6n in the Saxi syncline, which involves slates, greywackes, greenstones, Mineral 1234567891011 dolomites and limestones surrounded by leptites. 0old The mineralization occurs in the dolomites Si lver +++ Al largentm + flanked by sterile limestones, suggestingthat the Bi smuth +{ + carbonates form a local anticline (Magnusson Antimony Galena +t+ tat f 1925). The anticline is truncated to the south by seleniangalena + a post-Svecofenniangranites (1700 Ma: Welin et +++ ++++ l,lurtzi te al. 1977). Ore was excavated from seven mines Troi l ite +t Pyrrhotite during the sixteenth and seventeenth centuries; Pyri te +++ ++ place l',larc asi te + more recent exploitation took from 1906 Mackinawite +t to 1.9'17,and numerous pits and dumps are still Cubanite t+a Chalcopyri te tt++t ++++ in evidence from this operation. The estimated CovelI i te + Stanni te t+ production was about 500 tons of Pb:Zn:Cu in Acanthite + the proportion 11:9:1. The richest deposit was Hessite i Tetradynite the Ling mine in the central part of the car- Bismuthinite -dome. Molybdenite ++++ bonate Judging by the location of the Arsenopyrite ++t dumps, it is assumed that the central storage 0udmundite a Cobaltite t++t+t point of the ores was close to the northern 0ersdorffi te shaft, the Kung Karla mine. There are two types Costibi te ++ Paracostibi te of ore: (1) massive sphalerite with pyrrhotite, Cobaltianullmannite t chalcopyrite and galena and (2) light-colored Nisbite Breithaupti te diopside skarn with rich disseminationsof chal- Nickeli ne Skutterudite copyrite, molybdenite and native bismuth. saffl ori te The Finnfalls mine is a small excavation 2 Tetrahedrite Pyrargyri te +++ km south of Gruvisen. About 250 tons of Cu Pb-Sb-sulfosal t (1) Bi-sul fosal t ore were produced, of two types: rich Cosali te disseminationsof pyrrhotite and chalcopyrite in Galenobismutite greenstone and (2) disseminations with native l4agnetite n t++ Hematite t + bismuth, molyMenite and chalcopyrite, min- Ilmenite t+ Rutile eralogically very similar to the Gruvlsen mine Goethi te ff (Table galena Cassiterite {} 1). The trace-element contents of scheeli te + and sphalerite from both localities are also very 1. 61gylsen,LBng mine (spec. 12f)i 2. Gruv9sen,Torskeback mine; similar. 3. GruvSsen,Dresfall mine; 4. Getbn,stora silver nine (spec. 56C3); 5. Getiin, Koppar+ Norra minei^6. F'innfallsi 7. Nordnark The Nord iron mine oscurs in the Finnshyt- (Magnusson,1925); 8. Nordminei 9. GHsborn(l'lagnusson, 1925); teberg field, 4 km north of Filipstad. The iron 10. Sikfors; 11..Sundsudden (s. l.laesschalck,pers. com.). ores occur in skarns and leptite rocks surrounded by the Filipstad granite. According to Magnus- son (1925) the ore consistsof magnetite with ered by S. Maesschalck (pers. comm. 1'979). accessory pyrrhotite and pyrite; the most in- The geology of the Sikfors mine resemblesthat teresting feature, however, is the occurrence of of the Finnfalls mine. Cobaltite and skutterudite native bismuth. The latter mineral uras found are associatedwith pyrite, pyrrhotite and chal- in samplds from the dumps, as microscopic in- copyrite, which occur together with quartz, clusions in a Co mineralization containing co- chlorite and calcite in gteenstone and in fine- baltite, cobaltian pyrite, linnaeite--corrollite and grained leptite. clinosafflorite (Burke & Zakrzewski in prep.). In the Nordmark mine sulfides occur as dis- DsscntpttoN or (Co,Nr)-S"-S P'nesrs seminations in the Mn-bearing carbonate dome associatedwith the main magnetite skarn ores. Costibite has previously been described from The ore minerals, as described by Magnusson Broken Hill, New South Wales, Australia (1925), are listed in Table 1. (Cabri et al. l97Db), paracostibite from the Red In the Gisborn mine a small cobaltite and Lake area, Ontario (Cabri et al. 1'97Oe) and bismuthinite mineralization was noticed by Mag- from the Guangdong province, China (Anon- nusson (1925) in the magnetite -ores of the ymous 1976), nisbite also from the Red Lake Anders Pers shaft. In Sundsudden.a small man- area (Cabri et al.. l97}c) and from the Festival- ganese mine, disseminatedcobaltite was discov- noe Cu-Sn mine in the Magadan district,

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Frc. 2. Geological map of Getiin island (after Magnusson 1925) and location of mines. (1) Cordierite-gedrite quartzite, (2) lE>tite, (3) skarn, (4) iron ore, (5) limestone, (6) dolomite. Flc. 3. Geological map of Gruvisen (after Magnusson 1925) and location of mines. (1) Postorogenic granite, (2) slate, (3) spilitic greenstone, (4) greywacke, (5) massive greenstone, (6) limestone, (7) dolomite'

U.S.S.R. (Kachalovskaya& Kukoev 1973), and phasesis based on electron-microprobe analyses cobaltian ullmannite from Broken Hill (Cabri itutt" Z; and on the comparison of their et al. 1970a) and from Espeland, Norway (Naik optical properties with those described by Cabri et al. 1976). The present study reports the first ei at. (1gzoa, b, c). Electron-microproh anal- occurrence in which the four minerals are found yses were performed with a Cambridge Instru- together. ments Geoscan (equipped with a LINK energy- The small grain-size and the fine intergrowths dispersive system) and Microscan 9. Natural shown by these minerals prohibited the extrac- and synthetic compounds were used as standards' tion of powder for X-ray-diffraction patterns; Appaient concentrations were ZAF-corrected thus, the identification of the (Co,Ni)-Sb-S with a modified Springer (1967) program and with the Microscan 9 on-line ZAF program. In the Gruv&sen deposit, intergrowths of TABLE2. ELECTR0N-!4ICRoPRoBEANALYSES 0F Co- ANDNi-lillNERALS paracostibite (Figs. 4A and 48) FROI4THE HATLEFORS AREA costibite and attain maximum dimensions of 40 x 40 pm, and Spec. l4ineral Co Ni Fe Sb As S Total always occur on the contacts between chalco- 374 Cobaltite 3),.2 1.2 2.4 - 47.7 19.3 101.8 pyrite and native bisrnuth (see Table I for a 622E Cobaltite 27.7 4.2 2.5 - 44.8 19.2 98.4 12,15 Nisbi te - 17.9 - 74.2 92,1r summary of the mineral assemblage).The som- 37A skutterudi te 18.6 0.9 1.1 - 77.9 - 98.5 positions of minerals are identical; electron- 56C3 Cobaltlan both ullmannite11.0 14.4 2.3 52.7 - 15.7 99.3rt microprobe traverses across the intergrowths 56C3 Costibite 25.6 2,4 0.8 56.8 0.3 14.7 100.6 r2f Costibite 24.2 2,3 2.0 55.0 0.3 15.0 98.8 failed to show any differences. It is easy to t2f Costibite 25.6 1.8 0.6 56,6 0.3 14.4 99.3 their r2f Costibite 25.9 1.6 0.3 56.1 0.4 14.6 98.9 recognize the minerals optically becauseof r2f Paracostibite 23.2 3,1 1.5 56.1 0.2 14.5 98.6 intergrowths. In oil immersion costibite shows a very weak reflection-pleochroism, grey-white r smi-quantitative analysisi lw total due to small grain size !t includes 3.2 vt, % Pb from adjacent galena with a bluish tint to grey-white with a brownish analyses6re reported ln reight r. tint. The anisotropy is distinct, somewhat 37A- Sikforsi 622E- sundsuddenil2J5 - Gruvdsen^Dressfalls ninei 56C3- Getiin,Stora silver mine; l2f - Gruvxsen,Ldng mine. stronger than for chalcopyrite, with reddish-

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brown and dark-grey polarization colors (with exactly crossed nicols), or orange and bluish colors (nicols slightly uncrossed). In contrast. paracostibite has a somewhat higher reflectance and a more distinct reflection-pleochroism, grey-white with a slight bluish tint (in this position almost the same as costibite) to grey- white with a pinkish tint (distinctly lighter than costibite). The anisotropy is distinct, somewhat stronger than for costibite, with the same polarization colors but with more pronounced tints. Cobaltite (Fig. A) has a distinctly higher reflectance; costibite and paracostibite have a more bluish color in comparisogr.The anisotropy of costibite is weaker than that of cobaltite, but paracostibite is more anisotropic than cobaltite. The polishing hardnessesof costibite and paracostibite are similar, higher than for chalcopyrite and lower than for cobaltite. The re- placement of paracostibite by costibite (Fig. 4) is in agreement with the suggestion by Cabri et al. (l970b) that costibite is the lower tem- perature polymorph. Nisbite occurs as small grains (maximum diameter 4 pm) at the contacts between galena and pyrrhotite grains. The mineral is white, shows a reflectance higher than all other phases except native bismuth, and has a very weak reflection-pleochroism and anisotropy, much weaker than for costibite. The polishing hard- ness is higher than for pyrrhotite. The occurrence of nisbite with pyrrhotite is also char- acteristic of the Red Lake (cabri et al. 1970c) and Festivalnoe (Materikov 1977) deposits, in which it is further associatedwith chalcopyrite, galena, arsenopyrite, tetrahedrite and breithauptite. Ullmannite and native bismuth are also present in the Festivalnoe mine (Kachalovskaya & Kukoev 1973). The identification of the (Co,Ni)-Sb-S phases in the Gettin deposit is more difficult becauseof the much smallergrain-size (Fig. aC). Costibite, paracostibite, cobaltian ullmannite and gersdorffite occur as small inclusions in galena. The optical properties of the CoSbS phases are the same as in the Gruvlsen deposit. Cobaltian ullmannite"with Col (Co * Ni) = 43.2 (Table 2), is greyo without pinkish or bluish tints, and isotropic; the reflectance is slightly higher than for costibite, but lower than for paracostibite, in agreementwith the data given by Cabri et al. 4. Textural relations of Co and Ni minerals (1970b). grain gersdorffite (2 Frc. A small of p,m) from Gruv&sen (A, B: spec. 12f)' and Getiin is white and isotropic. with a reflectance slightly (C: spec. 56C3). Drawings after microphoto- higher than for paracostibite and cobaltian ull- craphs. Abbreviations: Bi native bismuth, Cb mannite. The cobaltian ullmannite grains con- cobaltite, Cs costibite, Gn galena, Gf gersdorffite, tain small speCks(1 pm) of a white. weakly Ns nisbite, Pc paracostibite, Sp sphalerite, Ul anisotropic mineral with a much higher reflect- cobaltian ullmannite; black is gangue.

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ance; it was determined as nisbite with the help paracostibite derived their Sb content from na- of electron-microprobe traverses across the tive bismuth or galena. The Co was probably Sxains. derived from chalcopyrite. The well-known pref- erence of cobalt for chalcopyrite and pyrite, Tns OccURRENcE oF Co MTNSRALS and that of nickel for pyrrhotite (Cambel & N BsncslecsN Jarkovsky' 1969), are demonstrated by the pres- Field investigations and microscopic data in- ence of the Co phases'at contacts with chalco- dicate the occurrence of two types of sulfide pyrite, and by the presence of nisbite at pyr- mineralization in the polymetallic ores of rhotite contacts, resPectivelY. western Bergslagen. The older pyrrhotite- The relative rarity of costibite and paracostib- pyrite-galena-sphalerite-chalcopyrite-arsenopy- ite compared with cobaltite is due to two rite mineralization may be regarded as belong- factors: (1) a relatively low concentration of ing to the ooFaluntype", according to the classi' Co, leading to a general paucity of Co min- fication of Magnusson (1970). The younger erals, and (2) the relatively high concentration molybdenite-native bismuth-chalcopyrite(-stan- of As. In most Bergslagen Co deposits cobal- nite) mineralization may be compared with the tite was the only Co mineral to form, provided "Yxsjiiberg-Hdrkentype" of Magnusson(1970). that the Co atoms did not stay trapped in pyrite Discussion of the genesis of the Falun-type or chalcopyrite. The Sb-bearing phases could mineralization is strongly influenced by the pro- only crystallize if. no more As was available. posal of magnesiummetasomatism developed by The many Mo-W and Bi mineralizations in Geijer (1917, 1964) and Magnusson (1925, Bergslagen frequently occur in a spatial rela- 1970). According to this theory, the ore de- tionship with the late orogenic granite, but only posits are introduced into the leptite complex in a few deposits is Co present in this para' by solutions driven from the synkinematic older genesis, suggesting that the granite could not granites. These solutions would also be respon- have been the source of this metal. The distri sible for the formation of the cordierite-gedrite- bution of Co minerals in the Hiillefors area bearing quartzite that frequently ac'companies indicates two other possibilities: (1) remobiliza- the sulfides. Koark (1962) suggestedthat the tion of cobalt from other sulfides of the older ores \rere formed syngenetically, together with Falun type and (2) remobilization of cobalt the volcano-sedimentaryrocks, their sourcebeing from greenstones.fn both cases cobalt would volcanic exhalations or solutions. In this case, have been leached from chalcopyrite or pyrite, the cordierite-gedrite rocks would be the result probably by hydlothermal solutions associated of metamorphism of these volcano-sedimentary with the late orogenic or postorogenic granites. deposits in a later stage. The Yxsjiiberg-Hdrken type of mineralization is apparently related to ACKNowl-EDGEMENTS the late orogenic Svecofennian palingenetic granites and pegmatites (Magnusson 1970, Hiibner Boliden Metall AB kindly gave accessto their 1971, Ohlsson 1979). The ore minerals are material from the Bergslagen area. Professor molybdenite, scheelite, chalcopyrite, native bis- Oen Ing Soen (University of Amsterdam) and muth, sometimeswith bornite, sphalerite, allanite Dr. U. Wiklander (Geological Survey of and fluorite. At Gruvlsen, the CoSbS minerals Sweden) are thanked for the helpful discussions were formed in this type of mineralization. and for the specimens. Electron-microprobe Microscopic observations show that the os- facilities were trnovided by the Free University currence of CoSbS phases is restricted to the and the WACOM, a working group for anal- contacts between chalcopyrite and native bis- ytical geochemistry subsidized by the Nether- muth (Figs. 4A,B); in the Getbn examples,they lands Organization for the Advancement of occur only at tlte contacts of galena with chal- Pure Research(mIO). Dr. C. Kieft (WACOM) copyrite (Fig. C). Microprobe analysesof native carried out some of the analYses. bismuth from Gruvisen show an Sb content of 0.3 wt. /o in occtJnencesdevoid of Sb min- RnrBneNcgs erals, but under the detection limit (0.02 wt. if Sb minerals are present. Similarly, in ANoNvltous (1976): The crystal structureof para- %) (in polished sections from Getiin containing CoSbS costibite. Sci. Geol. Sinica 1976, 227'234 English abstr.). phases and native antimony, the Sb content of Chinesewith galena is below the detection limit, whereas in Cesnr, L,J., Hennrs, D.C., Srrwenr, J.M. & Row- other sections galena contains 0.02-0.13 wt. 7o r.eNo,J.F. (1970a): Willyamite redefined.Proc. Sb. These observationssuggest that costibite and Aust. Inst, Mining Metall.233, 95-100.

Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/18/2/165/3445721/165.pdf by guest on 01 October 2021 COBALT MINERALS FROM HALLEFORS. SWEDEN 171 __, _, & _ (1970b): Costib_ (1970): The origin of the iron ores in (CoSbS), ite a new mineral from Broken Hill. central Sweden and the history of their altera, N.S.W., Australia. Amer. Mineral. 55, lO-17, tions. ,Syer. Geol. Unders, Ser, C 643. _, _, & _ (1970c): para_ Mernnrrov, M.P. (1977): The Festivalnoe deposlt. costibite (CoSbS) and nisbite (Nisbr), new min- In Ore Deposits of the U.S.S.R. III (V.I. Smir- erals from the Red Lake area, Ontario, Canada. nov, ed.). Pitman, New York. Can, Mineral. L0, 232-246, Nex, M.S., GuFFrN, W.L. & Cennr, L.J. (1976): Ceunnr., B. & Jemovsry', J. (1969): Geochemistry (Co,Ni)SbS phases and argentian bou- ol Pyrrhotite ol Various Genetic?ypes. Komen- langerite in galena from Espeland, Norway. skl Univ., Bratislava. Norsk Geol. Tidsskr. 56, 449454. Gtt,rrn, P, (1917): Falutraktens berggrund och 6ovex, O. ( 1933) : Erzmikroskopische Untersu- malmfyndigheter. ,Syer. Geol. (Inders, Ser, C chung der Sulfiderze von Kaveitorp in Mittel- 275. schweden. Geol, Fiiren. Stockholm Fbrh. 55, 563- 6rt. -:- (1964): On the origin of the Falun type of sulfide mineralization. Geol. F6ren, Stoik- OHLssoN, L.-G. (1979): Tungsten occurrences in holm F6rh.86,3-27, central Sweden, Econ. Geol. 74, 1012-1034. Gryl-,E. (1978): CentralSweden (Bergslagen). tr SpnncER, G. (1967): Die Berechnung von Kor- \lineral Depositsof Europe.l. NorthwesiEurope rekturen ftr die quantitative Elektronenstrahl- (S.H.U. Bowie, A. Kvalheim & H.W. Haslam, Mikroanalyse. Fortschr, Mineral. 45, LO3-124. eds.). Inst. Mining Metall., London. SuNoIus, N. (1923): Grythyttef?iltets geologi. ,iver. HiinNnn, H. (1971): Molybdenumand tungstenoc- Geol. Unders. Ser. C 3t2. currencesin Sweden.Sver. Geol, tJnders. Ser. Ca 46. TEceNcnnN, F.R. (1924): Sveriges iidlare malmer och bergverk Sver. Geol. Unders, Ser, Ca 17. Kecserovsxeye, V.M. & Krxorv, V.A. (1973): The first finding of nisbite in the U.S.S.R.iz WnLtN, E. (1965): Two occurrences of uranium in , Investigationson Ore Mineralogy (M.S. Bezs- Sweden, The Los cobalt deposit and the iron ores mertnaya,ed.). Nauka, Moscow (in Russ.), of the Viistervik area. Geol. Fdren. Stockholnt F6rh. 87, 492-508. KoeRr, H.I. (1962): Zur Alterstellungund Ent- stehungder Srrlfiderzevom Typus Falun. GeoI. -, Gonurscnrv, R. & Luxorcinpn, P.H. Rundsch.52, 123-L46. (1977): Rb--Sr dating of rocks in the Viirmland granite group in Sweden. Geol. Fdren, Stockholnt IVf,acNussoN,NJI. (1925): Berggrundeninom de F6rh, 99, 363-367. centraladelarna av FilipstadsBergslag. persbergs Malmtraktsmalmfyndighetsr. Kungl. Kommerkol- (Jnders. legium& Sver.Geol, Beskr,6vermineral- Received December 1.979, revised manuscript ac- fyndigheter2, l-231, 459464, cepted, February 1980.

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