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Rare Earth Elements and their Occurrence in Northern Saskatchewan by C.T. Harper

Harper, C. T. (1987) : Rare earth elements and their occurrence in northern Saskatchewan; in SIM!milry of Investigations 1987, Saskatchewan Geological Survey; Saskatchewan Energy and Mines, Miscellaneous Report"li7 -4.

The steadily growing demand for rare earth bastnasite and xenotime. Monazite, a REE- Y -Th elements (REE) and yttrium (Y) in petroleum phosphate, contains up to 70 percent RED (rare cracking catalysts, the electronics industry, and the earth oxide), 7 percent ThO and 2 percent Y z03. manufacture of super conductors, permanent Bastnasite is a rare earth fluorocarbonate which magnets, ceramics, glass and metal alloys indicates contains up to 75 percent RED and minor Y z03. that these elements are worthy of exploration Xenotime is a yttrium phosphate, which contains up attention. The purpose of this paper is firstly to to 60 percent Yz03 and is more enriched in the illustrate the character, variety and distribution of 'heavy' REE, dysprosium (Dy, atomic no. 66) to REE occurrences in general, and particularly in lutecium (Anstett, 1986). Both monazite and northern Saskatchewan, and secondly to fulfill a bastnasite are 'light' REE enriched. demand from the mineral industry for information on these REE occurrences. Minor ore minerals include apatite, allanite, brockite , crandalite, euxenite and loparite.

The Rare Earth Elements Until recently, monazite was the principal source of REE. It occurs in many geological environments, Rare earth elements, or the lanthanide series, being most prominent in felsic igneous rocks such as constitute a group of 15 elements (16 including granites and pegmatites. Most monazite is yttrium) beginning with lanthanum (atomic no. 57) extracted from heavy mineral beach sands as a and ending with lutecium (atomic no. 71) (Table I). byproduct of sands mined fo r ilmenite, rutile, Although generally more abundant than elements cassiterite, zircon or gold. The principal mining such as gold, silver and uranium (Mason, 1966), REE areas are along the coasts of Australia, Brazil, rarely form distinct minerals in nature, occurring India, South Africa and the United States. instead in trace amounts in over 250 minerals, of which 54 are designated as lanthanide minerals Xenotime generally occurs in the same (Valasov, l 966). environments as monazite. Like monazite, it is a byproduct of placer mining, in particular the tin Despite their relative abundance, there are only placers of Malaysia and China (Anstett, 1986). three major ore minerals for REE and Y: monazite,

Table l - Rare Earth Element Abundance in Chondrites, the Crust and Some Camnon Rocks. Values are i n ppm.

Atomic Element S~ol Average Average Average Average Average No. Chondritesl Crust2 Granites2 Sha les2 Basalts2

57 Lanthan1111 La .30 ± .06 35 55 40 10 58 Cerium Ce .84 ±. 18 70 90 70 30 59 Praseodymi1111 Pr . 12 ± .02 8 10 9 4 60 Neodymi um Nd .58 ± . 13 30 35 30 20 61 Promethi 001 Pm 62 Samarium Sm . 21 ± .04 7 9 7 05 63 Europi1111 Eu .074 .t .015 1.2 1.0 1.4 1. 5 64 Gadolinium Gd .32 ± .07 7 8 6 6 65 Terbium Tb . 049 .t .010 1 1.5 1 0.8 66 Dysprosi um Oy 6 6.5 5 4 67 Holmium Ho . 073 ± .014 l.5 2 1.5 l 68 Erbi1111 Er .21 ± .04 3.5 4. 5 3.5 j 69 Thul i1111 Tm .033 ± .007 0.5 0.06 0.06 .05 70 vtterbi um Yb . 17 ± .03 3.5 4.0 3.5 2.5 71 Lutetil.m Lu . 031 ± .005 0.6 o. 7 0.6 .05

lfrom Haskin et al. ( 1968) 2f rom Krauskopf (1979) - 83 -

Bastnasite occurs in veins and as disseminations in granite dykes which intrude high-grade gneisses of carbonatite intrusions (e.g., Mountain Pass, the Wollaston Domain (Mawdsley, 1957; Watkinson California); quartz veins cutting micaceous schist and Mainwaring, 1976; Assessment File and quartzite (Burundi); epithermal fluorite veins 74Al2-0005, Saskatchewan Energy and Mines, and breccia fillings in Permian sandstones (New Regina). There is mineralogica1 zoning from Fe-Ti Mexico); and associated with iron ore minerals oxides to monazite to minor concentrations of (China). Bastnasite has now replaced monazite as apatite in a zone less than 5 cm thick and the principal source of REE. The Mountain Pass approximately 15 m long. deposit, which contains reserves of }.6 million tons, produces 50 percent of the world's annual REO The J aha la prospect, located 8 km east of Hunter production (Anstett, 1986). The Chinese iron Bay, Lac La Range, occurs in a zoned pegmatite sill deposits may contain as much as }6 million tons intruding amphibolitic metasediments (Mawdsley, RED (ibid.), but these deposits have yet to be 1954; Ford, 1955; Forsythe, 1981; Sabina, 1987). developed. Uraninite is accompanied in this occurrence by monazite, allanite, apatite, zircon and xenotime. ln Canada, REE have been produced as a byproduct Dark brown monazite crystals, up to l cm long, are of uranium mining in the Elliot Lake region associated with massive biotite selvages of the (Anstett, 1986). Other Canadian reserves of REE border zone (Ford, 1955) and are also reported to and yttrium include Highwood Resources Ltd.'s occur in the intermediate phase of the pegmatite beryllium - yttrium - rare earths - niobium deposit (Mawdsley, 1954). Estimates of the volume of at Thor Lake in the Northwest Territories (James, 1986) and a columbium - fluorite - zirconium - beryllium - Y-rich gadolinite deposit near Strange Lake in northeastern Quebec (Hedrick, 1985; Anstett, 1986). A production decision is expected for the Thor Lake deposit by the end of 1987. ~Ir I I Saskatchewan Rare Earth and Yttrium Occurrences I I There are more than 40 reported REE-bearing mineral occurrences in northern Saskatchewan (Fig. l), the majority of which occur in high-grade r-· gneiss terrains surrounding the Athabasca Basin. I They can be subdivided into the following five I types: l) pegmatite-granite association; 2) j metadetrital; }) allanite veins; 4) detrital heavy 1 · mineral sands in the Athabasca Group; and 5) I diagenetic-hydrothermal associated with I unconformity-type uranium deposits. ,..jI

Pegmatite-Granite Association II x I. .. 2 . • 3. Most occurrences in Saskatchewan belong to the • 4. pegmatite-granite type; the majority are believed u 5. to have formed by anatectic processes. They D Phanerozoic consist predominantly of monazite with rare or Athobosca Grot1 p minor xenotime associated with biotite-rich D (Heli kion) segregations in pegmatites or restites of the D Pr,-Athabcuca baumenf enclosing high-grade gneisses. Allanite, apatite, O~ ~-....____!1 0 ._...... _...... 1._,oo 1)0 ._.200,.J ... zircon and uraninite may also be associated with this type of occurrence. Available assays typically Figure 1 - Distribution of reported rare earth element range from 0.008 to 2.0 percent total REO, but and yttrillll occurrences in northern Saskatchewan. south of Alces Lake in the Beaverlodge region, two Occurrence types: 1, pe!Jllcltite-<;1ranite association; 2, monazite-bearing pegmatite occurrences contain up ~tadetrital; 3, allanite veins; 4, heavy mineral layers to 16 percent RED (Robinson, 1955; Assessment in the Athabasca Group; and S, diagenetic-hydrothermal File 74N09-0020, Saskatchewan Energy and Mines, type associated with unconfonnity urani1111 deposits. Regina). Place names ~ntioned in text include: A, Alces lake; AR, Archie Lake; B, Birch Portage; c, Cluff Lake; CB, Two other significant occurrences include Kulyk Collins Bay; CL, Cigar Lake ; CP, Cup Lake; O, Dawn lake; Lake and J ahala, both of which were originally E, Eagle Point; F.F . , Flin Flon; J, Jahala; K, Kulyk discovered as uranium prospects. At Kulyk Lake, Lake; L, Lyle Lake; M, Maurice Bay; ML, Mclean Lake; MR, located 1 km west of Middle Foster Lake, massive McArthur River; N, Nisikkatch-Hoidas Lakes; R, Rabbit monazite occurs in pegmatitlc, graphic and aplitic Lake ; U.C. , Uranium City; and Z, Zoo Bay. - 84 -

REE-bearing minerals present and geochemical calcite, barite, hyalophane (Ba-feldspar), amphibole analyses are not available for the J ahala or Kulyk and pyroxene (Hogarth, 1957). Grab samples have Lake occurrences. given assays of up to 12 percent total REO (Assessment File 74013-000 I, Saskatchewan Energy Several occurrences with interesting mineralogical and Mines, Regina). associations include: l) a monazite-bearing syenitic pegmatite closely Heavy Mineral Layers in the Athabasca Group associated with the Lyle Lake nepheline syenite (MacDougall, this volume); Athabasca Group sandstones and conglomerates contain heavy mineral layers, especially in the 2) beryliferous pegmatites in the Birch Portage dominantly conglomeratic basal section. Detrital area, 50 km west of Flin Flon, some of which zircon, monazite and xenotime have been identified contain accessary monazite (Radcliffe and in some places (e.g., Maurice Bay (Harper, 1978, in Campbell, l 965; Pyke, 1966; Sabina, 1987); and prep.); Cluff Lake (Pagel, pers. comm.); Zoo Bay (No. 1149, Saskatchewan Mineral Deposits Index, 3) a group of radioactive pegmatites in the Cup Regina)); however, these layers remain essentially Lake area which generally contain less uranium untested for REE-bearing paleoplacer deposits. than thorium; uraninite, molybdenite, fluorite and allanite have been identified, as well as niobium-tantalum values (Munday, 1977; Diagenetic-Hydrothermal Type Thomas, 1983). The association of REE and Y with the Athabasca REE occurrences associated with pegmatites are Basin unconformity uranium deposits is only typically found as a result of uranium exploration beginning to be appreciated. For example, strongly due to the radioactivity of thorium in monazite altered clay-enriched Athabasca Group sandstones and/or allanite. As thorium is commonly more above the Mcclean Lake uranium deposits contain abundant than uranium in these occurrences, they up to 10 percent Y, present in masses of xenotime have attracted little attention, and consequently and goyasite in the clay (Wallis et al, 1985). are rarely if ever checked for REE. Xenotime and goyasite are also associated with uranium mineralization in the McArthur River area, located northeast of Key Lake (Hubregtse and Metadetrital Sopuck, 1987). Yttrium geochemical anomalies, ranging from three to seven times background, An ilmenite-monazite occurrence in Archean occur above the Cigar Lake and Dawn Lake uranium granulite facies metasedimentary gneisses at deposits (Clark, l 987), and elevated Y Archie Lake, 30 km east-southeast of Uranium City concentrations exist at the Rabbit Lake, Collins (Fig. 1), is believed to represent a metamorphosed Bay and Eagle Point deposits (Ruzicka, 1986). heavy mineral accumulation (Harper, 1986, 1987). Locally at Cluff Lake and Maurice Bay, REE are Ilmenite, monazite and trace amounts of zircon and progressively enriched along with uranium (Harper, gold occur in layers 0.1 to 10 cm thick within a 5 to l 983a and unpublished data). The association of 6 m thick stratabound zone that has been traced these occurrences with Athabasca Basin over a strike length of 600 m. Radioactive unconformity uranium deposits suggests a potential anomalies along strike from the main occurrence for "unconformity-type" diagenetic-hydrothermal Y suggest the possibility of further extensions to the and REE ore. zone or additional 'heavy mineral' lenses. Assays of material from the main zone range from 0.1 to 15. 7 percent total REO (Assessment Files 7405-0038, Conclusion -0053, and -0059, Saskatchewan Energy and Mines, Regina) and locally TiOz exceeds 17 .0 percent. Rare earth elements occur in diverse geological Several other ilmenite-monazite occurrences exist settings, any of which could contain ore-grade in the surrounding area (Harper, l 983b, 1986). material. The growing awareness of the important Undoubtedly other meta-detrital occurrences exist industrial uses of REE and Y, coupled with a elsewhere in the Saskatchewan Shield. steadily increasing demand, will undoubtedly lead to increased exploration attention. A variety of REE and Y exploration targets exist in northern Allanite Veins Saskatchewan, with a good potential for the discovery of economic concentrations of these A unique group of allanite-apatite veins occur in elements. · the Nisikkatch - Hoidas Lakes area, 40 km northeast of Uranium City (Fig. I). The veins, which cut granulite and retrogressed granulite facies gneisses, are found in a zone up to 10 km long. Mineralogical zoning is common and includes - 85 -

References Hubregtse, J .J. and Sopuck, V. (1987): Alteration paragenesis of the Helikian sandstone and Anstett, T .F. (1986): Availability of rare-earth, Aphebian basement of the Key Lake Mine and yttrium, and related thorium oxides--Market other uranium deposits in the eastern Athabasca economy countries; in A Minerals Availability Basin, Saskatchewan, Canada (abstract); IAEA, Appraisal; U.S. Oep. Interior, Info. Circ. 911 l, Technical Committee Meeting on Uranium l9p. Resources and Geology of North America, Saskatoon, Aug. 3 l to Sept. 4, 1987. Clark, L.A. ( 1987): Near-surface lithogeochemical halo as an aid to discovery of deeply buried James, D.R. ( 1986): Special situation: Highwood unconformity-type uranium deposits, Athabasca Resources Limited developing high-tech special Basin, Canada; J. Geochem. Explor., v28, p 1-84. metals beryllium - yttrium - rare earths - niobium; Richardson Greenshields of Canada Ford, R.B. (1955): Mineralogy of a uraninite­ Limited, Can. Res. Rep., 5p. bearing pegmatit.e, Lac La Range, Saskatchewan; Econ. Geol., v50, p 196-205. Krauskopf, K.B. (1979): Introduction to Geochemistry, 2nd Edition; McGraw-Hill Book Forsythe, L.H. (1981): Geology of the Lac La Co., N.Y., 617p. Range - Hunt.er Bay - Cartier Lake area, Saskatchewan; Sask. Dep. Miner. Resour., Open Mason, 8. (1966): Principles of Geochemistry, 3rd File Rep. 81-1, 20p. Edition; John Wiley and Sons, Inc., N. Y., l 29p.

Harper, C. T. ( 1978): Uranium metallogenic Mawdsley, J .8. (1954): Radioactive, pronouncedly studies: Maurice Bay; in Summary of differentiated pegmatite sill, Lac La Range Investigations 1978, Sask. Geol. Surv ., Misc. district, northern Saskatchewan; Econ. Geo!., Rep. 78-10, p74-83. v49, p616-624.

_ ___ (l 983a): The geology and uranium ____ (1957): The geology of the Middle deposits of the central part of the Carswell Foster Lake area, northern Saskatchewan; Sask. Structure, northern Saskatchewan, Canada; Dep. Miner. Resour., Rep. 26, 49p. unpubl. Ph.D. thesis, Colo. Sch. Mines, T-2587, 337p. Munday, R.J .C. ( 1977): The geology of the Mudjatik (east) area, Saskatchewan; Sask. Dept. ____ (l 983b): Reconnaissance bedrock Miner. Resour., Rep. 168, 25p. geology: Nevins-Forsyth Lakes area (part of NTS 74 O); in Summary of Investigations 1983, Pyke, M. W. ( 1966 ): The geology of the Pelican Sask. Geol. Surv., Sask. Energy Mines, Misc. Narrows and Birch Portage areas, Saskatchewan; Rep. 83-4, p5- l 5. Sask. Dep. Miner. Resour., Rep. 93, 68p.

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- --,-- ( 1987): The Archie Lake rare earth Robinson, S.C. (1955): Mineralogy of uranium element (ilmenite-monazite) showing: an deposits, Goldfields, Saskatchewan; Geol. Surv. Archean heavy mineral placer deposit, Can., Bull. 31, l 28p. northwestern Saskatchewan; Geol. Assoc. Can.I Mineral. Assoc. Can., Joint Annu. Meet., Ruzicka, V. ( 1986): Uranium deposits in the Saskatoon May, 1987, Prog. Abstr., vl2, p52. Rabbit Lake - Collins Bay area, Saskatchewan; in Evans, E.L. (ed.), Uranium Deposits of ____ (in prep.): Geology of the Maurice Bay Canada; Can. Inst. Min. Metall., Spec. Vol. 33, area, Saskatchewan; Sask. Energy Mines. pl44- l 54.

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Valasov, K.A. (1966): Geochemistry and mineralogy Mcclean uranium deposits, northern of rare elements and genetic types of their Saskatchewan; in Sibbald, T. I.I. and Petruk, W. deposits, Vol. 1: Geochemistry of rare elements; (eds.), Geology of Uranium Deposits; Can. Inst. English translation, Israel Program for Scientific Min. Metal!., Spec. Vol. 32, p!Ol-131. Translations, Jerusalem. Watkinson, D.H. and Mainwaring, P.R. (l 976): The Wallis, R.H., Saracoglu. N., Brummer, J .J. and Kulyk Lake monazite deposit, northern Golightly, J.P. (1985): The geology of the Saskatchewan; Can. J . Earth Sci., vl3, p470-475.