This document is part of a larger publication and is subject to the disclaimers and copyright of the full version from which it was extracted. Information on purchasing the book, and details of other industrial minerals, as well as updates and copyright and other legal information can be found at: http://www.dpi.nsw.gov.au/minerals/geological/industrial-mineral-opportunities RARE EARTH ELEMENTS Potential and Outlook in the Earth’s crust than silver, gold or platinum, while cerium, yttrium, neodymium and lanthanum are more New South Wales has excellent potential for common than lead. commercial deposits of rare earth elements, principally The elemental forms of REE are iron-grey to silvery in trachyte intrusions of Mesozoic age. The Toongi lustrous metals (Harben 1999). Typically, they are soft, prospect (Toongi) (Figure 22), which is one of malleable and ductile, and usually reactive (rapidly numerous intrusions in the central west of New South forming rare earth oxides), especially at higher Wales, is a potentially world-class source of rare earth temperatures or when finely disseminated. REE are elements. This intrusion is about 24 km south of never found as free metals in rocks. They typically Dubbo and consists of hydrothermally altered alkali occur as mixtures of various REE-bearing minerals trachyte with anomalous rare metal and rare earth and require mineral separation from each other for elements, principally zirconium oxide, niobium/ commercial use. tantalum oxide and yttrium oxide. Bastnaesite, (Ce,La)(CO3)(OH,F); xenotime, YPO4; and Beach placers along much of the coast north of Sydney have heavy mineral assemblages that are dominated monazite, (Ce,La,Nd,Th)PO4.SiO4 are the three most by rutile and zircon, and minor amounts of monazite. economically significant minerals of the more than These deposits are largely depleted, uneconomic or not 200 minerals known to contain essential or significant accessible. The rare earth potential of heavy minerals REE (Christie et al. 1998). Bastnaesite and monazite sands deposits in the Murray Basin, which have small are sources of light REE and account for 95% of REE proportions of monazite and xenotime, has yet to be currently used (Harben & Kuzvart 1996). Xenotime fully assessed. is a source of the heavier REE and yttrium. Monazite is also the principal ore of thorium, containing up to 30% thorium. Together with small amounts (up to about 1%) of uranium, thorium imparts radioactive Nature and Occurrence properties to the monazite. The rare earth elements (REE) are the 15 lanthanide In 2004, global production of rare earths was about elements with atomic numbers 57 to 71 (Christie 102 000 tonnes, mainly from bastnaesite and monazite et al. 1998). In order of increasing atomic number, deposits, some 90 000 tonnes of which came from they are lanthanum (La), cerium (Ce), praseodymium China (Hedrick 2005). Other producers of REE (Pr), neodymium (Nd), promethium (Pm), samarium included Russia, India, Malaysia and Sri Lanka. Global (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), resources of rare earths are estimated at 88 million dysprosium (Dy), holmium (Ho), erbium (Er), thulium tonnes (about one third held by China), primarily in (Tm), ytterbium (Yb) and lutetium (Lu). Yttrium (Y), bastnaesite and monazite. Hedrick (2005) concluded scandium (Sc) and thorium (Th) are generally included world rare earth resources are very large compared to with the REE as they occur with them in minerals and their expected demand. have similar chemical properties. REE are classified into two groups: light REE or cerium group (lanthanum to europium) and the heavy REE, Deposit Types comprising gadolinium through lutetium, as well REE minerals occur in a diverse range of igneous, as yttrium and scandium. The light REE are more sedimentary and metamorphic rocks (Sawka et al. abundant than the heavy REE. 1990; Harben & Kuzvart 1996; Jones et al. 1996; Christie et al. 1998). Their principal geological The term ‘rare earths’ was proposed in 1794 (Christie environments are summarised below. et al. 1998). The term ‘rare’ was used because when they were found they were thought to be present in 1. Carbonatites: carbonate-rich rocks of magmatic the Earth’s crust in only small amounts, and ‘earths’ origin are commonly associated with major faults, because as oxides they have an earthy appearance. lineaments and explosive volcanism. Typically Despite their name, the REE are each more common the last magmatic stage in alkaline–carbonate 150°00’E TWEED HEADS 155°00’E BYRON BAY TENTERFIELD N LIGHTNING RIDGE MOREE INVERELL GRAFTON 0 100 30°00’S kilometres 30°00’S NARRABRI COFFS HARBOUR ARMIDALE REFERENCE TAMWORTH Rare earth occurrence - monazite Rare earth occurrence - excluding monazite NYNGAN PORT MACQUARIE GILGANDRA STUDY AREA SCONE DUBBO Toongi deposit MUDGEE NT NEWCASTLE Qld WA PARKES SA NSW ORANGE BATHURST Vic. Tas. 150°00’E 155°00’E 2005_05_0109 Figure 22. Rare earth element occurrences in New South Wales, excluding mineral sands complexes (e.g. syenites, nepheline syenites and and loparite, (Ln,Na,Ca)(Ti,Nb)O3, form as nephelinites). Bastnaesite-bearing carbonatite is magmatic deposits in the host igneous rocks, and the world’s main source of REE. Examples of REE- as metasomatic deposits in veins, stockworks and bearing carbonatite deposits include Bayan Obo in irregular replacement zones. Examples include the Inner Mongolia, China; Mountain Pass, California; Kola Peninsula, Russia; and the Brockman deposit, and the Mineral Hill district, Idaho–Montana. Western Australia. 2. Beach placers containing detrital REE minerals 4. Iron–REE deposits, perhaps the largest being the of high specific gravity, principally monazite and Olympic Dam (South Australia) hematitic granite xenotime. These minerals are extracted from beach breccia-style (IOCG) deposit. This is a very large placers that are mined primarily for their rutile, deposit, in the order of several thousand million zircon and ilmenite contents. Examples include tonnes, that consists of disseminated chalcopyrite, eastern and western Australia; Florida and Georgia bornite and chalcocite accompanied by gold, in the USA; South Africa; India; and Sri Lanka. uranium, silver, barium, REE and fluorine minerals 3. Peralkaline syenitic and granitic igneous rocks are (Christie et al. 1998). Extremely fine-grained characterised by the occurrence of alkali amphibole monazite and bastnaesite are the most common and pyroxene minerals. REE minerals, principally REE minerals at Olympic Dam, which contains eudialyte, Na(Ca,La)2(Fe,Mn,Y)ZrSi8O22(OH,Cl)2, 0.2% La and 0.3% Ce. 5. Pegmatites, hydrothermal quartz and fluorite veins hosted by hydrothermally altered trachyte. The deposit of various origins. Examples include Northern contains a resource of 50 million tonnes at 4400 ppm Territory, Australia (pegmatites); Karonge, Burundi Nb2O5, 270 ppm Ta2O5, 1240 ppm Y2O3, 110 ppm Ga, (hydrothermal quartz); and Naboomspruit, South 350 ppm HfO2, 900 ppm REE and 1.03% ZrO2 (Aztec Africa (fluorite veins). Resources Limited 2005). 6. Skarn deposits (not associated with carbonatites), which include the Mary Kathleen U–REE–Th skarn, Queensland (now mined out). This deposit New South Wales Occurrences contained REE minerals hosted in uraninite, apatite In the central western part of New South Wales, and allanite developed in garnet-bearing calcsilicate mainly north of Rylstone (near Mudgee) and south of rocks near an alkali granite intrusion. Dubbo (Figure 22), there are numerous Mesozoic sills, 7. Residual laterites enriched in REE that formed by laccoliths, dykes and flows (Warren et al. 1999). They intense subtropical weathering of REE-rich alkaline range in composition from basalt to alkali diorite to complexes. These deposits occur predominantly as trachyte, syenite and phonolite. The intrusions appear mineral assemblages of goethite, hematite, aluminium structurally controlled and are aligned along large- hydroxides, kaolinite minerals and quartz, and scale lineament sets. In New South Wales, trachyte typically contain 10% to 25% rare earth oxides (REO). intrusions appear to have the greatest potential for 8. Residual deposits of REE-bearing clays, termed ionic commercial occurrences of REE. or ion-adsorption type ores, develop in association The Toongi prospect (Toongi), which is about 24 km with weathered granites. Ion-adsorption ores south of Dubbo (Figure 22), is a small, altered are only known from China (Long Nan, Yianxi, alkali trachyte intrusion of Triassic age containing southern China). Rare earth cations released during anomalous rare metal and rare earth elements weathering of granites were adsorbed by kaolin and (Chalmers 1999; Alkane Exploration Ltd 2004). various aluminosilicates. They have grades of about Hydrothermal alteration involving significant 1% REO and are characterised by very low cerium carbonate, chloritic, potassic and argillic alteration has content and a rare earth content that is rich in modified the Toongi prospect (Downes 1999). The REE samarium, europium and terbium, or yttrium. mineral assemblage is very fine-grained and includes bastnaesite, zirconium silicate, yttrium silicates and niobium–tantalum silicates. Main Australian Deposits Toongi, also known as the Dubbo Zirconia Project, has Australia was formerly the world’s largest producer of resources of 73.2 Mt @ 1.96% ZrO2, 0.04% HfO2, 0.46% monazite, almost entirely from beach placer deposits Nb2O5, 0.03% Ta2O5, 0.14% Y2O3 and 0.745% total REO in New South Wales, Queensland and Western (Alkane Exploration Ltd 2004). Feasibility studies Australia (Harben & Kužvart 1996). There has been envisage production of 200 000 tonnes per annum of no commercial production of monazite from those ore to produce 3000 tonnes of zirconium, 600 tonnes sources since 1995 (ABARE 2001). There are several of niobium and tantalum and 1200 tonnes of yttrium– deposits in Western Australia, the Mount Weld deposit rare earth products. and Brockman deposit (see following discussion). Lateritic nickel, cobalt and scandium resources have Production has yet to begin at either deposit (late 2005). been identified at Lake Innes, near Port Macquarie Mount Weld, Western Australia, is a major REE (Figure 22) (Douglas McKenna & Partners Pty Ltd deposit that is developed in laterites formed on 2003). Serpentinite complexes occur in a Permian fault a carbonatite diatreme of Palaeoproterozoic age zone in Silurian–Devonian rocks. Locally, over the (Fetherston 2002). REO contents up to 40% have been serpentinite complexes, laterites, containing weathered found in the laterites. Mount Weld has resources serpentinite, saprolite, limonitic clay and hematite of 7.7 Mt at a grade of 11.9% rare earth oxides, clay, range in thickness from 10 m to 30 m. Scandium which represents about 917 000 tonnes of rare earth tends to occur in the upper part of the lateritic profile, oxides (Lynas Corporation Ltd 2002, 2003). Mining whereas cobalt and nickel are found in the middle operations began in mid 2007. and lower parts of the profile. The deposits contain The Brockman deposit, Western Australia, is a 15.7 million tonnes of nickel at 1.46% nickel, 0.09% potential source of tantalum–niobium and heavy REE cobalt and 41 ppm scandium. (Castor 1994). The REE occur as very fine-grained Alkali pyroxenite rocks from the Staurolite Ridge minerals disseminated in metamorphosed rhyolitic tuff intrusion, Broken Hill, contain altered ultrabasic rocks with high (about 35%) granoblastic carbonate in applications such as cigarette lighters, miners’ safety (Barron 1978). The potential in New South Wales lamps and automatic gas-lighting devices. for carbonatite-hosted REE minerals, however, is Scandium is used mainly as a component of unknown. There may be some potential for REE aluminium alloys in baseball and softball bats; as deposits in A-type granites, and also A-type volcanic alloys, compounds and metals in metallurgical rocks (L.M. Barron pers. comm., 2004). A-type research; sporting goods equipment; semi- granites are highly evolved granites in which fluids conductors; and speciality lighting (Hedrick 2005). enriched in REE, elements such as Nb, Ta, Zr, Hf, Th, U Overall, scandium consumption is very small. and Y, and volatiles such as F, P and CO2, accumulated Yttrium is primarily used in lamp and cathode late during their formation (Sawka et al. 1990). In New phosphors and lesser amounts in structural South Wales, A-type granites are associated with the Bega Batholith and Wyangala Batholith, and A-type ceramics and oxygen sensors. volcanic rocks with the Comerong and Boyd volcanic complexes (Chappell et al. 1991). Economic Factors Several very large deposits, including Mianing in Applications China, the Mount Weld deposit in Western Australia Rare earths have numerous, diverse, highly specialised and the Dubbo Zirconia Project, have yet to be applications (Christie et al. 1998; Hedrick 2005). The fully developed. Long-term demand for monazite is largest use of rare earth oxides is in mixed forms, expected to increase because of its abundant supply principally in petroleum fluid-cracking catalysts and in and its recovery as a low-cost by-product of mineral rare-earth phosphors for television, X-ray intensifying, sands mining. and fluorescent and incandescent lighting. These forms There is an expanding market for rare earths. Their are listed below. use in automobile pollution catalysts, permanent • Globally, about 35% of REE are used as catalysts, magnets and rechargeable batteries, should increase mainly in the refining of crude oil to improve (Hedrick 2005). Strong demand for cerium and cracking efficiencies and in automobiles to improve neodymium for use in automobile catalytic converters oxidation of pollutants. and permanent magnets is expected to continue over • Some 30% of REE are used in the glass and the next five to ten years. Future demand is likely for ceramics industry as glass-polishing compounds, rare earths in rechargeable batteries, fibre optics and decolourising agents, UV absorbers, colouring various medical applications. Long-term growth is agents, in optical lenses and glasses, and additives expected for rare earths in magnetic alloys for such to structural ceramics — such as stabilised zirconia uses as electric generators and air conditioners. and silicon nitride. • About 30% of REE are used in metallurgy as an alloying agent to desulphurise steels, as a References nodularising agent in ductile iron and as lighter ABARE 2001. Australian commodity statistics 2001. flints. REE are also used as alloying agents Australian Bureau of Agricultural and Resource Economics to improve the properties of superalloys and (ABARE), Canberra. magnesium, aluminium and titanium alloys. Alkane Exploration Ltd 2004. Annual Report 2004. Other uses of REE include lasers, microwave applications, www.alkane.com.au alloys, computer memory and specialised ceramics Aztec Resources Limited 2005. Latest News. (Harben & Kužvart 1996). Rare earths enable glass fibres www.aztecresources.com.au to transmit information over long distances without booster stations. Samarium–cobalt batteries have largely Barron B.J. 1978. Unpublished petrological report No. replaced more expensive platinum–cobalt batteries. 78/22: petrographic features of alkali pyroxenite rocks from the Staurolite Ridge intrusion Broken Hill N.S.W. Mischmetal, an alloy composed of Ce, La, Nd, Pr, Sm, (in conjunction with mapping of the Pinnacles sheet by Tb and Y and iron, about 5%, is a component (about R. Brown). Geological Survey of New South Wales, Report 25%) of nickel-hydride batteries and is replacing nickel– GS1978/227 (unpubl.). cadmium batteries in portable electronic equipment. Castor S.B. 1994. Rare earth minerals. In: Carr D.D. ed. Mischmetal is pyrophoric, and when scratched it gives Industrial rocks and minerals, 6th edition, pp. 827–839. off sparks capable of igniting flammable gases (Christie Society for Mining, Metallurgy, and Exploration, Inc., et al. 1998). This property enables mischmetal to be used Littleton, Colorado. Chalmers I. 1999. Dubbo zirconia project. Minfo—New Hedrick J.B. 2005. Rare earths. In: United States Geological South Wales Mining and Exploration Quarterly 62, 38–40. Survey. compiler. Mineral Commodity Summaries 2005, Chappell B.W., English P.M., King P.L., White A.J.R. & pp. 132–133. United States Department of the Interior. Wyborn D. 1991. Granites and related rocks of the Lachlan Jones A.P., Wall F. & Williams C.T. eds. 1996. Rare earth Fold Belt. 1:250 000 scale map, Bureau of Mineral Resources, minerals: chemistry, origin and ore deposits. Chapman and Geology and Geophysics, Canberra, Australia. Hall, London. Christie T., Brathwaite B. & Tulloch A. 1998. Mineral Lynas Corporation Ltd 2002. Lynas doubles rare commodities report 17 — rare earths and related elements. New earth resource estimates for Mt Weld. Announcement to Zealand Institute of Geological and Nuclear Sciences Ltd. Australian Stock Exchange, 9 May 2002. Douglas McKenna & Partners Pty Ltd 2003. Final report on Exploration Licences 4964, 5185, 5135 Lake Innes, Lynas Corporation Ltd 2003. Lynas Corporation Ltd: an N.S.W. Nickel/cobalt/scandium laterite project. Report emerging diversified resources company with a special link prepared for Jervois Mining Limited. Geological Survey of to China. AGM 26 November 2003. New South Wales, File GS2003/312. (unpubl.). Sawka W.N., Heizler M.T., Kistler R.W. & Chappell Downes P.D. 1999. Mineral occurrences. In: Meakin N.S. 1990. Geochemistry of highly fractionated I- and S-type & Morgan E.J. compilers. Dubbo 1:250 000 Geological granites from the tin–tungsten province of Western Australia. Sheet SI/55–4, 2nd edition. Explanatory Notes, pp. 396–426. In: Stein H.J. & Hannah J.L. eds. Ore-bearing granite systems: Geological Survey of New South Wales, Sydney. petrogenesis and mineralizing processes, pp. 161–179. Fetherston J.M. 2002. Industrial minerals in Western Geological Society of America, Special Paper 246. Australia: the situation in 2002. Geological Survey of Warren A.Y.E., Barron L.M., Meakin N.S., Morgan E.J., Western Australia, Record 2002/12, 38. Raymond O.L., Cameron R.G. & Colquhoun G.P. 1999. Harben P.W. 1999. The industrial minerals handybook, 3rd Mesozoic igneous rocks. In: Meakin N.S. & Morgan E.J. edition. Industrial Minerals Information Ltd, London. compilers. Dubbo 1:250 000 Geological Sheet SI/55–4, 2nd Harben P.W. & Kužvart M. 1996. Industrial minerals: a edition. Explanatory Notes, pp. 313–328. Geological Survey global geology. Industrial Minerals Information Ltd, London. of New South Wales, Sydney.
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