Rare Earth Elements
Rare earth elements (REE) are relatively abundant in the earth’s crust, but discovered economic concentrations are less common than for
most other ores. Rare earths can be divided into light rare earth elements (LREE) which include La, Ce, Pr, Nd and Sm, and heavy rare earth
elements (HREE) which include Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu plus Y.
World resources of LREE are constrained primarily in carbonatites, LREE-bastnäsite and monazite. Bastnäsite deposits in China and the
United States constitute the largest fraction of the world’s rare-earth economic resources. Monazite deposits in Australia, Brazil, China,
India, Malaysia, South Africa, Sri Lanka, Thailand and the United States constitute the second largest segment. The latter are found
in paleoplacer and recent placer deposits, sedimentary deposits, veins, pegmatites, carbonaties, and alkaline complexes. Alkali igneous
intrusions in the Lovozero and Khibina Massifs in Russia are also highly enriched in REE, Nb and Ta.
A large portion of HREE is found in xenotime and monazite which occur in a wide variety of geologic environments. These include alkaline
granites, hydrothermal deposits, laterites, placers, and vein-type deposits. A significant portion of HREE is associated with weathered
clay deposits, yttrium-bearing minerals in apatite-magnetite-bearing rocks, deposits of niobium-tantalum minerals, non-placer monazitebearing deposits, sedimentary phosphate deposits, eudialyte-bearing deposits and some uranium ores. Undiscovered REE resources are
thought to be very large relative to the expected demand1. Rare earth elements are ranked as the highest mineral raw materials of critical
concern, given uncertain future supplies and their importance to advanced industrial economies2,3.
The demand for rare earth elements has increased substantially owing to their unique physical, chemical and light-emitting properties. They
are exploited in a range of new technologies along with elements such as Y, Nb, Ta, Zr, Hf and Sc with which they are intimately associated
in many deposits. Nd, Dy, Eu, Tb and Y are now considered “critical” rare earths in terms of their importance to the clean energy
economy and the risk of supply disruption.
Demand for the rare-earth materials has grown more rapidly than that for commodity metals such as steel and in the new developing
market segments Dy, Nd and Pr account for 85% of rare earths used4.
Rare Earths Application in Clean Energy
Rare earths are becoming vital to some fast growing businesses in clean energy.
New generation wind-powered turbines use NdFeB/DyTb permanent magnets.
This critical component gives greater magnetic field strength and higher coercivity
(resistance to becoming demagnetized) than other magnets. The use of rare
earths in permanent magnets considerably reduces the size and the mass of the
generator. Similar magnets are also used in motors for hybrid vehicles, hard disk
drivers and many other electronic applications. Electric car motors require up to
200g of Nd and 30g of Dy. Wind turbine generators can contain one tonne of
Nd per megawatt installed capacity4.Nd demand is currently third after Ce and La
with an increasing forecast deficit for this element along with Tb and Dy (Fig. 1).
Nd magnet cube
Organic blue emitting diode
Rare earth permanent magnets are the largest consumer of REE accounting for
39% of the production (Fig. 2) .The next largest REE consumers are catalysts
(19%) and metal alloys (18%). About 12% of LREE is used for polishing, TV and
computer monitors, mirrors and microchips. A total of 10% of the LREE are used
in the glass industry. Lanthanum, for example, increases the refractive index of glass and is used in camera lenses.
The phosphorescent properties of rare earths, including Y, are heavily exploited in the production of energy-efficient compact fluorescent lamps
(CFL) and light emitting diodes (LED). The new generation of organic light emitting diodes (OLED) uses rare earths (Eu, Tb, Tm) to produce
transparent or surface emitting flat panel displays. The colour of the emitted light can be tuned by changing rare earth ion concentration5,6.
Rare earths are also added to ceramic glazes for colour control7. Barium titanate powder alloyed with REE is used in electronic applications.
Yttrium is used to make ferrites for high frequencies and to stabilize zirconia in oxygen sensors8.In 2008 7000 t of REOs was used in this
category, of which yttrium oxide accounted for 53 % and the remainder being oxides of La, Ce, Nd and Pr.
Rare earths are widely used in medical technology. For example, Gd-based compounds are used as a contrast agent to image tumours
with MRI (Magnetic Resonance Imaging) and the MRI uses REE magnets9. Erbium yttrium aluminum garnet (Er:YAG) lasers are used in
dermatology for skin resurfacing to remove wrinkles.
The unique magnetic properties of Gd may be used in future refrigeration technology. These refrigerators do not require ozone-depleting or
hazardous substances and reduce electricity consumption by up to 15 per cent due to higher energy efficiency10. A thulium-doped lutetium
yttrium aluminum garnet (Tm:LuYAG) laser is used in meteorology to measure wind speed and direction, pollution and moisture.
Promethium occurs naturally in minuscule amounts11, however, it can be produced by bombarding neodymium-146 with neutrons. Promethium
can be used in nuclear powered batteries which use beta particles, emitted by the decay of promethium, to induce a phosphor to emit light. This
light is then converted into electricity by a device similar to a solar cell. This type of battery could provide power for up to five years12.
Japan and the USA are two of the major countries which import REE for their high-tech industries. Together they imported 34000 tonnes of
REE compounds and metals in 2009. These two countries were followed by Germany (8200 tonnes), France (7000 tonnes) and Austria (4500
tonnes) in 2009. China accounted for 97% of the REE supply in 2010. In recent years China has constrained the export of un-beneficiated
REE preferring to export finished products9. China also plans to reduce illegal mining of REE and introduce stricter environmental regulations
concerning REE production. This has boosted the price for REE which has, in turn, made mines outside China more economically viable.
Africa, Australia, Canada13 and Greenland have the biggest potential for filling the REE deficit. As one of the biggest importer of rare earths
Japan had already started to negotiate supplies of rare earths from India and Vietnam14. Projects like Steenkampskraal (GWMG, South
Africa)15, Zandkopsdrift (Frontier Rare Earth, Southern Africa), Mt Pass (Molycorp Inc., USA), Bear Lodge (Rare Elements Resources, USA),
Mt Weld (Lynas Corp, Australia), Kvanefjeld (Greenland Minerals and Energy Ltd, Greenland), Dong Pao (Vimico Rare Earth Co, Vientnam)
and other projects will assist to meet the future demand for predominantly light rare earths. Strange Lake (Quest Rare Minerals, Canada)16,
Nechalocho (Avalon Rare Metals, Canada)17, Kvanefjeld (Greenland Minerals and Energy Ltd, Greenland), Tanbreez (Tanbreez Mining
Greenland, Greenland)18, Nolans (Arafura Resources, Australia)19, Browns Range (Northern Minerals20) and Dubbo (Alkane Resources,
Australia) are promising heavy rare earth projects. The deficits for HREE will however, remain significant.
Global Demand and Supply of REO for 2014 (+14%)
Supply REO tonne
Fig. 1.Global demand and supply of REO for
2014 (± 14%)(IMCOA).
Ce, La, Nd, Pr. Demand driver are tighter NOx and SO2 standards. Used as fluid
cracking catalysts for heavy oils and tar sands.
Ce, La, Nd. Cerium cuts down transmission of UV light;
La increase glass refractive index for digital camera lens.
Ce, La, Nd. Mechano-chemical polishing powders for TVs, Computer monitors,
mirrors and (in nano-particulate form) silicon chips.
La, Ce, Pr, Nd. Hybrid vehicle batteries. Hydrogen absorption alloys for rechargeable
Nd, Pr, Sm, Tb, Dy. Drivers for computers, mobile phones, mp3 etc. Hybrid vehicle
electric motors. Wind turbines.
Eu, Y, Tb, La, Ce. LCDs, PDPs, LEDs. Energy efficient fluoroscent light/lamps.
Eu, Y, Tb, La, Ce. LCDs, PDPs, LEDs. Energy efficient flourescent light/lamps.
Er, Y, Tb, Eu – Fiber Optics. Pm – miniature nuclea batteries.
Lu – single crystal scintillator. Tm – Medical Image Visualisation.
Demand REO tonne
Fig. 2.Pie chart of global rare earth demand in 2008 by application (adapted from USSG Scientific Investigations Report 2011–5094).
Rare Earths Analysis
For many years chondrite normalised plots of the REE have been used in petrogenesis (Fig.3). A europium anomaly is generally an indication
that a rock or the parent from which it was derived has fractionated plagioclase or a mineral into which Eu has partitioned. During magma
crystallization in a reducing environment divalent Eu2+ preferentially incorporates into plagioclase substituting for Ca2+. A plagioclase cumulate will
have a positive Eu anomaly whereas the residual magma, from which it fractionated, a negative anomaly. Large positive Eu anomalies occur in
the most felsic rocks which also have a high Ba content and are severely depleted in HREE. A negative Eu anomaly is a signature of post-Archean
sediments21. In addition to europium, one can observe cerium in two different states: soluble Ce3+ can be oxidised by atmospheric oxygen to less
soluble Ce4+. The presence of a Ce anomaly can be used to determine redox conditions in marine sediments like carbonates and phosphates22.
La Ce Pr Nd
Light REE (LREE)
Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Heavy REE (HREE)
Fig 3. a) REE Chondrite plots of various rocks; b) chondrite
plot of Pb-Zn ore with positive Eu anomaly, which is
associated with Pb-Zn sulphides, New Brunswick, Canada
(Graf23 et al, 1977); c) chondrite of Cu-Zn of footwall with
negative Eu anomaly with enriched heavy REE (“birdwing
profile”) in rocks below the ore (Schade et al, 1989).24
Lanthanum/gadolinium (La/Gd), as a measure of LREEs/HREEs, plotted against Eu/Eu* (measured europium divided by europium calculated from
interpolation between samarium and gadolinium) is also helpful in the classification of REE deposits and the interpretation of their origin (Fig. 4).
1A - Mountain Pass Bastnäsite;
1B - Mountain Pass monazite;
2 - Kangankunde REE-rich carbonatite;
3 - Kizilçäoren REE-rich carbonatite; 4A, 4B - Salitre II perovaskite and anatase,
5 - Mount Weld carbonatite;
6 - Maicuru REE-rich carbonatite;
7 - Bayan Obo ore;
8 - Pea Ridge breccia;
9 - Mineville apatite;
10,11 - Western and Eastern Australiaplacer monazite;
12 - South China placer monazite; 13 - Florida placer monazite;
14 - Brazil placer monazite;
15 - Malaysia placer xenotime;
16 - Strange Lake peralkalineigneous HREE deposits;
17 - Kipawa Lake eudialyte;
18 - Bokan Mountain peralkalineigneous HREE deposits;
19,20 - JabalSa’id and JabalTawlahperalkaline igneous REE deposits;
21 - Crescent Peak vein deposit.
Techniques for Rare Earths Exploration
Most of REE deposits are restricted to areas underlain by Precambrian rocks, which have recognizable features and can be identified by aerial
photography. However, this approach may not be suitable for complexes, which occur in clusters (Mt Weld, Australia) or linear belts (AraxáCatalão, Brazil). Owing to the presence of U and Th in REE deposits, surface or airborne radiometric surveying can be used quite successfully.
Placer deposits however, produce weak radiometric signatures so due care must be exercised. Geophysical methods can be used for buried
mineralisation, but the effectiveness depends on the anomalous density as well as the magnetic susceptibility of the deposit and the associated
rocks. Geochemical surveys using stream sediments, water and soil are used widely to identify REE host rocks. Biogeochemistry can be useful
in identifying REE deposits below cover. Trenching and pitting by heavy equipment may also be useful for poorly exposed deposits.
Using several methods of exploration increases confidence in the results and helps data interpretation. A HREE deposit in Strange Lake in
Canada was found using regional lake water, a sediment survey and tracing of glacially transported boulders, which were found up to 20
km from the source22.
Mt Weld REE Deposit,
Photo courtesy of Lynas Corp Ltd
Kanyika Multielement deposit,
Malawi. Photo courtesy of Globe
Metals and Mining Ltd.
Kvanefjeld REE and Multielement deposit, Southern Greenland.
Photo courtesy of Greenland Minerals
Methods of Analysis
Whether you are using REE as indicators or exploring for REE deposits using soil, rock chips or drill core you need to choose an appropriate
analytical method. The HREE, Y, Zr, Hf, Nb and Ta are commonly hosted by refractory minerals that may not be completely digested by an acid
digestion. Fusion using Na peroxide or Li borate fluxes may be required to completely digest the sample in cases where a multi-acid attack may
only liberate the LREE(Fig. 5).
4 Acid/MS OREAS 100a
Fusion/MS OREAS 100a
4 Acid/MS OREAS 101a
Fusion/MS OREAS 101a
4 Acid/MS OREAS 102a
FusionMS OREAS 102a
4 Acid/MS OREAS 146
Fusion/MS OREAS 146
Fig.5. Recovery of REE from Uranium and REE ores
with four acid and sodium peroxide fusion.
Techniques for Rare Earths Exploration
The refractory nature of many of the minerals which host rare earth elements (REE) make fusion followed by a combination of ICP-OES and ICPMS an ideal technique for the accurate characterisation of REE ores along with important major, minor and trace components. Fusions, using
either sodium peroxide or lithium borate flux, ensure the complete digestion of all minerals giving total elemental analyses. All data are checked
for consistency using chondrite normalised plots.
An extended REE package including the major elements is available on request, as well as a wider selection of elements including Cs, Rb, Ba, Sr,
V and Sc. Low level lithogeochemistry options are also available, including the combined digest, where a four acid digest is followed by fusion for
total heavy rare earths recovery and low detection limits.
If you are exploring in areas of cover, regolith sampling with partial selective digests or vegetation sampling may work in the area of interest.
Anyone is most welcome to contact the laboratory for further information.
Rare earths mineralisation,
© Clint Cox, The Anchor House, Inc. 2009
Bastnäsite ore, Mt Pass
© Clint Cox, The Anchor House,
Red Eudialyte with black Aenigmatite,
white feldspar and Aegirine
© Maurice de Graff, Takhtarvumchorr,
Khibiny massif, Russia, 2009.
Rare Earths Mineralisation Na Peroxide Fusion ICP-MS Package
Sodium peroxide is a highly effective, oxidising flux which melts at 495°C. It can be used to decompose a diverse array of rocks and ores to
determine many elements commonly hosted in refractory minerals, oxides, sulphides, silicates and carbonates. These include galena, sphalerite,
pyrite, molybdenite, arsenite, cassiterite, baddeleyite, ilmenite, wolframite, beryl, tourmaline, bismuth ores, manganese and iron ores, chromium
ores, niobium and tantalum ores, monazite, euxenite, xenotime, loparite, samarskite, bastnäsite. Rare earths minerals from peralkaline granitic
rocks are usually hosted in relatively refractory minerals like eudialyte, fergusonite, allanite, gittinsite and can be fully recovered with fusion.
REE Package by Na peroxide fusion Ni crucible / ICP-MS
Lu 5- 4%
10% 0.1- 10%
10% 0.1- 10%
10- 60% Y
0.1- 40% Yb
20- 70% Zr
0.5- 10% B
0.5- 20% Fe
0.1- 20% Mg
20- 50% S
REE Sodium peroxide fusion Ni crucible for metallurgical samples / ICP-MS
*not complete recovery
Rare Earths Mineralisation Li borate Fusion ICP-MS Package
Lithium borate fusion can be used when elements such as Na and K also need to be determined. The flux is an eutectic mixture of lithium
metaborate and lithium tetraborate and is effective for a wide variety of oxide, silicate and carbonate minerals26.The fusion is done at higher
temperature (1000°C) and potentially leads to the losses of volatiles. This method uses platinum for the crucibles and is not recommended for
samples with high sulphide sulphur or copper contents.
0.02 - 2%Be
REE Package by Li borate fusion / ICP-MS
Rare Earths Combined Digest Package
The combined digest offers a combination of low detection limits and complete dissolution by fusion the residue of four acid digest with lithium
borate and recombining this with the acid digest solution. This package is useful for the lithogeochemical characterisation of ultramafic rocks,
where REE and tantalum, in particular, are present in very low concentrations which maybe close to or below the detection limit of the lithium
borate fusion method alone.
Combined digest / ICP-MS
High Field Strength Element (HFSE) Combined Digest
Range ppm Hf
Range ppm Element
Combined digest / ICP-MS
Powder XRD is used in many areas where the identification of unknown materials is required; these include geological, environmental,
material science, biological and industrial applications.
The results given are either qualitative (descriptive of the sample make-up) or quantitative. Quantitative results can include the non-crystalline
XRD Pulverise Package
Crush -2mm, rotary split 800g, pulverise 800g to 60um
Qualitative analysis for complete mineralogy
Quantitative analysis for complete mineralogy (crystalline content only)
QUANTITATIVE Quantitative analysis for complete mineralogy and amorphous content
QUANTITATIVE Quantitative analysis for complete mineralogy and amorphous content
(2 x Scan analysis)
Rare earths-Uranium deposit classification27,28
Deposit Type Example
Surface Processes /
U, Au, Ag
uranothorite, brannerite, coffinite,
pyrophyllite, chloritoid, muscovite,
chlorite, quartz, rutile, and pyrite
Santa Quiteria and Itataia P-REE-Nb±Sr-Ca-Al-K-Umines, Florida and Idaho, Ti-Ta
fluorite, apatite, phosphorite,
Serres Basin, North and
South Dakota, Mulga
clay-rich lignit, carbonaceous sands
and clays (kaolinite), coffinite,
brannerite, ilmenite, rutile, anatase
Rudnoye and ZapadnoKokpatasskaya deposits
The Wyoming basins,
Inkai, Niger, Gabon,
U±S-As-Se-Mo-Co-Ni-VCu-Zn-Pb-REE-Y (Si-OC-P), Sc, Au, Ag
marine organic-rich shale or coalrich pyritic shale, containing synsedimentary disseminated uranium
adsorbed onto organic material
U, Se, Mo, V, Cu, Pb
Heavy mineral Coburne, Murray Basin,
sand deposits Cooljarloo
zircon, ilmenite, rutile, leucoxene,
Unconformity- Alligator River,
Coronation Hill, The
U-Au-Cu-Co-Ni-Ag±ZnSn-Pb-Bi, Pt-Pd (Mg)
U, Mo, Pb, F
uranit, coffinit, brannerite, in shear
zone (brannerite, thorite)
Olympic Dam, Ernest
uranit, coffinite, (meta)-torbernite,
U, Pb, W, Sn
U, Th, REE
uraninite, brannerite, thorite,
allanite, coffinite, uranophane
U, REE, Zr, Nb, Be, Sr
agpaiticnepheline, syenite, alaskite,
Sn-Ta-Nb-Li, Be-Li-CsRb±U-Th REE (Si)
uranit, garnet, columbite, tantalite,
niobite, spodumene, lepidolite,
tourmaline, cassiterite, holtite,
uraninite, pitchblende, which occur
as cavity fills and coatings on quartz
Rare earth minerals that occur in economic or potentially economic deposits
Found in close association with calcite and barite in barite veins that
cut a dolomitic metamorphosed limestone. Epidote group.
Usually secondary, derived from other Ti-bearing minerals. Common
as a detrital mineral
In hydrothermal veins in nephelinesyenites.
Contact or alteration zones in alkalic rocks.
Found in the same settings as gold, including placers, quartz veins,
and in granite pegmatities. Alteration product of uraninite.
In nephelinesyenites, pegmatites and contact deposits related to
Partially absorbed inclusions of wall-rock in a dikelike zone of carbon- 81
ate rock cutting nephelinesyenite.
Disseminated in a kaolinitized pegmatite dike. Cheralite-(Ce) (1953) is 5
now regarded as Ca-rich monazite-(Ce).
Scarce rare earth mineral associated with phosphate minerals.
granitepegmatites and a component of detrital black sands.
Rare earth deposit.
Found in placer sands
In syenite pegmatite veins along a contact between basalt and monzonite.
Hydrothermal veins associated with rare-earth-bearing carbonatite
deposits in alkaline igneous complexes.
Red karstic bauxites.
In vugs in pegmatites in granites and alkalic complexes.
Primary mineral in differentiated nephelinesyenite massifs and alkalicpegmatites, replacing perovskite in carbonatites.
Alteration product of rinkite.
In calcite veins in hydrothermal deposits.
Accessory mineral in REE-rich granite pegmatites.
Found with parisite in REE-bearing pegmatites and alpine veins.
Minor accessory mineral in both acidic and alkalic igneous rocks and
Accessory mineral in granite pegmatites.
*The formular is for specific chemical variant of the mineral identified. Note one or more other chemical variants, in which the dominant element
varies from the one shown, may exist.
Production advanced deposits/
other than alkaline
Rock Canyon Creek
Nechalacho (Thor Lake)
Green Cove Springs
Barro do Itapirapua
Lovoze ro complex
Nile Delta and Rosetta
Kute ssay ll
69 Mount Weld
70 Cummins Range
72 Nolans Bore
73 Olympic Dam
74 Mary Kathleen
75 WIM 150
76 Dubbo Zirconia
77 Fraser Island
78 North Stradbroke Island
Figure 6. Map showing the global distribution of REE deposits9
U.S. Geological Survey, Mineral Commodity Summaries, 2009.
REE handbook, PROEDGE wire, http://www.reehandbook.com
U.S. Geological Survey, Mineral Commodity Summaries, 2010.
U.S Geological Survey, Mineral Commodity Summaries, 2011
Zaichenget al.2012.Monodisperse Fluorescent Organic/Inorganic
Composite Nanoparticles, 24 (17), 3415-3419.
6 TG Daily. New fluorescent OLEDs more efficient than once believed.by
David Gomez. http://www.tgdaily.com/
7 Campbell et al. 2010, Rare earth colorants: Ceramics Today, January 26.
8 Yoldjian et al. 1985, The use of rare earths in ceramics: Journal of the
Less Common Metals, v. 111, no. 1–2, September.
9 British Geological Survey, 2011.
10 Kennedy, 2010.Critical Strategic Failure in Rare Earth Resources – A
National Defense and Industrial Policy Failure.Society of Mining,
Metallurgy and Exploration Meeting.
11 Attrep, Moses, Jr.; and P. K. Kuroda, 1968, Promethium in pitchblende:
Journal of Inorganic and Nuclear Chemistry v. 30, no. 3, p. 699-703
13 http://www.reuters.com, March 2011
14 Industrial Minerals, 19 Nov, 2012; http://www.vinacomin.vn
21 Rudnick, L.R. 1991. Restites, Eu anomalies, and the lower continental
crust. GeochemicaetCosmochimica, 56, 963-970.
22 Shields, G. et al. 1998. Stratigraphic trends in cerium anomaly in
authigenic marine carbonates and phosphates: diagenetic alteration or
seawater signals. Goldschmidt conference Toulouse.
23 Graf, J.L. 1977. Rare earth elements as hydrothermal tracers during
the formation of massive sulphide deposits in volcanic rocks, Economic
Geology, v.72, no. 4, p. 527-548.
24 Schade, J., Cornell, D.H., Theart, H.F.J. 1989. Rare earth element and
isotopic evidence for the genesis of the massive sulfide deposit, South
Africa. Economic Geology 84, 49-63.
25 Castor, S.B. et al. Rare earth elements, Fieldex Exploration. http://www.
26 Thomas R. Dulski. 1996. A manual for the chemical analysis of metals.
27 McQueen, K.G. Ore deposit types and their primary expressions. CRC
28 Lally, J. et al. 2006, Report 20: Uranium Deposits of the NT., Northern
Territory Geological Survey.
29 Source for mineral formulas: Webmineral.com
Perth Contact Details
Richard Holdsworth QA/QC Chemist 15 Davison Street, Maddington Western Australia Ph: +61 8 9251 8100 Evgenia Lebedeva
15 Davison Street, Maddington
Ph: +61 8 9251 8100