Rare Earth Element Deposits

Rare Earth Element Deposits

The REE and the Periodic Table

Li ³ H ¹

Na K Rb Cs Fr

Be Mg Ca Sr Ba Ra

Sc Y La Ac

Ti Zr Hf Rf

V Nb Ta Db

Cr Mo W Sg

Mn Tc

Re Bh

Fe Ru Os

Co Rh Ir

Ni Pd Pt

Ag Au

Cd Hg

B Al Ga In Tl

C Si Ge Sn Pb

N P As Sb Bi

O S Se Te Po

F Cl Br I At

He Ne Ar Kr Xe Rn

11 19 37 55 87

4 12 20 38 56 88

21 22 23 24 25 26 27 28

Cu Zn^{29 30 31 32}

39 40 ^{41 42 43 44 45 46 47 48 49 50 51 52 53 54}

36 18 10 2

5 6 7 8 9

17 15 16

14 13

33 34 35

57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

89 104 105 106 107

Hs Mt Ds^{108 109 110 111}Uuu Uub Uuq^{112 114}

Ce⁵⁸ Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu^{59 60 61 62 63 64 65 66 67 68 69 70 71}

Light REE Heavy REE

Wilhelm Hisinger

“Ceria” “Yttria”

Johan Gadolin

The Discovery of the REE

Bastnäs

LR EE

Ytterby

HR EE 178 8 17 81

1766 - 1852

1760 - 1852

Gadolin Discovers “Yttria”

{Y₂FeBe₂Si₂O₁₀ }

Gadolinite

Gadolin dissolves a black rock in a HNO₃/ HCl mixture leaving behind silica. He precipitated Be, Fe, with a solution of K₂CO₃ as Be(OH)₂ and FeCO₃. The remaining solution, when mixed with NH₃, precipitated a yellow solid which he named “yttria”.

Gadolin (1794)

1 cm

Gadolinite The abandonded Ytterby

feldspar mine, Sweden

Hisinger/Berzelius dissolve Bastnäs

“tungsten” in HNO₃, neutralise the solution in KOH, add potassium

tartrate and precipitate a yellow solid.

They name it “ceria” after the dwarf planet Ceres.

Wilhelm Hisinger Jöns Berzelius

The Discovery of “Ceria”

1 cm

Cerite

Allanite Cerite

Cerite

{Ce₉FeSi₇O₂₇(OH)₄}

Hisinger and Berzelius (1804)

Hisinger’s red

“tungsten” at

Bastnäs, Sweden 1779 - 1848

1776 - 1852

Mosander Starts Separating the REE by fractional precipitation

Carl Mosander (1797 – 1858)

“nitric acid diluted with 75 to 100 parts of

water...leaves the

greater part of the red- brown oxide (‘ceria’) undissolved, and from the solution thus

obtained, the oxide of lanthanium was derived”

(Mosander, 1839)

By 1843, Mosander had separated lanthanum and cerium from “ceria” and erbium, terbium and yttrium from “yttria”

A Use for the REE

In 1885 Auer von Welsbach invents an incandescent mantle, dipping

guncotton in a REE-solution - he had discovered REE-phosphorescence - soon his mantles were lighting up the homes, factories and streets of

Europe. He also invented lighter flints – 70% mischmetal, 30% iron

Modern Uses of the REE

The REE and Wind Power

Wind power now supplies 11.4% of the European Union’s electricity (141.6 GW; growing at 15.6% /yr).

Wind turbines are driven by

(Nd,Dy)₂Fe₁₄B magnets requiring 730 Kg of Nd and Dy per MW.

In the U.S., wind power supplies 4.4% of electrical energy (74.5 GW); also growing at 15.6%/yr.

In 2015, China overtook the EU with 145.1 GW of installed wind turbine power capacity, a 27% 1 yr growth (supplies ~4% of electrical energy)

The REE and Hybrid Cars

Each hybrid / electric car

consumes ~28 Kg of REE mainly in magnets and La-Ni-hydride batteries

During 2013 hybrid car sales in the US totalled 500,000 units up 14% from 2012 , representing 3%

of new car sales.

The Strategic Importance of the REE

US Production Chinese Production

Not all REE are Equally Critical

Medium term criticality matrix (2015 -2025)

U.S. Department of Energy (2011)

Rare Earth Element Deposits

Nechalacho

Strange Lake

Bayan Obo Maoniuping Lovozero

Mt Weld Mountain

Pass

Lofdal Bear Lodge Kipawa

Carbonatite

Nepheline syenite Granite

Hydrothermal

Ion adsorption clay

Mine Prospect

Ilímaussaq

Relative Abundance of the REE in the Earth’s Crust Normalized to Primitive

Mantle

Y

LREE

HREE

HREE

U nd er st an di ng

Time

RE E De po sit s

Porphyry/epithermal

REE Ore Genesis – the Current State of Understanding

Effective mineral exploration requires robust models of ore genesis

The Hosts to REE Deposits

Alkaline igneous rocks and carbonatites

Carbonatites; LREE deposits, main ore minerals, monazite-(Ce), basnäsite-(Ce)

Nepheline syenites;

HREE deposits,

A-type granite pegmatites; HREE deposits, ore minerals, secondary gadolinite-(y), bastnäsite-(Ce)

main primary ore mineral, eudialyte; secondary

fergusonite-(Y)

Ce

Eu

REE

Io ni c ra di us ( A ng st ro m s)

Y

Heavy

Light

The Lanthanide Contraction

Incompatible elements are concentrated by low degrees of partial melting

Light and Heavy REE deposits

Carbonatite-hosted

deposits are invariably light REE-rich.

Nepheline-syenite- and A- type granite-hosted REE deposits are relatively

enriched in the heavy REE.

Carbonatites are the

products of either very low degrees of partial melting or liquid immiscibility, both of which favour the most incompatible elements, the LREE.

Chakhmouradian & Zaitsev. (2012)

Post-Archean Australian Shale

REE Concentration in mg/Kg REE Concentration normalised to chondrite

The Effect of Normalisation

The normalisation to chondrite smoothes the saw-toothed pattern and makes it possible to

observe that relative to chondrite, shales are

enriched in the LREE and display a marked

negative Eu anomaly.

Oceanic Alkaline Magmatism

Continental Alkaline Magmatism

Depleted Upper Mantle

Undepleted Lower Mantle

The Source of Alkaline Magmas

The Role of Mantle Metasomatism

Dehydration /melting of subducting slab/sediments transfers H₂O,

CO₂, F, Cl, HFSE/REEs to

subcontinental lithospheric mantle and asthenospheric mantle.

Volatile-rich carbonatites and kimberlites stall, crystallize and

release volatiles and F/Cl-complexed HFSE/REEs into subcontinental

lithospheric mantle and crust

Environments of Alkaline Magmatism

Back Arc Intraplate

Continental Swell Continental Rift

Mountain Pass Strange Lake

Maoniuping Lovozero

Nechalacho

Carbonatite-hosted REE Deposits

Magma evolution

Calcio-carbonatite magnesio-carbonatite ferrocarbonatite

CaO

MgO FeO + MnO

Ferrocarbonatite Calcio-carbonatite

Ferruginous carbonatite

Magnesio-carbonatite

The REE mineralisation is progressively enriched from magnesio-

carbonatite to ferrocarbonatite

The example of the Eldor carbonatite, Québec; bulk-rock compositional data.

Rim BD Zone A-Zone

MHREO-Zone B-Zone

REE

Beland & Williams-Jones. (in prep)

Carbonatite-hosted REE Mineralisation

Dolomite 1 (primary); Dolomite 2 (hydrothermally altered

Dolomite 1); and Dolomite 3 (hydrothermal dolomite filling vugs with bastnäsite-(Ce) and parisite-(Ce)

XFe = 0.41 XFe = 0.30

XFe = 0.24

The example of the Wicheeda LREE carbonatite Deposit, British Columbia (11.3 Million tons grading 1.95 wt% REE)

In most carbonatite-hosted deposits, the REE mineralisation is hydrothermal.

Trofanenko et al. (2016)

Carbonatite-hosted REE Mineralisation

At Wicheeda, the calcio-carbonatite has a mantle isotopic signature, the dolomitic carbonatite an igneous signature and the vug-filling dolomite accompaning bastnäsite-(Ce), a hydrothermal signature.

A model is proposed in which the REE

mineralisation was the product of late

magmatic carbo-

hydrothermal fluids at ~ 300 C.

Trofanenko et al. (2016)

Strange Lake Nechalacho

Silica-saturated magma

Silica-undersaturated magma

Mafic magma

Mantle

Felsic magma

Crust

Rifts, Plumes and REE-Rich Magmas

Peralkaline granite (A-type) Layered nepheline syenite complex

The Nechalacho (Thor Lake)

REE Deposit

100 m

Long Lake

Basal Zone Upper Zone

Sodalite S

yenite Sodalite Foyaite

Micro-layered Agirine Nepheline Syenite Thor Lake

Syenite Grace Lake Granite

Cross-Section through part of the Nechalacho Layered Suite

Nepheline syenite

The Ore Zones

Upper ore zone

Basal ore zone Albitite

Unaltered aegirine nepheline syenite

Zrn Bt

Bt, Mt _{0.5 cm}

0.5 cm

Eud

Bt, Mt

Na₁₅(Ca, REE)₆(Fe,Mn)₃Zr₃NbSi₂₅O₇₂(O,OH,H₂O)₃

Eudialyte Sodalite

syenite

Basal Zone REE Mineralisation

Pseudomorphs after eudialyte

0.5 cm

Bt, Mt, Hm

Pseudomorph after eudialyte in plane polarised light

Qtz

Mt

Zrn Mnz Bt Cal

0.1 cm Fer

Magmatic concentration of the REE in Nechalacho Layered Complexes

Sodalite

Zr Silicate

Aegirine Nepheline

Crystallisation from roof down and floor up

Residual, volatile (F, Cl)- and

HFSE-rich magma saturates with

REE-bearing zirconosilicates (zircon, eudialyte)

The REE “stew in these juices” and are mobilised

Yttrium

20µm

Yttrium

100µm

Yttrium

40µm

Zircon Fergusonite

Progressive alteration of zircon

100µm Zirconium

100µm Yttrium

Alteration of eudialyte to zircon and REE minerals

Hydrothermally Unlocking the REE

LREE mobilised upwards and deposited as Bastnäsite-(Ce) and monazite –(Ce)

Sheard et al. (2012)

HREE deposited locally, mainly as fergusonite-(Y) {Y,NbO₄}

Strange Lake Nechalacho

Silica-saturated magma

Silica-undersaturated magma

Mafic magma

Mantle

Felsic magma

Crust

Rifts, Plumes and REE-Rich Magmas

Peralkaline granite (A-type) Layered nepheline syenite complex

The Strange Lake HREE Deposit

www.questrareminerals.com

REE Reserves

The Strange Lake Granitic Pluton

1 km

Subsolvus granite

Hypersolvus granite

B-Zone M-Zone

Hypersolvus granite

Pegmatite border Pegmatite core

The Strange Lake Pegmatite Ores

REE Minerals Titanite

(CaTiSiO₅) Gittinsite

(CaZrSi₂O₇) Fluorite

Nb Ce Eu Dy Y Be

Zr

F

Porou s Porou

s

15

20

25

30

P eg m at ite

Distribution of REE and Zr in Pegmatite

Magmatic Concentration of REE/HFSE by Segregation of a late Volatile-rich Melt

Primary magma containing high concentrations of

REE/HFSE (crystallised) Residual liquid enriched in

incompatible REE/HFSE and volatiles

Crystals

Evolved magma further enriched in REE/HFSE

Further evolved liquid highly enriched in incompatible

REE/HFSE and volatiles

REE/HFSE Pegmatites

Crystals

Melt Inclusions in the Hypersolvus Granite

Melt Inclusions are evident by their

spherical shape. They vary from being

silicate-only, to fluorite- bearing to fluoride-

only.

Vasyukova and Williams-Jones (2014)

Fluorite-bearing Melt Inclusions after Heating and Quenching

Transmitted Light SEM Image

1 –Silicate melt enriched in Zr

2 –Ca-fluoride melt;

10 wt.% REE

3 –REE-fluoride

melt; 50 wt.% REE

Acidic Alteration and REE Mobilisation

Autometasomatism lead to acidic

alteration by HCl-HF- bearing fluids that destroyed the

primary mineralogy, creating porosity

REE mobilised, replacing earlier minerals and filling vugs

Flc - fluocerite (REEF₃)

Gysi and Williams-Jones (2013)

The Pegmatites Stewed in their own Juices

Gysi and Williams-Jones (2013)

Mobilisation of the REE

Gysi et al. (2016)

The LREE were mobilised preferentially leaving the HREE concentrated

closer to the pegmatites (LREE are more mobile than HREE, discussed later)

Model of REE Accumulation

Fractional crystallization

Fractional crystallization

Cooling Cooling

Subsolvus granite Subsolvus

granite PegmatitePegmatite

Hydrothermal fluid

MobilisREE ed

F

Poro us Poro

us

Zr Y

Hydrothermal REE Deposits

Monazite (LREEPO₄) and bastnäsite (LREECO₃F), together with magnetite,

hematite and fluorite replaced H8 dolomite . Fluids 5 – 15 wt% NaCl eq., T > 400 C.

Smith & Henderson (2000)

The Bayan Obo deposit, China, is thought by some to be carbonatite-hosted and others to be hosted by dolomitic marble that was replaced by

magnetite, hematite, REE minerals, aegirine, and fluorite.

Bayan Obo replacement ore.

Pearson’s HSAB Principles and Aqueous Metal Complexes

Hard acids (large Z/r) bond with hard bases (ionic bonding) and soft acids (small Z/r) with soft bases (covalent bonding).

Hard Borderline Soft

Acids

Fe²⁺,Mn²⁺,Cu²⁺

Zn²⁺>Pb²⁺,Sn²⁺, As³⁺>Sb³⁺=Bi³⁺

H⁺, Na⁺>K⁺ Al³⁺>Ga³⁺

Y³⁺,REE³⁺ (Lu>La) Mo⁺⁶, W⁺⁶, U⁺⁶

Zr⁴⁺,Nb⁵⁺

Bases

F^-,OH^-,CO₃^2- >HCO₃^- SO₄^2- >HSO₄^-

PO₄^3-

Cl-

Au⁺>Ag⁺>Cu⁺ Hg²⁺>Cd²⁺

Pt²⁺>Pd²⁺

HS^->H₂S CN^-,I^->Br^-

Pearson (1963)

Log K REEF

Log K REECl

Solid lines – experimental data of Migdisov et al. (2009)

Dashed lines – theoretical

predictions of Haas et al. (1995)

The Stability of REE-F & -Cl Complexes

Stability of REEF²⁺ complexes high, decreases with increasing atomic number.

Stability of REECl²⁺ complexes, moderate, decreases with

increasing atomic number.

Migdisov et al. (2009))

Williams-Jones et al. (2012)

The Effect of Temperature on Fluocerite-

(Nd) (NdF

) Solubility

Modelling REE Mineral Solubility in a F- Bearing Brine

10 wt.% NaCl, 500 ppm F, 200 ppm Nd

The REE are transported dominantly as chloride complexes despite the greater stability of REE fluoride complexes, because HF is a weak acid and REE fluoride is relatively insoluble. Migdisov and Williams-Jones (2014)

Hydrothermal Fractionation of the REE

LREE are mobilised (as chloride complexes) relative to the HREE;

the REE are deposited as monazite.

Fluid contains 10 wt.

%NaCl, 500 ppm F, and 50 ppm of each REE. Rock contains 100 ppm P

Williams-Jones et al. (2012)

Lofdal, Namibia a Remarkably HREE-rich REE Resource

The deposit is described in the literature as carbonatite-hosted (Wall et al., 2008). We disagree!

The Lofdal HREE Deposit, Namibia

The Lofdal HREE deposit is associated with 750 Ma nepheline syenites and calcio-carbonatites that were emplaced during intracontinental rifting which

preceded amalgamation of Gondwana.

REE-Mineralised Structures

The REE-mineralised structures give the appearance of ferrocarbonatite dykes but are instead fault-controlled sodic fenites (albitites) that have been altered to calcite and/or ankerite. The red colour reflects pyrite oxidation.

Lithogeochemical Survey

The potential ore deposit with zones of strong fenitisation/carbonate alteration (dark grey) and weaker fenitisation (light grey). The coloured dots show the distribution of Dy in surface rock samples. Xenotime-(Y) concentrates in the structure and bastnäsite-(Ce) distally from it.

>700 300-700 100-300

<100

Dy ppm

Xenotime Bastnäsite

Bastnäsite

106 ppm Ce 2987ppm Y 1124ppm Th

REE Mineralisation in Core

Albitite clast containing xenotime-(Y) in a dolomite-cemented breccia Ce 152ppm

Y 1470ppm

Albitite containing HREE-enriched, biotite-filled shears

Dolomite Albite

Xenotime-(Y) Mineralisation

Albitite cut by xenotime-(Y)-zircon-biotite veins and then replaced by calcite.

Calcite

Rutile

Calcite Rutile

Albite Xenotime

and zircon

100 µm Calcite

Calcite Albite

Hydrothermal REE Fractionation

Ion Adsorption Clay Deposits

The REE are leached by humic acids and transported down the soil profile into the B-zone where they are concentrated by adsorption as the REE³⁺ onto the surfaces of clay minerals, mainly kaolinite. Many of the deposits are

HREE-rich with grades between 0.2 and 0.35 wt.% REE₂O₃

A

B

C

Solution Mining For HREE, China

1) Ammonium sulphate is dripped into weathered granite hill-tops, 2) ion adsorbed REE leached, 3)

solutions collected down slope and channeled into holding tanks,

4)REE precipitated with oxalic acid.

Recovery of the REE

(NH₄)₂SO₄ + REE³⁺ = REESO₄⁺ + 2(NH₄)⁺

The REE are dissolved to form REE sulphate complexes according to the ion exchange reaction (NH₄⁺ displaces the REE³⁺ on the clay mineral

surface):

and precipitate in the holding tanks as a result of the addition of oxalic acid.

2REESO₄⁺ + 3H₂C₂O₄ = REE₂(C₂O₄)₃ + 6H⁺ + 2SO₄^2-

The REE oxalate precipitates settle to the bottom of the

tanks and after draining of the fluid, they are removed, dried and bagged for transport to a refinery.

The resulting concentrate contains 60 – 90 wt% REE.

References

Gysi, A., & Williams-Jones, A.E. (2013). Hydrothermal mobilization of pegmatite-hosted REE and Zr at Strange Lake: a reaction path model.

Geochim. Cosmochim. Acta 122, 324-352.

Sheard, E.R., Williams-Jones, A.E., Heiligmann, M., Pederson, C., & Trueman, D.L. (2012). Controls on the concentration of zirconium, niobium, and the rare earth elements in the Thor Lake rare metal deposit, Northwest Territories, Canada. Econ. Geol. 107, 81-104.

Williams-Jones, A.E., Migdisov, A.A., & Samson, I.M. (2012). Hydrothermal mobilization of the rare earth elements – a tale of ‘ceria’ and ‘yttria’.

Elements 8, 355-360.

Vasyukova, O & Williams-Jones, A.E., (2014). Fluoride-silicate melt

immiscibility and its role in REE ore formation: Evidence from the Strange Lake rare metal deposit, Quebec-Labrador, Canada. Geochimica et

Cosmochimica Acta, 139, 110-130.

Chakhmouradian A.R. & Zaitsev, A.N. (2012). Rare Earth Mineralization in igneous rocks.: Sources and Processes. Elements 8, 355-360.

Migdisov, A. A. & Williams-Jones, A.E., (2014). Hydrothermal transport and deposition of the rare earth elements by fluorine-bearing aqueous fluids.

Mineralium Deposita, 49, 987-997.

References (continued)

Trofanenko, J., Williams-Jones, A.E., Simandl, G.J., & Migdisov, A.A. (2016).

The nature and origin of the REE mineralization in the Wicheeda carbonatite, British Columbia, Canada. Economic Geology, 111, 199-223.

Smith, M.P., & Henderson, P. (2000). Peliminary fluid inclusion constraints on fluid evolution in the Bayan Obo Fe-REE-Nb deposit, Inner Mongolia, China. Economic Geology, 95, 1371-1388.

Chakhmouradian, A.R. & Zaitsev, A.N. (2012). Rare earth mineralization in igneous rocks: Sources and Processes. Elements, 8, 347-353.