Rare Earth Element Deposits

The REE and the Periodic Table

Li3

H1

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 28Cu 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

1716151413

33 34 35

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

89 104 105 106 107Hs Mt Ds Uuu Uub Uuq108 109 110 111 112 114

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu58 59 60 61 62 63 64 65 66 67 68 69 70 71

Light REE Heavy REE

Ytterby and Bastnäs

Wilhelm Hisinger

Johann Gadolin

LREE

Ytterby

Bastnäs

HREE

1787

1751

“Yttria”

“Ceria”

The Discovery of the REE

{Y2FeBe2Si2O10 }

Ceria and Yttria

GadoliniteCerite {Ce9(Fe,Mg)Si7O27(OH)4}

1 cm

Cerite

Allanite

Cerite

Bastnäs (Skarn) Ytterby (Pegmatite)

Tungsten – heavy stone

1 cm

Gadolinite

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

Uses of the REE

China

USAOther

Global Production of the REE

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

Y

LREE

HREE

HREE

Major REE Deposits around the World

Bayan OboMountain

Thor LakeLovozero

IlimaussaqStrangeLake

Khibina

Maoniuping

Mount Weld

Pass

Lofdal

Nora Karr

Browns Ranges

Steenkampskraal

Und

erst

andi

ng

Time

REE Deposit

s

Porphyry/epithermal

REE Ore Genesis – the Current State of Understanding

Effective mineral exploration requires robust models of ore genesis

Strange Lake Thor Lake

Felsic magma

Silica-saturated magma

Silica-undersaturated magma

Crust

Mafic magmaMantle

Failed Rifts and REE-Rich Magmas

REE/HFSE, volatile- rich (H2O,CO2, Cl, F,) mantle

Low degrees of partial melting needed to produce peralkaline, F-REE-HFSE-rich magmas: carbonatites, nepheline syenites.

Metasomatised crust needed to produce REE/HFSE felsic melts

The Nechalacho (Thor Lake) REE Deposit

100 m

Long Lake

Basal Zone

Upper ZoneSodalite Syenite

Sodalite Foyaite

Micro-layered Agirine Nepheline Syenite

Thor Lake Syenite Grace Lake

Granite

Cross-Section through part of the Nechalacho Layered Suite

The Ore Zones

Upperore zone

Basalore zone

Albitite

Unaltered aegirine nepheline syenite

BtZrn

Bt, Mt0.5 cm

0.5 cm

Eud

Bt, Mt

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

Eudialyte

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

YttriumAlteration 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}

The Strange Lake HREE Deposit

www.questrareminerals.com

REE Reserves

The Strange Lake Granitic Pluton

1 km

Subsolvusgranite

Hypersolvusgranite

B-Zone M-Zone

Hypersolvusgranite

Pegmatite border Pegmatite core

The Strange Lake Pegmatite Ores

REE MineralsTitanite

(CaTiSiO5)Gittinsite

(CaZrSi2O7) Fluorite

Nb Ce Eu Dy YBeZr

F

Porous

Porous

15

20

25

30

Peg

mat

ite

Distribution of REE and Zr in Pegmatite

Gadolinite-groupFluorite

Gittinsite

TitaniteK-feldspar

Qtz

K-feldspar

Hydrothermal Mobilisation of HREE, Zr and Ti

(CaZrSi2O7)

(Ce,La,Nd,Y)2FeBe2Si2O10.

The Pegmatites Stewed in their own Juices

Gysi and Williams-Jones (2013)

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

Fractional crystallizatio

n

Fractional crystallizatio

n

coolingcooling

Subsolvus granite

Subsolvus granite PegmatitePegmatite

Hydrothermal fluidREE

Mobilised

F

Porous

Porous

Zr Y

Model of REE Accumulation

The Bayan Obo REE Deposit, China

Monazite (LREEPO4) and bastnäsite (LREECO3F), together with magnetite, hematite and fluorite replaced H8 dolomite . Fluids 5 – 15 wt% NaCl eq., T > 400 C.

Smith and Henderson (2000)

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-,CO32- >HCO3

-

SO42- >HSO4

-

PO43-

Cl-

Au+>Ag+>Cu+ Hg2+>Cd2+

Pt2+>Pd2+

HS->H2SCN-,I->Br-

Pearson (1963)

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)

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.