Rare earth elements do not occur as free metals in the earth's crust, such that all naturally occurring minerals consist of mixtures of various REE and nonmetals. Bastnaesite, monazite and xenotime are the three most economically significant minerals of the more than 200 minerals known to contain essential or significant REE. The mineral bastnaesite is named from the Swedish village of Bastnäs, where cerium ore was mined in the late 1800's, which lies close to Tasman Metals Ltd's exploration project areas.
Bastnaesite and monazite are principal sources of the light REE's which account for about 95% of the REE currently utilised. Monazite is also the principal ore of thorium, containing up to 30% Th, which together with smaller quantities of U imparts radioactive properties. Xenotime and minerals such as allanite are common sources of the heavy REE and yttrium.
Bastnaesite occurs predominantly in calc-silicate rich rocks related to alkaline intrusive igneous complexes, in particular carbonatite. Monazite and xenotime are more common as accessory minerals in low-Ca granitoid rocks and pegmatites. Following weathering of these rock types, monazite and xenotime are concentrated in heavy mineral placer deposits because of their resistance to chemical attack and high specific gravity.
Other commercial sources of REE are apatite and loparite (western Russia), REE-bearing clays ("Longnan clay" or "southern ionic clay", Jiangxi Province, China), and various minerals such as allanite that are produced as a by-product of uranium mining (Canada). Of lesser importance are zircon (Th, Y and Ce) and euxenite. The main commercial source of scandium is as a by-product from the processing of uranium and tungsten.
A list of common rare earth element bearing minerals is provided below. "REE" is used to signify the chemical location where any of the rare earth elements may substitute.
| Mineral |
Mineral Chemistry |
wt % |
Discovery |
| Aeschynite |
(REE,Ca,Fe,Th)(Ti,Nb)2(O,OH)6 |
36 |
|
| Allanite (orthite) |
(Ca,REE)2(Al,Fe)3(SiO4)3(OH) |
30 |
1808: East Greenland |
| Anatase |
TiO2 |
3 |
1801: France |
| Ancylite |
SrREE(CO3)2(OH)•H2O |
46 |
1899: Greenland |
| Apatite |
Ca5(PO4)3(F,Cl,OH) |
19 |
Apatiti, Russia |
| Bastnasite |
REECO3F |
76 |
1838: Bastnas mine, Sweden |
| Brannerite |
(U,Ca,REE)(Ti,Fe)2O6 |
6 |
1920: Kelly Gulch, Idaho, USA |
| Britholite |
(REE,Ca)5(SiO4,PO4)3(OH,F) |
62 |
1901 |
| Cerite |
Ce9(Ca)Fe3+,Mg)(SiO4)6[SiO3(OH)](OH)3 |
60 |
1838: Bastnas mine, Sweden |
| Cerianite |
(Ce,Th)O2 |
81 |
1955 |
| Cheralite |
(REE,Ca,Th)(P,Si)O4 |
5 |
|
| Churchite |
YPO4•2H2O |
44 |
|
| Eudialyte |
Na15Ca6(Fe,Mn)3Zr3(Si,Nb)Si25O73(OH,Cl,H2O)5 |
10 |
1819: Greenland |
| Euxenite |
(REE,Ca,U,Th)(Nb,Ta,Ti)2O6 |
<40 |
1840: Jolster, Norway |
| Fergusonite |
REE(Nb,Ti)O4 |
47 |
1806: Greenland |
| Florencite |
REEAl3(PO4)2(OH)6 |
32 |
Minas Geraes, Brazil |
| Gadolinite |
REEFeBe2Si2O10 |
52 |
1788: Ytterby mine, Sweden |
| Huanghoite |
BaREE(CO3)2F |
38 |
|
| Hydroxylbastnasite |
REECO3(OH,F) |
75 |
|
| Kainosite |
Ca2(Y,REE)2Si4O12CO3•H2O |
38 |
|
| Loparite |
(REE,Na,Ca)(Ti,Nb)O3 |
36 |
1925: Kola peninsula, Russia |
| Monazite |
(REE,Th)PO4 |
71 |
1823: Miask, Ural |
| Mosandrite |
(Ca,Na,REE)12(Ti,Zr)2Si7O31H6F4 |
<65 |
1841: Norway |
| Parisite |
CaREE2(CO3)3F2 |
64 |
|
| Samarskite |
(REE,U,Fe)3(Nb,Ta,Ti)5O16 |
12 |
|
| Synchisite |
CaREE(CO3)2F |
51 |
|
| Thalenite |
Y3Si3O10(OH) |
63 |
|
| Xenotime |
YPO4 |
61 |
1824: Ytterby mine, Sweden |
| Yttrotantalite |
(Y,U,Fe)(Ta,Nb)O4 |
<24 |
|
| Zircon |
ZrSiO4 |
<5 |
1783: Sri Lanka |
| |
|
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