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Rare
Earth Elements (REE) Gems
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Rare
Earth Element minerals (also referred to as "REE
minerals") are minerals that contain at least one
of the fifteen chemical elements in the periodic table
known as the lanthanides, as well as scandium (Sc) and yttrium
(Y). Scandium and yttrium are not lanthanides but are
considered to be rare earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties.
The lanthanide series of chemical elements comprises the fifteen metallic elements with atomic numbers from 57 (lanthanum) through 71 (lutetium). The
fifteen lanthanides are (in order of atomic number
starting from the lowest): 57 lanthanum (La), 58
cerium (Ce), 59
praseodymium (Pr), 60
neodymium (Nd),
61 promethium (Pm), 62
samarium (Sm), 63
europium (Eu), 64
gadolinium (Gd), 65
terbium (Tb), 66
dysprosium (Dy), 67
holmium (Ho), 68
erbium (Er), 69
thulium (Tm),
70 ytterbium (Yb) and 71
lutetium (Lu). Click
here for more detailed information on the lanthanides
near the bottom of this page.
The
term "rare earth element" is somewhat outdated
as these elements are not particularily rare nor are they
"earths". "Earths" is an obsolete mineralogical
term referring to "water-insoluble, strongly basic oxides of electropositive metals incapable of being smelted into metal" (using late 18th century technology). The REE
elements certainly are not rare. Cerium is the most
abundant lanthanide and is the 26th most abundant element in the Earth's crust,
about as abundant as copper and more so than tin. Neodymium is more abundant than gold. The
scarcest of the lanthanides, thulium, is more abundant
than arsenic or mercury and they are not considered
to be rare. The
"rare" in rare earth elements originally referred to them
typically being widely
dispersed in very small quantities throughout the Earth's
crust and very
difficult to obtain in their pure form. Because lanthanides
tend to congregate in the same minerals, the original
isolation and identification of the lanthanides was
very difficult and took well over a century of scientific
development and discovery. It took over 100 years for
all of the natrually occuring lanthanides to be discovered
and over 150 years before the last lanthanide, the synthetic
Promethium, would be "discovered".
The
lanthanides are named after the element lanthanum (La)
because
it is the first in the group because it has the lowest
atomic number, 57, of the group. The name
"lanthanide" was introduced by Swiss born
mineralogist Victor Moritz
Goldschmidt (1888-1947)
in 1925. Victor Goldschmidt, together with Russian mineralogist and geochemist
Vladimir Vernadsky
(1863-1945),
were considered to be the founders of modern geochemistry and crystal chemistry.
Goldschmidt was also the developer of the Goldschmidt Classification of elements.
The name lanthanum comes from the Greek
word λανθανω (lanthánein) meaning to lie hidden.
This description may refer to the discovery
of the element lanthanum as it was discovered "lying
hidden" within a cerium bearing mineral that had
previously been analysed. Many of the lanthanides
were later discovered "lying hidden" within
minerals that had previously been analysed.
The
discovery of the lanthanides began in 1787 with the
discovery of the mineral Ytterbite. Swedish chemist
Carl Axel Arrhenius (1757-1824) found a dark mineral that
he could not identify in a feldspar mine near Ytterby, on the island of Resarön,
Sweden.
Arrhenius named the black mineral Ytterbite after the
nearby town of Ytterby. Arrhenius sent a sample of Ytterbite
to Finish chemist Johan Gadolin (1760-1852)
at Uppsala University, Finland, where he began
a detailed analysis of it in 1794. He found it contained
silica, alumina, iron oxide and an unknown "earth". Gadolin’s results were confirmed in 1797 by Swedish chemist Anders Gustaf
Ekeberg (1767-1813). Ekeberg suggested the name yttria (later called yttrium) for the oxide of the new
earth metal. Gadolin is credited with the discovery of the element yttrium.
The mineral Ytterbite was renamed Gadolinite in 1800 by German
chemist Martin Heinrich Klaproth (1743-1817) in honor of Johan Gadolin. Klaproth
discovered uranium, zirconium and cerium.
Yttrium
was the first of the rare earth elements to be discovered
from Ytterbite. But the yttrium discovered by Gadolin
also contained several other rare earth metal oxides.
Over the next century, several of the remaining lanthanides
were extracted from Ytterbite (Gadolinite). The Swedish
chemist Carl Gustaf Mosander (1797-1858) was responsible
for discovering lanthanum, erbium and terbium. The mineral
Mosandrite was
named in his honor in 1841.
The remaining
lanthanide elements, ytterbium, thulium, holmium, dysprosium, lutetium
and promethium, were discovered separately over many
years. In 1907 lutetium was the last of the naturally
occuring lanthanides to be discovered. However, the existence of an element between neodymium (atomic
number 60) and samarium (atomic number
62) was predicted by Czech chemist Bohuslav Brauner (1855-1935) in 1902. This was confirmed by English
phyisicist Henry Moseley (1887-1915) in 1914.
Finally in 1945, after many attempts by many scientists, firm evidence that element 61 had been isolated was
produced by Charles D. Coryell, Lawrence E. Glendenin,
Jacob A. Marinsky, and Harold G. Richter
at the Oak Ridge National Laboratory,
Oak Ridge, Tennessee. They produced element 61 by fission of uranium and neutron bombardment of neodymium
in a graphite reactor. They named the new element Promethium after the Greek Titan Prometheus, who, according
to Greek mythology, stole fire from Mount
Olympus to give to mankind. The name was accepted in 1949 by the International Union of Pure and Applied Chemistry
(IUPAC). Promethium is considered a synthetic element
and does not occur naturally in the Earth's crust. Promethium
has been identified however, in the spectrum of the star HR465 in the
Andromeda Galaxy approximately 780 kiloparsecs (2.5 million light-years; 2.4×1019 km) from Earth.
Listed
below are gems containing at least one of the
REE elements and the REE elements contained in
each one.
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More
detailed information on the 15 lanthanides plus scandium
and yttrium. Scandium and yttrium are not lanthanides,
but are considered to be rare earth elements. They are
listed in order of their atomic numbers.
Scandium
(not
a lanthanide, but considered a rare earth
element) |
atomic number: |
21
|
atomic radius: |
216 pm (Van der Waals)
|
atomic symbol: |
Sc
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
44.955912
|
melting point: |
1541°C
|
electron configuration: |
[Ar]4s23d1
|
boiling point: |
2836°C
|
oxidation states: |
3
|
color: |
silvery white, yellowish tarnish
|
year
discovered: |
1879
|
discovered
by: |
Lars Fredrik Nilson (1840-1899)
|
Scandium was
named from the Latin word Scandia, meaning Scandinavia. |
Yttrium
(not
a lanthanide, but considered a rare earth
element) |
atomic number: |
39
|
atomic radius: |
219 pm (Van der Waals)
|
atomic symbol: |
Y
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
88.91
|
melting point: |
1522°C
|
electron configuration: |
[Kr]5s24d1
|
boiling point: |
3345°C
|
oxidation states: |
3
|
color: |
silvery white, yellowish tarnish
|
year
discovered: |
1794
|
discovered
by: |
Johan Gadolin (1760-1852)
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Yttrium was
named after Ytterby, a town in Sweden
near where the
mineral Ytterbite (also named after Ytterby) was discovered
in 1787 by Swedish chemist
Carl Axel Arrhenius (1757-1824). Ytterbite was later
renamed Gadolinite in honor of Johan Gadolin (1760-1852)
who discovered the element yttrium from a Ytterbite
sample. |
Lanthanum
|
atomic number: |
57 |
atomic radius: |
240 pm (Van der Waals) |
atomic symbol: |
La |
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
138.9 |
melting point: |
918 °C |
electron configuration: |
[Xe]6s25d1 |
boiling point: |
3464 °C |
oxidation states: |
3 |
color: |
silvery white
|
year
discovered: |
1839 |
discovered
by: |
Carl
Gustaf Mosander (1797-1858) |
Lanthanum
was named from the Greek word lanthanein
(λανθανω), meaning
to escape notice. |
Cerium
|
atomic number: |
58
|
atomic radius: |
235 pm (Van der Waals) |
atomic symbol: |
Ce
|
standard
state: |
solid
at |
atomic weight: |
140.1
|
melting point: |
798 °C |
electron configuration: |
[Xe]6s24f15d1
|
boiling point: |
3443 °C |
oxidation states: |
4,
3 |
color: |
silvery white
|
year
discovered: |
1801
|
discovered
by: |
Martin Heinrich Klaproth (1743-1817) |
Cerium was named after the asteroid Ceres, which was discovered on
January 1, 1801,
two years before the discovery of cerium.
Ceres was discovered and named by Italian astronomer Giuseppe Piazzi (1746-1826)
after Ceres, the Roman goddess of agriculture.
Ceres is the largest object in the asteroid belt which lies between the orbits of Mars and Jupiter.
It was originally considered a planet, but was reclassified as an
asteroid in the 1850s. It was designated as a dwarf planet by the International Astronomical Union (IAU)
in 2006.
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Praseodymium
|
atomic number: |
59
|
atomic radius: |
239 pm (Van der Waals)
|
atomic symbol: |
Pr
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
140.9
|
melting point: |
931°C
|
electron configuration: |
[Xe]6s24f3
|
boiling point: |
3520°C
|
oxidation states: |
3
|
color: |
silvery white, yellowish tinge
|
year
discovered: |
1885
|
discovered
by: |
Carl Auer von Welsbach (1858-1929)
|
Praseodumium
was named from the Greek words prasinos (πράσινος), meaning green, and didymos (δίδυμος),
meaning twin. Praseodymium and neodymium
are called "twins" because they
are so much like lanthanum.
Praseodymium is the "green" twin because when it becomes moist, it
reacts with
the oxygen
in air to form praseodymium oxide which forms as a greenish-yellow scale (like rust) on its surface. To protect it
from this reaction, it should be stored in
mineral oil. |
Neodymium
|
atomic number: |
60
|
atomic radius: |
229 pm (Van der Waals)
|
atomic symbol: |
Nd
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
144.242
|
melting point: |
1021°C
|
electron configuration: |
[Xe]6s24f4
|
boiling point: |
3074°C
|
oxidation states: |
3
|
color: |
silvery white, yellowish tinge
|
year
discovered: |
1885
|
discovered
by: |
Carl Auer von Welsbach (1858-1929)
|
Neodumium
was named from the Greek words neo
(νέος) meaning new, and didymos (δίδυμος),
meaning twin. Neodymium and praseodymium
are called "twins" because they
are so much like lanthanum. |
Promethium
|
atomic number: |
61
|
atomic radius: |
236 pm (Van der Waals)
|
atomic symbol: |
Pm
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
145
|
melting point: |
1042°C
|
electron configuration: |
[Xe]6s24f5
|
boiling point: |
~3000°C
|
oxidation states: |
3,
2 |
color: |
silvery white, yellowish tinge
|
year
discovered: |
1945
|
discovered
by: |
Charles D. Coryell, Jacob A. Marinsky, Lawrence E. Glendenin,
Harold G. Richter |
named
by: |
Grace Mary Coryell (1945)
|
Promethium
was named after the Greek Titan Prometheus, who, according
to Greek mythology, stole fire from Mount
Olympus to give to mankind. |
Samarium
|
atomic number: |
62
|
atomic radius: |
229 pm (Van der Waals)
|
atomic symbol: |
Sm
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
150.36
|
melting point: |
1074°C
|
electron configuration: |
[Xe]6s24f6
|
boiling point: |
1794°C
|
oxidation states: |
3,
2 |
color: |
silvery white
|
year
discovered: |
1879
|
discovered
by: |
Paul Emile Lecoq de Boisbaudran
(1838-1912) |
Samarium
was discovered in, and named for, the mineral Samarskite.
Samarskite was named in honor of Colonel Vasilii Yevgrafovich Samarskii-Bykhovets (1803-1870), Chief of Staff of the Russian Corps of Mining Engineers.
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Europium
|
atomic number: |
63
|
atomic radius: |
233 pm (Van der Waals)
|
atomic symbol: |
Eu
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
151.964
|
melting point: |
1074°C
|
electron configuration: |
[Xe]6s24f7
|
boiling point: |
1794°C
|
oxidation states: |
3,
2 |
color: |
silvery white
|
year
discovered: |
1901
|
discovered
by: |
Eugène-Anatole Demarçay
(1852-1903) |
Europium
was named after Europe. |
Gadolinium
|
atomic number: |
64
|
atomic radius: |
237 pm (Van der Waals)
|
atomic symbol: |
Gd
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
157.25
|
melting point: |
1313°C
|
electron configuration: |
[Xe]6s24f75d1
|
boiling point: |
3273°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1880
|
discovered
by: |
Jean Charles
Gallisard de Marignac (1817-1894) |
Gadolinium was
named after Finnish chemist Johan Gadolin (1760-1852).
The mineral Ytterbite was renamed Gadolinite
in 1800 also to honor him. |
Terbium
|
atomic number: |
65
|
atomic radius: |
221 pm (Van der Waals)
|
atomic symbol: |
Tb
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
157.25
|
melting point: |
1356°C
|
electron configuration: |
[Xe]6s24f9
|
boiling point: |
3230°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1843
|
discovered
by: |
Carl
Gustaf Mosander (1797-1858) |
Terbium was
named after Ytterby, a town in Sweden
near where the
mineral Ytterbite (also named after Ytterby) was discovered
in 1787 by Swedish chemist
Carl Axel Arrhenius (1757-1824). Ytterbite was later
renamed Gadolinite in honor of Johan Gadolin (1760-1852)
who discovered the element yttrium from a Ytterbite
sample. |
Dysprosium
|
atomic number: |
66
|
atomic radius: |
229 pm (Van der Waals)
|
atomic symbol: |
Dy
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
162.5
|
melting point: |
1413°C
|
electron configuration: |
[Xe]6s24f10
|
boiling point: |
2567°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1886
|
discovered
by: |
Paul Emile Lecoq de Boisbaudran
(1838-1912) |
Dysprosium was
named from the Greek word dysprositos (δυσπρόσιτος), meaning hard to get.
|
Holmium
|
atomic number: |
67
|
atomic radius: |
216 pm (Van der Waals)
|
atomic symbol: |
Ho
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
164.93032
|
melting point: |
1474°C
|
electron configuration: |
[Xe]6s24f11
|
boiling point: |
2700°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1878
|
discovered
by: |
Per
Teodore Cleve (1840-1905) |
Holmium was
named from the Latin word Holmia meaning Stockholm,
Sweden, Per Teodore Cleve's native city. |
Erbium
|
atomic number: |
68
|
atomic radius: |
235 pm (Van der Waals)
|
atomic symbol: |
Er
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
167.259
|
melting point: |
1529°C
|
electron configuration: |
[Xe]6s24f12
|
boiling point: |
2868°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1842
|
discovered
by: |
Carl
Gustaf Mosander (1797-1858) |
Erbium was
named after Ytterby, a town in Sweden
near where the
mineral Ytterbite (also named after Ytterby) was discovered
in 1787 by Swedish chemist
Carl Axel Arrhenius (1757-1824). Ytterbite was later
renamed Gadolinite in honor of Johan Gadolin (1760-1852)
who discovered the element yttrium from a Ytterbite
sample. |
Thulium
|
atomic number: |
69
|
atomic radius: |
227 pm (Van der Waals)
|
atomic symbol: |
Tm
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
168.93421
|
melting point: |
1545°C
|
electron configuration: |
[Xe]6s24f13
|
boiling point: |
1950°C
|
oxidation states: |
3,
2
|
color: |
silvery white
|
year
discovered: |
1879
|
discovered
by: |
Per
Teodore Cleve (1840-1905) |
Thulium was
named after Thule, an ancient name for Scandinavia.
|
Ytterbium
|
atomic number: |
70
|
atomic radius: |
242 pm (Van der Waals)
|
atomic symbol: |
Yb
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
173.054
|
melting point: |
819°C
|
electron configuration: |
[Xe]6s24f14
|
boiling point: |
1196°C
|
oxidation states: |
3,
2
|
color: |
silvery white
|
year
discovered: |
1878
|
discovered
by: |
Jean Charles Galissard de Marignac (1817-1894)
|
Ytterbium was
named after Ytterby, a town in Sweden
near where the
mineral Ytterbite (also named after Ytterby) was discovered
in 1787 by Swedish chemist
Carl Axel Arrhenius (1757-1824). Ytterbite was later
renamed Gadolinite in honor of Johan Gadolin (1760-1852)
who discovered the element yttrium from a Ytterbite
sample. |
Lutetium
|
atomic number: |
71
|
atomic radius: |
221 pm (Van der Waals)
|
atomic symbol: |
Lu
|
standard
state: |
solid
at 298 K (about 25°C) |
atomic weight: |
174.9668
|
melting point: |
1663°C
|
electron configuration: |
[Xe]6s24f145d1
|
boiling point: |
3402°C
|
oxidation states: |
3
|
color: |
silvery white
|
year
discovered: |
1907
|
discovered
by: |
Georges Urbain (1872-1938)
and Carl Auer von Welsbach (1858-1929)
|
Lutetium was
named after Lutetia, an
ancient Latin name for Paris. |
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