Geology Reference
In-Depth Information
50% of all Cu deposits; copper glance (chalcocite) Cu
2
S; cuprite Cu
2
O and mala-
chite Cu
2
CO
3
(OH)
2
. Bornite Cu
5
FeS
4
, azurite Cu
3
(CO
3
)
2
(OH)
2
and covellite
CuS represent some of its minor ores. Native copper is found occasionally.
Copper is one of the coinage metals with gold and silver because of its former us-
age. It is an excellent conductor of heat and electricity and therefore is a key metal
in the electric and electronic industry. Electrical uses of copper can be found in
power transmission and generation, building wiring, telecommunication and elec-
trical and electronic products. All these account for about three quarters of its
total use. Further applications of copper are in construction, including roofing and
plumbing and in industrial machinery such as heat exchangers. It is also used in
the manufacture of brass and is commonly alloyed with zinc, tin, nickel, lead and
aluminium.
B.2.18 Dysprosium
Dysprosium is a key alloying component (up to 3-6%) of NdFeB permanent
magnets. It is used to improve their corrosion resistance and raise coercitivity which
avoids any demagnetisation occurring in moderately high temperature working mo-
tors. It also increases strength and corrosion resistance. Alloyed with terbium,
it makes up Terfenol-D which is in turn used for multiple applications in sensors,
transducers and actuators. Thanks to dysprosium's high magnetic susceptibility it
is also used in data storage applications. Dysprosium oxide-nickel cermets are used
in control rods for absorbing neutrons in nuclear plants, whilst dysprosium doped
crystals of calcium fluoride or calcium sulphide are used in dosimeters for measuring
ionising radiation that activates Dy luminescence. Additionally, dysprosium is em-
ployed in laser materials, high intensity light sources and in infrared phosphors. In
medical applications Dy 165 is injected into joints to treat rheumatoid arthritis.
Its rarity amongst all REE and its extensive used in a wide range of applications
including as permanent magnets in green cars, computer drives, home appliances
and wind turbines makes this element not only a crucial but critical resource. Dys-
prosium is expected to have a 0.9% share of the world REE supply by 2015. For
more details see Sec. B.2.50.
B.2.19 Erbium
Erbium is a relatively scarce heavy REE. It is used in glass, ceramics and cubic
zirconia for pink colouring. In fiber optics, it is used to reduce attenuation. Erbium
doped fiber amplifiers (EDFA) enable optical signals to be substantially amplified in
optical fibers (bit rate '10 Gbps). Co-doped fiber lasers with erbium and ytterbium
offer a high power output and good quality beam that can be used for marking,
printing, fine welding, fast metal cutting and other micromachining applications.
Erbium is used as a dopant in solid state lasers and like holmium has a variety of
medical applications. It is particularly useful in laser rejuvenation skin resurfacing.
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