Geology Reference
In-Depth Information
B.2.47 Platinum
Platinum gives the platinum-group metals (PGM) its name. The group comprises of
platinum, palladium, rhodium, ruthenium, iridium and osmium. Platinum generally
occurs associated with the other metals of its group but can occur in native form
or as sulphides or arsenides in Ni, Cu and Fe sulphide ores. Three-quarters of the
world's production comes from South Africa, where it occurs as cooperite. It is also
extracted as a byproduct from copper-nickel ores such as chalcopyrite, pyrrhotite
and pentlandite or with chromite.
It has outstanding catalytic properties and its resistance is well suited for making
fine jewellery. Platinum and its alloys are also used in surgical tools, laboratory
utensils, electrical resistance wires and so on. The glass industry uses platinum for
optical fibers and liquid crystal glass displays.
B.2.48 Potassium
Potassium is a soft, silvery-white metal, member of the alkali group. It is a very
abundant element on Earth. Most of it occurs as minerals including feldspars and
clays. Potassium is leached from these by weathering processes, which explains why
the sea contains substantial amounts. Important ores are sylvite KCl, carnallite
KMgCl
3
6(H
2
O) and alunite KAl
3
(SO
4
)
2
(OH)
6
.
Most commercial potassium goes into fertilisers. Potassium carbonate is used in
glass manufacture for the making of televisions. Potassium hydroxide, meanwhile,
is used to make liquid soaps and detergents. Additional applications of other potas-
sium compounds are found in the pharmaceutical industry, photography and for
the manufacturing of iodised salts.
B.2.49 Praseodymium
Praseodymium belongs to the REE group and is used as a component of the
Nd Fe B permanent magnets. Praeodymium oxide protects against yellow
glare and UV light, and gives a metallic yellow colour to glass, plastic, enamels and
ceramics. As it filters out harmful intense light it is also used in welders' goggles. It
can be found in solid state lasers and is a core material for carbon arc lighting. In
metallurgy, together with zinc, it is employed in high performance magnesium alloys
for die-cast applications. Alloyed with nickel, it presents a strong magnetocaloric
effect, whose future demand will presumably increase as does new emergent refrig-
eration technology. Praseodymium is expected to have 5% share of world REE
supply in 2015. For more details see Sec. B.2.50.
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