Geology Reference
In-Depth Information
B.2.41 Nickel
The bulk of nickel mined comes from two types of ore deposits. The first are la-
terites where the principal ore minerals are nickeliferous limonite
20
and garnierite
Ni
3
MgSi
6
O
15
(OH)
2
6(H
2
O) . The second are magmatic sulphide deposits where
the principal ore mineral is pentlandite Fe
2
4:5
Ni
4:5
S
8
. Arsenide ores such as ni-
ckeline NiAs or gersdor
te NiAsS can be also found. Ni can also appear in
the crystalline structure of many other minerals including pyrrhotite, chalcopyrite,
pyrite, ilmenite or magnetite.
Nickel is a transition metal that belongs to the same group as iron. It is mainly
used in the preparation of alloys, for reasons relating to strength, ductility and
resistance to corrosion. About 65% of the nickel consumed in the Western world
is used to make stainless steel. The remainder is divided up into the alloy steels,
rechargeable batteries, catalysts, coinage, foundry products and plating.
B.2.42 Niobium
Niobium, sometimes called columbium, is a rare soft transition metal, used mainly
for the production of high-temperature resistant alloys and special stainless steels.
Small amounts of niobium impart greater strength to other metals. The applications
of those alloys are in nuclear reactors, jets, missiles, cutting tools, pipelines, super
magnets, surgical implants and welding rods. Niobium is additionally used as a
superconductor when lowered to cryogenic temperatures.
Niobium has been mainly mined as columbite FeNb
2
O
6
. Two other impor-
tant Nb-containing minerals are euxenite (Y;Ca;Ce;U;Th)(Nb;Ta;Ti)
2
O
6
and py-
rochlore Na
1:5
Ca
0:5
Nb
2
O
6
(OH)
0:75
F
0:25
, the latter is currently its most important
ore. Due to its similarities to tantalum, minerals that contain niobium also contain
tantalum, so that columbite is referred to as tantalite when tantalum preponderates.
B.2.43 Nitrogen
Nitrogen is a common inert gas and an essential element in most of the substances
that make up living organisms, including proteins. Despite its ready availability
in the atmosphere, constituting 78% of air by volume, nitrogen is relatively scarce
in the continental crust. The only major minerals are KNO
3
(nitre, salpetre) and
NaNO
3
(sodanitre, nitratine). Both are widespread.
Its main application is as a component in the manufacture of ammonia, subse-
quently used as a fertiliser and in the production of nitric acid. It can be used also
as a refrigerant for the freezing of and transporting of food products.
20
Nickeliferous limonite is the term used to describe poorly crystalline nickel-bearing ferric oxides
of which the main constituent is goethite Fe
3+
OOH.
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