Page 12 - Curriculum Visions Dynamic Book

Ores of iron
Iron is the second most abundant metal (after aluminium) in the Earth’s crust. However, pure iron is seldom found in nature. Most often it is found in the ore called haematite (which contains one-third of its weight as iron) and magnetite (with about two-thirds of its weight as iron). These compounds, both containing iron and oxygen, are known as iron oxides.
Magnetite
Iron is famous for its ability to act as a magnet, or to be attracted by magnets. Native (pure) iron as well as iron alloys such as steel, and iron compounds such as some iron oxides
(for example the ore magnetite) are also magnetic. The property is created because each tiny crystal of iron can behave as a magnet, organising itself into the same direction as all those crystals nearby.
The earliest knowledge of the magnetic properties of iron comes from the strongly magnetic rock known as lodestone or magnetite. The word magnetite comes from the region called Magnesia in Greece, where lodestone was mined in
ancient times.
A ball-shaped piece of
lodestone has two regions where it will attract or repel other ball-shaped lodestones. These
places are known as the magnetic poles.
 This piece of magnetite has been dipped in iron filings to demonstrate
its magnetic properties. Magnetite is Fe3O4.
Meteorites
Meteorites are one of the few highly concentrated sources of iron ore. In some meteorites iron occurs as uncombined metal (called native metal).
Because the majority of all meteorites are about nine-tenths iron, they require relatively little purifying and for this reason they were prized by earlier civilisations. Huge craters where meteorites had fallen were an obvious site to find native iron.
In ancient times, iron was known
as the “metal of heaven”. This may be because people saw meteorites fall and then discovered that they contained almost pure iron. The first iron used was definitely from meteorites like the one that created the giant Meteor Crater
in Arizona.
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