1. The Earth's crust is 5 percent iron and in some areas the element concentrates in ores that contain as much as 70 percent iron.

2. When you compare iron and steel with something like aluminium, you can see why it was so important historically. To refine aluminium, you need access to huge quantities of electricity. Furthermore to shape aluminium you have to either cast it or extrude it. Iron however is much easier to manipulate.

3. The only real problem with iron and steel is rust. Fortunately you can control rust by painting, galvanizing, chrome plating or coating the iron with a sacrificial anode, which corrodes faster than the stronger metal.

4. Iron is a shiny, bright white metal that is soft, malleable, ductile and strong. Its surface is usually discoloured by corrosion, since it combines readily with the oxygen of the air in the presence of moisture.

5. The oxide that is produced is crumbly and soft, giving no protection to the base metal, which eventually rusts away.

6. In absolutely dry air, it does not rust.

7. At room temperature, iron is in the form of ferrite, or α-iron, a body-centred cubic structure. The density of α-iron is 7.86 g/cc.

8. At 910°C it changes to γ-iron, which is face-centred cubic and somewhat softer.

9. Melting point of iron is 1535 degree Celsius and boiling point is 3000 degree Celsius.

10. The specific heat of iron is about 0.107 cal /g-K and electrical resistivity is 9.71 μΩ-cm.

This is how the Iron is most important material for engineering applications.