the same mineral that makes steel.
steel and iron
steel bridges are made out of steel OBVIOUSLY !!!
John W. Fisher has written: 'Fatigueand fracture in steel bridges' -- subject(s): Bridges, Iron and steel, Fatigue, Fracture, Iron and steel Bridges, Steel, Structural, Structural Steel
Today they are made of a type of plastic. They use to be chrome or steel.
Iron is important because it makes steel for steel is made of 98% iron. It is also used in buildings, bridges and other objects that need to be strong.
Steel
nothing
steel
iron and steel
Hardness
yes but a very rare mineral
yes but a very rare mineral