All metals are mined from the Earth, and many require additional refinement before they are suitable for the many different tasks for which they are required. Steel, for example, is usually worked through a furnace to remove impurities before it is suitable for further refinement and eventual use in construction or engineering.
Only a few very precious metals, such as gold, require little refinement when mined. Most, like iron and steel, are mined and then processed to become functional.
Processing metals usually involves heating the ore until it melts to allow for the removal of slag before the core metal is refined. This process is known as puddling, and it is strenuous and often dangerous work.