All the metals we use are taken from the Earth. Most of them are found in rocks, combined with other substances, while some, like gold and copper are found as pure metal. Many of the ‘fossil fuels’ we use, like coal, gas and oil, are also taken from the Earth. Coal is usually dug out of the ground while gas and oil are extracted by drilling deep holes in the Earth.
Rocks in the Earth’s crust can often be used for specialized jobs. For example, one rock called ‘mica’ is found in thin transparent sheets. It can be used to make windows for high-temperatures ovens, where glass would melt.
How coal was formed
Coal has formed over millions of years from the remains of ancient forests growing on swamps.
As forest trees and plants died, they fell into the swamps forming layers of dead vegetation. Later, sedimentary rocks formed on top of these layers.
The pressure caused by the rocks made the layers of vegetation denser and harder and formed them into a solid rock – coal.
Coal is a fossil fuel often mined from underground.