In GCSE Science students will look at some of the materials used in building, such as limestone or metals. This is the third of seven quizzes on that topic - and the second of two on extracting metals from the ground - and it looks in particular at extracting reactive metals.
The rocks of the Earth's crust contain metals in the form of metal compounds like iron oxide and aluminium oxide. These are often mixed with other substances and where they occur in a high enough concentration, we call them ores. An ore is a rock from which a metal can be extracted economically.
Ores are mined from the ground on a large scale. They often need to be concentrated even more before the metal is extracted and purified. The economics of using a particular ore may change over time. For example, as a metal becomes rarer, an ore that only has a low concentration of the metal may be used when it was previously considered too expensive to mine.