Minerals are the fundamental components of the Earth. ‘The mineral world’ describes the fields of mineralogy and crystallography that study them. There are approximately 4,400 known minerals, but the ‘big ten’ minerals that are most abundant in the rocks of the Earth’s crust and Upper Mantle are calcite, quartz, olivines, pyroxenes, amphiboles, muscovite, biotite, orthoclase, albite, and anorthite. The two essential characteristics of any mineral are its chemical composition and its crystal structure. Minerals can be assigned to one of seven crystal classes depending on their elements of symmetry. There is further subdivision into 32 crystal classes. Minerals are classified by chemical composition into mineral groups such as silicates, and carbonates.