Minerals are naturally occurring substances formed by geological processes. They are found in the uppermost layer of the Earth’s crust. Some minerals are formed from molten magma, such as diamond, mica and feldspar. Some are found in places such as in rocks, in sand or in gravels. There exist more than 2800 different varieties of minerals on the Earth. Minerals are generally identified on the basis of colour, transparency, lustre, streak, crystal form, cleavage and hardness. Most of the minerals have a crystalline structure. Minerals are divided into two major groups: metallic and non-metallic. Metallic minerals include: iron, cobalt, bauxite, etc. Non-metallic minerals include: mica, feldspar, salt, etc. The third category of mineral is energy mineral that constitutes coal, petroleum and natural gas, although they are categorised as fossil fuels.
Minerals
