The building blocks of Earth
Most rocks in the Earth’s crust are composed of only eight of the chemical elements – oxygen, silicon, aluminium, iron, calcium, magnesium, sodium and potassium. Two of these elements, silicon and oxygen, combine in silicates, which make up 75 per cent of the Earth’s rocks. Most minerals are crystalline – the atoms that make up the crystals are arranged in an orderly fashion. It is the job of the mineralogist to understand what minerals are, where they are to be found, and what they can be used for.
Elements in the Earth’s crust
The crust, or lithosphere, is the outermost solid layer on the Earth’s surface. Oxygen atoms are so large that almost all
