How do crystals form?

Unearth the well-ordered tale of where crystals come from.

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Scientifically speaking, the word “crystal” refers to any solid that has an ordered chemical structure. This means that its parts are arranged in a precisely ordered pattern, like bricks in a wall. The “bricks” can be cubes, pyramids or more complex shapes.

Minerals are solid substances that are found naturally in the ground and can’t be broken down further into different materials. Most rocks are mixtures of different minerals. Virtually all minerals are crystals, but not all crystals are minerals. Some shops sell natural mineral crystals, such as pyrite, which is known as fool’s gold because it looks like real gold. You can also buy showy, human-made crystals such as bismuth, which is a metal that forms pretty crystals when it is melted and cooled.

How do crystals form?

Crystals grow when molecules (groups of atoms held together by chemical bonds) that are alike get close to each other. Chemical bonds form between the molecules, sticking them together. Mineral crystals won’t just start forming spontaneously – they need special conditions and a place for them to grow, called a “nucleation site”. This can be a rough edge of rock, a tiny crack or a speck of dust, where a molecule sticks and starts a chain reaction of crystallisation.