What are rocks made of?

Pick up a stone and look closely. Do you see little flecks and sparkles? A rock is not just one grey lump. It is made of tiny pieces packed tightly together. What are those pieces?

Rocks are made of minerals

The little bits inside a rock are called minerals. Minerals are nature’s building blocks. Some are shiny, some are white, some are dark. When lots of minerals squeeze together, they make a rock. That is why a single stone can have so many colours and sparkles in it!

Rocks are made in different ways

Not every rock is made the same way.

Some rocks start as super-hot melted rock deep under the ground. When it cools down, it turns hard and solid — like jelly setting in the fridge, only made of stone.

Other rocks form when layers of sand, mud or tiny shells pile up at the bottom of a lake or sea. Over a long, long time the layers get pressed together until they squash into stone.

Slow, slow, slow

Here is the amazing part: making a rock takes a very long time — longer than a person, longer than a whole forest. Rocks are some of the oldest things you can ever hold in your hand.

Wonder fact: Some rocks on Earth are over 3 billion years old — far older than the dinosaurs!