What are rocks made of?
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Transcript
You look closely at a rock and see tiny sparkly bits and different colors - what is a rock actually made of?
Look closely at a rock, and you'll see tiny bits and patterns in different colors. Those are minerals, different kinds of tiny materials mixed together.
Deep inside the earth, hot melted rock cools and its tiny bits stick together to form rock. Sand and mud can also pile up in layers and harden into rock over time.
Sometimes rocks get pressed and warmed for a very long time deep underground. That changes how the tiny bits line up, turning it into a whole new kind of rock.
Rocks are made of minerals, and they can change shape deep inside the earth.
For grown-ups: the science
Rocks are made of tiny bits called minerals.
Rocks are mostly made up of clusters of minerals. There are igneous rocks that form when magma cools and hardens, sedimentary rocks that form when sand or mud settles and hardens, and metamorphic rocks that form when existing rocks change under heat and pressure. Some rocks are made of almost entirely one type of mineral.