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Rocks

Igneous Rocks - Granite.

When molten magma cools slowly, it can crystallise to form granite.

If molten magma is forced upwards from the mantle but does not
reach the surface, it will cool slowly in the surrounding crust.
A light coloured rock composed of large
randomly arranged interlocking crystals will form.
Granite is an example of this type of rock.
It is called an intrusive igneous rock because it forms inside the crust.

It is generally true that fast cooling
will result in a large number of small crystals,
and slow cooling will result in a smaller number of large crystals.

Earth movements in the crust
can cause the granite to slowly reach the surface.
This is called uplift, and can happen with any kind of rock.

See also uses of granite.

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