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What are Igneous Rocks?

Rocks formed from the cooling of hot magma
are called igneous rocks.

Igneous rocks first formed when the Earth cooled from
molten state about 4 billion years ago. Igneous rock is
still being made today by the
process of tectonic activity.

How can Igneous Rocks be Identified?

Igneous rocks contain randomly arranged interlocking crystals.
The crystal size depends on the rate of cooling.
When hot magma is cooled quickly it makes basalt
and when it is cooled slowly it makes granite.
Igneous rocks do not contain fossils because the rock forms
at a high temperature which would destroy any living organisms.

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