igneous rock

Igneous rocks are rocks that form from the cooling and hardening of magma or lava. Magma is hot, molten rock that is found underground. Lava is magma that has erupted from a volcano and cooled on the surface of the Earth.

There are three main types of igneous rocks:

• Plutonic rocks form when magma cools and hardens underground. They are typically coarse-grained because they have time to cool slowly.
• Volcanic rocks form when lava cools and hardens on the surface of the Earth. They are typically fine-grained because they cool quickly.
• Hypabyssal rocks form when magma cools and hardens between the surface of the Earth and the crust. They are typically medium-grained.

Igneous rocks are important because they make up much of the Earth's crust. They are also important for the formation of other rocks, such as sedimentary and metamorphic rocks.

Igneous rocks are an important part of the Earth's crust.

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