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Igneous rock
Igneous rock
Science • Earth's resources
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The melting point of rock is very high.
Melted rock is called either lava (on Earth's surface), or magma (underground).
Extrusive igneous rock forms outside Earth's crust, while instrusive igneous rock forms inside the crust.
Some substances form crystals when they freeze.
Crystal size depends on the rate at which melted rock cools.