Igneous rocks are formed by the cooling, solidification, and crystallisation of molten magma either beneath the surface or on the surface of the Earth. When magma cools slowly beneath the surface, it forms intrusive igneous rocks with large crystals. When it erupts and cools quickly on the surface as lava, it forms extrusive igneous rocks with fine grains.
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Question
Describe how igneous rocks are formed.
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Solution
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