Igneous Rocks

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What is an igneous rock?

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An igneous rock is a type of rock that forms from the cooling and solidification of magma or lava.

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What are the two main types of igneous rocks?

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The two main types of igneous rocks are intrusive (plutonic) and extrusive (volcanic) rocks.

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How do intrusive igneous rocks form?

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Intrusive igneous rocks form from magma that cools slowly beneath the Earth's surface.

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How do extrusive igneous rocks form?

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Extrusive igneous rocks form from lava that erupts onto the Earth's surface and cools quickly.

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What is the texture of pegmatite?

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Pegmatite is a coarse-grained igneous rock.

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What is basalt?

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Basalt is an extrusive igneous rock that forms from lava that erupts onto the Earth's surface.

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What is obsidian?

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Obsidian is a type of volcanic glass that is fine-grained and has no visible crystals.

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What is gabbro?

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Gabbro is a coarse-grained intrusive igneous rock that forms from slowly cooled magma.

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What does 'fine-grained' mean in terms of igneous rocks?

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Fine-grained igneous rocks have small crystals that are not easily visible, indicating rapid cooling.

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What does 'coarse-grained' mean in terms of igneous rocks?

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Coarse-grained igneous rocks have large crystals that are easily visible, indicating slow cooling.