Igneous Rocks

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Igneous Rocks
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What are they?

• Rock made from cooled LAVA or MAGMA.

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Classification

• Igneous Rock is
• classified in 3 ways
• Texture
• Origin (where it formed)
• Mineral Composition

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Texture

• Coarse Grained large grains, cooled slowly
• Think about it. If it cools over a long time
  the grains have time to get big! ?
• Fine Grained small grains, cooled fast
• Think about it If it cools over a short time
  the grains dont have time to get big!?

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Grain Size Have.

• SPECIAL NAMES

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Igneous Rock Formation

• Intrusive formed UNDERGROUND. It cools slowly
  so it will have large grains (coarse).
• Extrusive formed ABOVE GROUND. It cools fast
  so it has small grains (fine).

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Fine Grained Basalt Extrusive Igneous
rock Course Grained Granite Intrusive
Igneous rock
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Mineral Composition

• How much silica is in the magma/lava?
• Low silica content dark colored Mafic
• High silica content light colored Felsic

High Silica Content Low Silica
Content Felsic Igneous Rock Mafic Igneous Rock
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Big Crystals
Small or No Crystals
Lighter
Darker
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