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Contents of 4.2 How are igneous rocks classified?

4.2 How are igneous rocks classified?

• Composition:
• As magma cools, minerals will solidify at various temperatures
• What solidifies depends on the composition of the magma
• Most magma is largely silica (45 to 80%) with oxides of Al, Mg, Fe, Ca, Na, K - and other minor elements
• So most igneous rocks are made of silicates