• Magma cools to form igneous rocks.
  • Two factors determine what type of rock forms.
  • The composition of the magma determines if the rock is mafic, felsic, or intermediate.
  • The rate of cooling determines the texture of the rock.
  • Many mountain ranges are made of granite.
  • Volcanoes are also found where you can't see them.
  • Oceanic crust is mostly basalt and gabbro.
  • The mantle is peridotite, a type of basalt.
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