Igneous Rocks

Explain how the cooling rate of magma affects the texture of igneous

rock.

Igneous Rocks

• Igneous Rocks • Igneous is Latin for FIRE• Forms when molten

rock cools and hardens• Can form deep in Earth

or on surface

Igneous Rocks

• Two types:– Intrusive igneous rock • Rock formed from cool

and solidification of magma beneath Earth’s surface

• Slow cooling magma = large mineral crystals

• Large crystals = course (rough) grained rock

Igneous Rocks– Extrusive igneous rock • Rock that forms as

result of volcanic activity or cools on Earth’s surface

• Fast cooling = small mineral crystals

• Small crystals = fine (smooth) grained rock

Igneous Rocks

• Summary:– What is an igneous rock?– What is the difference between extrusive and

intrusive igneous rocks?

29 November 2011

Objective: Explain how the cooling rate of magma affects the texture of igneous rock.

OUTROWhat’s the difference between intrusive and extrusive?