1. Igneous Rocks

2. Igneous Rocks are formed from fresh magma (notes)
Formed when molten material pushes up into the crust or through it onto the surface.
Contain various different minerals.
Minerals are arranged randomly in interlocking crystals.

3. In* trusive rocks occur when magma cools very slowly underground.
INTRUSIVE (notes)
In* trusive rocks occur when magma cools very slowly underground.
Exposed when surrounding rocks are weathered away
They have a coarse texture because they have large crystals.
Plutonic

4. Intrusive Granite is an intrusive rock. Notice the large crystals.
Very hard, used in building

5. EXTRUSIVE (notes)
Extrusive rocks are formed when magma spills out onto the surface as lava and cools.
They have a fine texture because they are made of very small crystals.
Volcanic

6. Extrusive
Basalt is formed on top of the earth’s crust after bursting out of a volcano.
It cooled quickly, so it has much smaller crystals than granite.

7. Extrusive
Sometimes extrusive rocks cool so quickly they don’t form any crystals at all. (notes)
Obsidian has a glassy texture.

8. Composition (notes)
Felsic – light in color, high in aluminum. Less dense.
Mafic – dark in color, high in magnesium and iron. More dense.

9. ESRT