1. Chapter 5 - Igneous Rocks

2. Formation Igneous rocks form from cooling magma.
If they cool inside the Earth, they are called __________ igneous rocks and have _______ crystals.
If they cool on the surface, they are called __________ igneous rocks and have _______ crystals.
intrusive
large
extrusive
small

3. Crystal Size
This piece of obsidian cooled so _____ on the surface that it did not have time to form any crystals.
fast

4. Crystal Size
This piece of rhyolite also cooled on the surface very fast and has ______ crystals.
small

5. Crystal Size
This piece of granite cooled _______ inside the Earth and has ______ crystals.
slowly
large

6. Classification is based on crystal size and composition.

7. magma
igneous rock
lava
extrusive
intrusive

8. extrusive; small grain size
gabbro has a large grain size
intrusive; its large grain size