What are the 3 main differences between intrusive and extrusive igneous rocks?
Extrusive igneous rocks come from lava, forming at the surface of the Earth and cooling quickly, meaning they form very small crystals. Intrusive igneous rocks come from magma, forming deep underground and taking longer to cool, meaning they form larger crystals.
What is the difference between extrusive and intrusive rocks give an example of each?
Intrusive rocks are made up of enormous crystals whereas extrusive rocks have tiny crystals that can be seen only with a microscope. Granite is the best example of intrusive rocks whereas the basalt is a fine example of extrusive rocks. Images Courtesy: Basalt by Zureks (CC BY-SA 3.0)