1. Igneous Rock

2. Characteristics of Igneous Rock
Igneous rock is any rock that forms from magma or lava.

3. Origin Example: Basalt
Geologists classify igneous rock according to where it formed.
Extrusive rock is igneous rock formed from lava that erupted onto Earth's surface.
*** hint: think extrusive exits ***
Example:
Basalt

4. Intrusive rock is igneous rock that formed when magma hardened inside Earth.
*** hint: think intrusive inside ***
Example: Granite
(Stone Mountain)

5. Texture Intrusive and extrusive rocks usually have different textures.
Intrusive rocks have large crystals.
Extrusive rocks have small crystals.
Extrusive
Intrusive

6. Mineral Composition
Most of Earth's minerals contain silica, a material formed from oxygen and silicon.
Lava that is low in silica usually forms dark-colored rocks such as basalt.
Magma that is high in silica usually forms light-colored rocks, such as granite.

7. Uses of Igneous Rock
Many igneous rocks are hard, dense, and durable. For this reason, people throughout history have used igneous rock for tools and building materials.