1. Igneous Rock
Chapter 4 Section 2

2. Igneous rocks
Igneous rocks are classified by their origin, texture, and mineral composition

3. Origin and Texture
Extrusive rock- rock that forms from lava on or near Earth’s surface
- they have small crystals and
fine-grained texture due to quick
cooling
Andesite

4. Origin and Texture - Some cool so fast that no crystals
form and rock has a glassy texture
Obsidian

5. Origin and Texture
Intrusive rock – rock that forms from magma beneath Earth’s surface
- they have large crystals and a coarse-
grained texture due to slow cooling
Granite

6. Mineral Composition Minerals low in silica are dark colored and dense
Minerals high in silica are usually light colored and less dense

7. Uses of Igneous Rock
Bridges
Statues
Fortresses

8. Uses of Igneous Rock Countertops Gravel Cleaning, polishing, and
cutting tools
Streets