Igneous Rock Chapter 4 Section 2
Dec 29, 2015
Igneous Rock
Chapter 4 Section 2
Igneous rocks
Igneous rocks are classified by their origin, texture, and mineral composition
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
Origin and Texture
- Some cool so fast that no crystals
form and rock has a glassy texture
Obsidian
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
Mineral Composition
• Minerals low in silica are dark colored and dense
• Minerals high in silica are usually light colored and less dense
Uses of Igneous Rock
Statues
Fortresses
Bridges
Uses of Igneous Rock
CountertopsGravel
StreetsCleaning, polishing, andcutting tools