Download Igneous Rock

Igneous Rock
Characteristics of Igneous Rock
Igneous rock is any rock that forms
from magma or lava.
Origin
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
• Intrusive rock is igneous rock that formed
when magma hardened inside Earth.
*** hint: think intrusive inside ***
Example: Granite
(Stone Mountain)
Texture
• Intrusive and extrusive rocks usually have
different textures.
Intrusive rocks have large crystals.
Extrusive rocks have small crystals.
Intrusive
Extrusive
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.
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.