Igneous Rocks

Formed from the cooling of lava or magma

Igneous Rocks are Divided into Two Groups

Intrusive Extrusive

Intrusive Igneous

• Formed from cooling MAGMA• Forms deep INSIDE the Earth’s crust• Crystals have more time to grow, so they are

LARGER• Described as COARSE-GRAINED

Intrusive Igneous Examples

Granite Syenite

Intrusive Igneous Examples

Diorite Gabbro

Extrusive Igneous

• Formed from cooling LAVA• Forms OUTSIDE the Earth• Crystals have LESS time to grow, so they are

SMALLER OR NON-EXISTANT• Described as FINE-GRAINED

Extrusive Igneous Examples

Obsidian Scoria

Extrusive Igneous Examples

Basalt Pumice

Quiz Question 1

• This is an extrusive igneous rock

• It has a glassy texture

• It has been used throughout history to make knives and arrow heads.

Quiz Question 1

• This is an extrusive igneous rock

• It has a glassy texture

• It has been used throughout history to make knives and arrow heads.

• Answer: Obsidian

Quiz Question 2

• Can you name this extrusive igneous rock that is often used in foot-care?

Quiz Question 2

• Can you name this extrusive igneous rock that is often used in foot-care?

• Answer: Pumice

Quiz Question 3

• This is an intrusive igneous rock

• It has coarse-grained texture

• It is composed of the minerals: quartz, feldspar, and mica

Quiz Question 3

• This is an intrusive igneous rock

• It has coarse-grained texture

• It is composed of the minerals: quartz, feldspar, and mica

• Answer: Granite