3.2 Igneous rocks
form from molten
rock
Rocks and Minerals

Rocks: naturally occurring combination
of minerals (minerals are the building
blocks for rocks)

Minerals: natural, solid substance that
has definite chemical composition and
physical structure. All rocks contain
minerals.
– The building block of rocks
Igneous Rocks
“fire rocks”
 Cooled magma or lava

– Magma= molten (melted) rock inside earth
– Lava= molten rock that reaches the surface
of earth
– **heating and cooling of in mantle layer may
lead to this formation
Igneous
2 Types of Igneous Rock
Intrusive : Igneous rock
that forms as magma cools
BELOW the Earth’s surface
(also called plutonic rock)
Example: Granite
Extrusive Rock
Igneous
rock that forms as
lava cools ON Earth’s
surface
Example: pumice and
rhyolite
Basalt forms on ocean floor
Igneous rock texture
Depends on how fast the
magma cool.
Intrusive rocks tend to have
large crystals
Extrusive rocks tend to have
smaller crystals
Intrusive Igneous rock formation
Rock Ship (New Mexico)
Basalt Columns at Yellowstone
National Park