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