What are igneous rocks? All rocks on Earth were initially igneous. Igneous rocks form as liquid magma cools, forming crystal structured rocks. There are many different types of igneous rocks. Ignis means fire (ignite, ignition)

Either deep within Earth or on Earth’s surface. Where do they form? Either deep within Earth or on Earth’s surface.

http://library.thinkquest.org/05aug/00461/igneous.htm

Two Types of Igneous Rocks Scientists divide igneous rocks into two different categories. Those which were cooled below the surface are called intrusive rocks Those which cooled on the surface are referred to as extrusive rocks.

Extrusive- Exit, Exoskeleton,exterior Igneous Rocks- Word Connections Extrusive- Exit, Exoskeleton,exterior Intrusive-inside, intrude,interior Coarse- rough Fine - smooth

Intrusive/Inside Granite(Intrusive) most common -intrusive igneous rocks. forms when a pocket of magma slowly cools down Turns into solid rock beneath earth’s surface Coarse/large grain crystals You can see the crystals

Intrusive If you look closely at a piece of granite you will see little flecks of white, black, gray, and sometimes pink. These flecks of color are crystals Coarse Grained Crystals

Extrusive Igneous rock formed from lava that has flowed out onto the Earth’s surface. Solidifies fast Cools rapidly Small/fine grains Ex-basalt/obsidian Can’t see the crystals

http://library.thinkquest.org/J002289/rocks.html

Obsidian(Volcanic Glass) Extrusive Obsidian(Volcanic Glass)

Name of Rock Basalt Granite Type of Igneous extrusive intrusive Texture Glassy or fine Course,rough Crystals Small crystals Large Crystals

Petraologists study igneous rocks Field observations Careers in Science Petraologists study igneous rocks Field observations Laboratory studies Geochemical analyses and experiments