Igneous Rocks Chapter 3.2 ©Mark Place, 2007-2008 www.LearnEarthScience.com

Formation Form when magma or lava cools and hardens. Magma: inside Earth Lava: outside Earth

Where they are made? http://www.indiana.edu/~geol116/week3/maggran.mov INTRUSIVE IGNEOUS ROCKS Inside Earth http://www.indiana.edu/~geol116/week3/maggran.mov

EXTRUSIVE IGNEOUS ROCKS * Outside Earth

Texture of the Rocks? Igneous rocks have different textures. Texture is how a rock looks and feels. Texture is based on the size of crystal grains in the rock.

Crystal Size is Determined by: cooling time

crystal size cooling time

Large Crystals Indicate long cooling time Small Crystals Indicate short cooling time

SLOW cooling-large enough crystals to see with your naked eye Intrusive Extrusive form on or near the surface QUICK cooling -small or no crystals form below the surface SLOW cooling-large enough crystals to see with your naked eye

Characteristics used to classify igneous rocks

Texture glassy } extrusive fine

Texture coarse } intrusive very coarse

Porphyrytic: When you have a mix of large and small crystal grains. This rock experienced two cooling situations.