1. Igneous Rocks

2. What are they?
Rock made from cooled LAVA or MAGMA.

3. Classification Igneous Rock is classified in 3 ways… Texture
Origin (where it formed)
Mineral Composition

4. Texture Coarse Grained = large grains, cooled slowly
Fine Grained = small grains, cooled fast
Porphyritic = small AND large grains (resembles jello w/fruit in it)

5. Course Grained
Granite = Intrusive Igneous rock
Fine Grained
Basalt = Extrusive Igneous rock
Porphyritic Texture
Porphyritic Granite

6. Origin
Intrusive – formed UNDERGROUND. It cools slowly so it will have large grains.
Extrusive – formed ABOVE GROUND. It cools fast so it has small grains.

7. Mineral Composition How much silica is in the magma/lava?
High silica content = light colored = Mafic
Low silica content = dark colored = Felsic
High Silica Content Low Silica Content
Mafic Igneous Rock Felsic Igneous Rock