1. 3 Groups of Rocks Igneous : intrusive & extrusive
Sedimentary : clastic, organic, chemical
Metamorphic : foliated & nonfoliated

2. How are Igneous Rock Classified ?
Origin
Texture
Mineral
composition

3. ORIGIN
Extrusive : formed from lava that erupted onto Earth’s surface. Basalt is the most common example.
Intrusive : formed when magma hardened beneath Earth’s surface. Granite is the most abundant intrusive rock in the continental crust.

4. Texture Fine Grain : rapid cooling with small crystals ex. Rhyolite
Coarse Grain : slow cooling with large crystals
ex. Gabbro
Glassy : fastest cooling with no crystals
ex. Obsidian
Porphyritic : large crystals surrounded by fine grain crystals ex. Porphyry

5. Mineral Composition Low silica content results in dark colored rocks
ex. Basaltic – Andesite
extrusive igneous
High silica content results in light colored rocks
ex. Grantic – Gniess
intrusive igneous

6. Sedimentary Rocks

7. How do Sedimentary Rock Form ?
Weathering and Erosion
Deposition
Compaction
Cementation

8. 3 Groups of Sedimentary Rocks
Clastic : forms when rock fragments are squeezed together
Ex. Shale
Ex. Sandstone
Ex. Conglomerate

9. Organic : forms from the remains of plants and animals
Ex. Coal
Ex. Limestone

10. Chemical : forms when minerals that are dissolved in a solution crystallize
Ex. Halite
Ex. Gypsum

11. Metamorphic Rock
Forms from other rocks deep beneath the Earth’s surface which are under the influence of Heat & Pressure
Foliated : has layers
Nonfoliated : no layers

12. Foliated Metamorphic
Slate
Gneiss
Schist

13. Nonfoliated Metamorphic
Quartzite
Marble
Soapstone

14. The Rock Cycle