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

How are Igneous Rock Classified ? Origin Texture Mineral composition

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.

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

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

Sedimentary Rocks

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

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

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

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

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

Foliated Metamorphic Slate Gneiss Schist

Nonfoliated Metamorphic Quartzite Marble Soapstone

The Rock Cycle