By Paige Black

 A rock is a naturally occurring solid mixture of one or more minerals, or organic matter.  Rocks are classified by how they are formed, their composition, and texture.  Rocks change over time through the rock cycle.

 Igneous Rocks  Examples: granite, basalt, pumice, flint  Sedimentary Rocks  Examples: limestone, chalk, sandstone  Metamorphic Rocks  Examples: slate, marble, quartzite

 These are rocks that solidified directly from magma.  Magma can form:  When rock is heated  When pressure is released  When rock changes composition  Magma freezes between 700˚C and 1,250˚C.  Magma is a mixture of many minerals.

 Types of Composition:  Felsic- light colored rocks that are rich in elements such as aluminum, potassium, silicon, and sodium  Mafic- dark colored rocks that are rich in calcium, iron, and magnesium, poor in silicon  Coarse-grained- takes longer to cool, giving mineral crystals more time to grow  Fine-grained- cools quickly with little to no crystals

 Types of Formation:  Intrusive- magma pushes into surrounding rock below the Earth’s surface  Extrusive- magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed

 The rocks are formed when igneous rocks are eroded as a sediment under the sea.  Sediments are moved from one place to another.  Sediments are deposited in layers, with the older ones on the bottom.  The layers become compacted and cemented together.

 Three Types:  Clastic- made of fragments of rock cemented together with calcite or quartz o Example: Sandstone  Chemical- minerals crystallize out of solution to become rock o Example: Halite (Rock Salt)  Organic- any accumulation of sedimentary debris caused by organic processes o Example: Coal

 Means “change in form”  Changes with temperature and pressure, but remains solid  Usually takes place deep in the Earth  Make up a lot of the Earth’s crust

 Two Types:  Contact- when magma is injected into the surrounding rock solid. Increased temperature changes the composition of the rock, minerals are changed into new minerals.  Regional- changes in great masses of rock over a wide area. Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressure.

 Two Types of Texture:  Foliated- contain aligned grains of flat minerals o Example: Slate  Non-foliated- mineral grains are not arranged in bands or plains o Example: Marble

 Igneous  Sedimentary  Metamorphic

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