RocksGroup2

__What are rocks?__ Rocks are solid mass that forms from one(or more) mineral(s) above and below the earth's crust by either solidification, metamorphism or lithificaion an cementation. __What are the different types of rocks?__ There are three different types of rocks, igneous, sedimentary and metamorhic. __What makes them different?__ The factor that makes them different is the way they were formed. __Igneous rocks are__ formed from the solidification and crystallization of magma(below the surface) and lava(above the surface).They can be intrusive or extrusive. __Intrusive__ - They are formed inside the earth's crust and have larger crystals than extrusive rocks. The relation between the size of the crystals and the depth is the greater the depth the larger the crystals and vice versa. __Extusive__ - They are formed outside of the earth's crust and cool much faster than intrusive rocks. Some cool instantaneously such as obsidian __Sedimentary rocks are__ formed from the compaction and cementation of sediments, which are solid fragments of inorganic or organic material that come from the weathering of rock and are carried and deposited by wind, water, or ice. The three types of sedimentary rocks are clastic, chemical and organic. __Clastic__ - They are formed from the mechanic weathering of igneous and metamorphic rocks.

__Chemical__ - They are formed when dissolved materials precipitate from solution. __Organic__ - They form when plant and animal debris accumulate.

__Metamorphic rocks are__ rocks that form from the metamorphism of igneous and sedimentary rocks. Metamorphism is the solid-state recrystallization of igneous and/or sedimentary rocks because of changes in physical and chemical conditions, mainly heat, pressure, and chemicals. __Foliated rocks__ - Have a layers that are produced by exposure to heat and directed pressure. __Non-foliated rocks__ - Do not have layers.