The Rock Cycle

Minerals are formed from 2 or more elements.
        e.g. Quartz = SiO₂ = Silicon + Oxygen
Rocks are composed of several minerals cemented together. There are 3 types of rocks:

1. Igneous: Greek for "fire" therefore, molten rocks.
   
   

   Extrusive Igneous: Rocks are formed on the surface by lava flows
   Intrusive Igneous: Rocks from under the surface, formed from upwelling magma which is less dense than the surrounding rocks.
   

   
   

2. Sedimentary: Formed from sediments deposited by water bodies.
   
   

   Clastic sedimentary rocks: Composed of broken pieces of other rocks.
   Chemical sedimentary rocks: Formed from the evaporation of inland seas which leave behind salts (=> Halides.)
   Biogenic sedimentary rocks: Rocks composed of the remains of living organisms.
   
   Sedimentary Process - Lithification.
   

   1) Rocks are weathered and broken down into little pieces
   2) Pieces are transported to other places where they form thick deposits
   3) Compaction occurs as new layers of sediments pile on top of each other and squish the underlying layers
   4) Cementation of grains results as the minerals which are dissolved in hot fluids (water) pump through the layers and create a solid mass of rock

   
   

   
   
3. Metamorphic: meta=change, morph=shape. Metamorphic rocks have undergone a change in shape, texture, structure and mineral composition as a result of heat and pressure. The greater the heat and pressure, the more metamorphosed (changed) a rock will be, Most rocks in the curst are metamorphic.
   
   

   Contact Metamorphic: Occur as intrusive igneous rocks force themselves in between other rocks, which are metamorphosed along the contact.
   Dynamic Metamorphic: Occur under the pressure of overlying sediments of tectonic compression forces.