1. The Different Types of Rock

2. Igneous Rocks
Form when hot melted rocks or minerals cool down (called crystallization)
Igneous = formed by fire
Classified/recognized by texture which is caused by how fast they cool down
Can be Intrusive or Extrusive

3. Intrusive – form INSIDE the Earth Extrusive – form ON the Earth
Form from magma (liquid rock underground)
Cool slowly, forms large crystals
Coarse (large) texture
Form from lava (liquid rock above ground)
Cool quickly, forms small crystals
Fine (small) texture
Can be further divided:
1. Vesicular – has holes in it from escaping gases, very light weight
2. Glassy – cools so fast no crystals form, shiny

4. Metamorphic Rocks Are called “changed” rocks
They begin as one rock and change into another
Heat and Pressure cause chemical changes in the minerals within the preexisting rocks
Often have bands (layers) or minerals
Can be foliated or non-foliated

5. Foliated (bands of different colors) Non-foliated (no bands)
May not always look like bands but can see different patterns for each mineral
No real banding or patterns

6. Sedimentary Rocks
Formed when sediment (rock particles such as sand, pebbles, clay, etc.) is cemented together
Sediments settle (drop to the bottom) and then become solid when air and water are squeezed out
Heaviest sediments fall first – you can see the different layers within the rocks
Often have Fossils and shells of animals in them
Can be clastic or Non-clastic

7. Clastic
Non-clastic
Made up of pieces of rocks that have been weathered, eroded & deposited
Weathering – breaking up rocks into pieces
Erosion – transported somewhere else
Deposited – dropped somewhere, settling
Can be chemical or organic
Chemical form when water evaporates and minerals are left behind
Organic – form from plants and animal remains