Rock Classification

What is a Rock? A MIXTURE OF MINERALS

All are rocks but look different

Reasons?

All are from cooled lava diorite All are from cooled lava peridotite obsidian

All are from particles “glued” together Chert Breccia Limestone

All these have been pushed down into earth and reheated gneiss hornfels

All rocks are classified by how they are formed (made). (Remember this!)

What are the three kinds of rock: Igneous: When lava or magma cools and hardens Sedimentary: When particles are “glued” together Metamorphic: When rocks are changed by heat and pressure in earth

Igneous rocks What are they? Why do they look different? From cooled magma (underground) or lava (above ground) Why do they look different? Cool at different rates Intrusive – cool inside Earth (slow cooling= big crystals) Extrusive – cool outside Earth’s interior (fast cooling = small or no crystals)

Which kind of igneous rock will be formed? https://www.youtube.com/watch?v=FL5Gq1GaxC0

More differences: Color of Igneous Rock Rocks high in silica are lighter in color Rocks low in silica are darker in color Silica- A chemical compound that makes most of the Earth's rocks. Silica occurs in different crystalline forms. It is also the main chemical compound in sand. Silica is used to make glass, concrete, and other materials.

Sedimentary rocks What are they? Why do they look different? Made of sediments cemented together Why do they look different? Made of different things Clastic – made of particles from erosion Chemical – made of dissolved materials Organic – made of living material

Which kind of sedimentary rock will be formed? https://www.youtube.com/watch?v=1Ou1bIDn1xE

Clastic Sedimentary rock is named according to chunk size Pebbles – conglomerate Sand – sandstone Mud – mudstone (may contain fossils) Shell particles – limestone

Metamorphic rock What are they? Why do they look different? Have been changed by heat and pressure underground Why do they look different? Foliated – layers form from pressure in one direction Non-foliated – no layers form – pressure comes from all directions

What kind of metamorphic rock is formed? https://www.youtube.com/watch?v=e15n7-zq0mA

Metamorphic Rock Some examples: Limestone → marble → Graphite (carbon)→ Diamond →

Check yourself: Which kind of rock?

Rock Cycle Processes Describe each of the following in your own words as we watch the animation on the following slide: Crystallization Weathering and erosion Transportation of sediments Deposition of sediments Compaction and cementation of sediments Uplifting Metamorphism Melting

The Rock Cycle! Animation! http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/es0602page02.cfm