1. Rocks!
Pages in Science Plus

2. Introduction to Rocks Rocks can be classified into three groups:
Igneous
Sedimentary
Metamorphic
Rock cycle- constant cycle of old rocks turning into new rocks.

4. Igneous Rocks Igneous rocks- made from hardened lava or magma.
As they are formed crystals develop within the rock.
There are two types of igneous rocks.

5. Igneous Rocks: Intrusive
Intrusive rocks (plutonic rocks)- made from hardened magma (Below the earth’s surface.)
These rocks may be coarse or fine grained.
Typically have large crystals.
Examples include:
Granite
Syenite
Above: Granite
Right: Synite

6. Igneous Rock: Extrusive
Extrusive Rock (Volcanic rock) - made from hardened lava. (Above the earth’s surface)
Due to rapid cooling these rocks are usually fine grained or have tiny air bubbles.
Usually small crystals if any.
Examples include:
Pumice
Basalt
Pumice
Basalt

7. Sedimentary Rock
Sedimentary Rock- made from sediments, or pieces, of other rocks being pressed together.
You can see the small segments of the other rocks within the larger rock.
Lithification -the process by which rocks stick together because of pressure.
There are the three types of sedimentary rock.
The "Finger of God", also known as Mukorob, a rock pillar in southern Namibia, photographed in A 34 meter column of sandstone rests on softer mudstone, which has eroded away to a narrow neck. The pillar eventually blew down in a storm on 4 December 1988.

8. Sedimentary Rock: Clastic
Clastic rocks- made of broken pieces of weathered rock that have been pressed together.
Examples include:
Conglomerate
Sandstone

9. Sedimentary Rock: Chemical
Chemical rocks - made from minerals that have dissolved in water, the water has evaporated, and minerals have been left behind forming crystals.
Examples include:
Travertine

10. Sedimentary Rock: Organic
Organic rock - formed from once living organisms that have been pressed together over a long period of time.
Examples include:
Chalk
Limestone

11. Metamorphic Rock
Metamorphic Rock- formed deep within the earth from a combination of heat and pressure.
There are two types of metamorphic rock.

12. Metamorphic Rock: Foliated
Foliated rocks - formed with bands or zones running throughout the rock.
Examples include:
Gneiss
Slate

13. Metamorphic Rock: Nonfoliated
Nonfoliated rocks do not have bands or zones.
Examples include:
Quartzite
Coal
Diamonds