Rock Types

Igneous, Sedimentary, Metamorphic

Igneous rocks make up 95% of the rocks of the crust of Earth. They are also some of the oldest rocks that are found at the surface of Earth.

Igneous rocks form from molten rock which is either ejected at the surface of Earth or cools off underground. When volcanoes erupt, they can eject molten rock.

Extrusive Igneous Rock• Extrusive means to stick out. Extrusive

rocks form when they cool at the Earth’s surface. Because of their rapid cooling, they have smaller crystals.

Extrusive rocks that cool quickly have very small crystals.

Obsidian is a good example of a very quickly cooled extrusive igneous rock. It appears glass-like.

Sometimes when an extrusive rock is cooled very quickly and has lots of

air pockets we get pumice or scoria.

Pumice

Scoria

Intrusive rock cools under the surface. It has more time to

cool and forms larger crystals.

GraniteDiorite

Quartz

Sedimentary rocks are the result of the processes of weathering and

erosion which are continually breaking down and rearranging them. Small rocks, fragments and organic

remains that have been moved by water, wind or other agents of erosion are called

sediment. Over a period of time, sediment is cemented together.

Sandstone

Sedimentary rocks can be formed from metamorphic, igneous or other sedimentary

rocks that have been broken down by weathering. In nature sedimentary rocks are usually found in layers with the oldest

layer on the bottom.

Three types of Sedimentary Rocks• Clastic: made of broken pieces of other

rocks that are squeezed and cemented together. Sandstone

Shale

Breccia

Organic Sedimentary Rocks• Remains of plants and animals.

Limestone

Coal

Chemical Sedimentary Rocks• Dissolved minerals that crystallize by

precipitation or evaporation.

HaliteGypsum

Limestone

Metamorphic Rock

METAMORPHIC ROCK

Has this ever happened to you?

You take a peanut butter and jelly sandwich to school. You check your backpack at lunch

and find that your books have been sitting on the sandwich all day! The heat of the day and

pressure of the books have mushed the sandwich into a completely different shape.

Your lunch has experienced what rocks experience deep in the interior of Earth, the

process of metamorphism.

Rocks that have changed shape or composition due to intense heat and pressure are called metamorphic

rocks. • Metamorphic rocks are created from

sedimentary, igneous or other metamorphic rocks.

• They are formed deep inside the earth.

• Heat and pressure from the rock above AND below flatten and bend the rock.

HEAT & PRESSURE

Foliated or Non-foliated

SlatePhyllite

Schist

Gneiss

Quartzite

Marble

Shale + Heat & Pressure = Slate

Basalt + Heat & Pressure = Schist

Granite + Heat & Pressure = Gneiss

Limestone + Heat & Pressure = Marble

Sandstone + Heat & Pressure = Quartzite

Remember!

• Igneous rocks are formed by cooling of magma, either above or below the Earth’s surface.

• Sedimentary rocks are formed from broken pieces of other rocks (sediment) of all sizes.

• Metamorphic rocks are other rocks that are changed through heat and pressure.

What kind of rock is pumice?

Igneous? Sedimentary? Metamorphic?

Pumice is an igneous rock!

What kind of rock is quartzite?

Igneous? Sedimentary? Metamorphic?

Quartzite is a metamorphic rock!

What kind of rock is coal?

Igneous? Sedimentary? Metamorphic?

Coal is a sedimentary rock!

•Is coal a mineral????

What kind of rock is obsidian?

Igneous? Sedimentary? Metamorphic?

Obsidian is an igneous rock!

What kind of rock is halite (salt)?

Igneous? Sedimentary? Metamorphic?

Halite is a sedimentary rock!

What kind of rock is sandstone?

Igneous? Sedimentary? Metamorphic?

Sandstone is a sedimentary rock!

What kind of rock is limestone?

Igneous? Sedimentary? Metamorphic?

Limestone is a sedimentary rock!

What kind of rock is basalt?

Igneous? Sedimentary? Metamorphic?

Basalt is an igneous rock!

What kind of rock is gneiss?

Igneous? Sedimentary? Metamorphic?

Gneiss is a metamorphic rock!

Da Rock Cycle!