By: Ella Breitenfeldt

What are Igneous rocks?Igneous rocks form when magma or lava

cools.Some of the most common rocks are Igneous.Basalt, a type of Igneous rock, covers most of

the ocean floor.Over 700 Igneous rocks have been named.

Intrusive or Extrusive?Intrusive rock forms under earth’s crust after

years of magma slowly cooling.Extrusive rock forms when lava cools above

earth’s surface.Intrusive rock has time to form crystals; you can

see the mineral grains with the bare eye.Extrusive rock cools instantly and has no time to

form large crystals; you’d need a microscope to see the mineral grains.

Diorite (intrusive)

Intrusive or Extrusive continuedIntrusive rock is also called plutonic rock.Extrusive rock is also called volcanic rock.Intrusive rocks can take up to 100 years to

form completely.

ClassificationYou can classify rocks by the minerals they

have within.An Igneous rock can either be basaltic,

granitic, or andesitic.Basaltic rocks are dense, heavy, dark-

colored rocks.Granitic rocks are light-colored and have

less density then balsaltic.

Fun FactsMost Igneous rocks are plutonic.Igneous rocks are the oldest type of rock.Granite, a type of Igneous rock, was used to

build the Empire State Building.Basalt covers most of the ocean floor.95% of the top ten miles of the Earth’s crust

is Igneous rock.Only Igneous rocks are formed when lava or

magma cools.

Fun activity for home Using this project, you can understand how

Igneous rocks are formed.Materials: -half of a chocolate bar -marshmallow -cooking pot -wax paper -plate

Activity continued Do It!1. Melt the chocolate bar and the

marshmallow in the pot.2.When heated, pour the mixture onto the wax

paper, on the plate.3.Put the mixture into the fridge and check the

next day.

How did the rock change shape-wise?What do you think would’ve happened if you

tilted the plate?

Thank you!This slide show was made by Ella

Breitenfeldt.

I hope you had fun!