1
1. Igneous Rocks
2
3
There are many kinds of rock in Earth’s crust
These rocks are made up of different minerals
4
Rocks can be grouped by the way they form throughout the
rock cycle
5
Igneous rocks form from melted, liquid rock
Vocabulary
Igneous rocks
Rock formed when hard liquid rock cools and hardens
6
This process may take place inside Earth
or on Earth’s surface
7
Inside Earth, magma cools so slowly that it may take a
thousand years for a rock to form
8
One of the most common kinds of igneous rocks is granite
Granite is made by magma cooling inside Earth
9
Granite is light colored with large crystals
It is made up mostly of the minerals quartz and feldspar
10
Granite is strong and does not break easily, even under
pressure
It is often used in buildings and bridges
11
Basalt is made when lava pours onto the ground or onto the
ocean floor
Because the lava cools quickly, the crystals in basalt are small
12
When lava erupts underwater it makes pillow-shaped lumps,
called pillow lava
13
Sometimes, lava cools so quickly that crystals never
have a chance to form
Pumice and obsidian are igneous rocks that do not have
crystals
14
Pumice is full of bubbles and is so light that it floats
15
Obsidian is a glassy, black rock
16
Video: How to Make Rock Candy