Igneous rocks

Igneous rocks can be made from magma or lava.

Igneous rock can form from magma under the Earth’s surface. Magma is very hot molten rock that can harden when it cools underground, forming igneous rock.

Igneous rocks can also be formed on the surface of the Earth. When magma reaches the surface we call it lava. When the lava cools it hardens and becomes an igneous rock.

Follow the video and add the pictures and facts below to your rock cycle worksheet.

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Describe a Igneous Rock

There are lots of different types of igneous rock and what they look like depends where they formed.

Explore some of the igneous rocks in the GeoBus collection below. Move your mouse over the top of the first image to find out more about that rock.

Obsidian

This piece of obsidian is from Anatolia in Turkey. Obsidian forms when molten rock cools very quickly, forming a volcanic glass instead of a rock. It is usually smooth, shiny and black like this piece in our collection. Obsidian can also be broken to have very sharp edges and was actually used in the Stone Age to make spear heads.

Basalt

Basalt is a very common igneous rock and is mostly formed by cooling lava, but can also be formed from magma cooling inside the Earth. Our basalt has lots of little holes (pitted) which are formed by gases being trapped as bubbles inside the lava as it cooled into rock.

Pumice

This pumice is from the Lipari Islands in Italy. Pumice is very light because it is full of so many small holes (pitted). It can float in water and even form giant rafts across oceans. Typically formed in very explosive volcanic eruptions, the holes inside are formed by bubbles of gas.

Famous Rocks: Hawaii

The Hawaiian Islands are formed of eight major islands, the volcanoes are mainly made of the igneous rock called basalt. The highest point on this island is the Mauna Kea volcano, at 4207 m.

Explore the island of Hawaii in the 3D model below.

Hawaii, USA by CMPLab on Sketchfab

Proceed to Part 4: Metamorphic Rocks