Contents
Key Stage 3
Meaning
An igneous rock is a rock formed from magma or lava.
About Igneous Rocks
- When magma or lava freezes it is called an igneous rock.
- When the magma is trapped underground it freezes slowly and this makes very large cyrstals in the rock. This is called intrustive rock.
- When the lava comes out of the volcano it cools down and freezes quickly making small crystals. This is called extrusive rock.
- Igneous rocks have large interlocking grains.
Examples
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| Granite is an igneous rock with large interlocking grains. | Gabbro is an intrusive igneous rock. | Diorite cools very slowly underground so it has large crystals. |
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| Basalt forms from lava so it is an extrusive igneous rock. | Obsidian is an igneous rock that cools so quickly that crystals don't have any time to form at all. | Pumice bursts out of Volcanoes and gives of gases that make bubbles inside making it look like a sponge. |