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Igneous Rock Definition

Igneous rock forms from cooled magma or lava. For example, lava cools quickly above the surface to form igneous rock.

View Lesson on Rocks & Minerals (Including Rock Cycle)
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Rocks & Minerals (Including Rock Cycle)

Fun Facts

  • Obsidian forms when lava cools down fast.
  • Igneous rocks form by liquid magma cooling near Earth's surface.
  • Igneous rock breaks apart over thousands of years to form sediment.

Why Do We Need To Know About Igneous Rock

Learning about igneous rocks helps us see how they’re used in many ways and why they’re important for different jobs. For example, gabbro is used to make roads and granite is used in buildings, showing how these rocks help in making things we use every day. Also, people a long time ago used obsidian, another type of igneous rock, to make sharp tools and weapons.

These rocks are also important in new technology and exploring space. Quartz, a mineral from igneous rocks, is used in electronics because it can keep time when powered. Studying igneous rocks on Earth and other planets like Mars shows how geology, the study of rocks, is not just about the past but also about finding new things in space.

Frequently Asked Questions

How are rocks and minerals different?
Minerals are solid, naturally formed substances that always have the same composition and the same properties. Rocks are made of minerals.
How do crystals form?
Hot water dissolves minerals. When the water evaporates, it leaves behind the dissolved minerals in a crystal structure.
Describe three ways rocks make our lives easier.
Gabbro is a type of rock used to make roads; granite is used in building materials; coal is used to generate electricity; and shale is used to make bricks.
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