A xenolith is a piece of rock trapped in another type of rock.


6 - 12+


Earth Science, Geology, Geography, Physical Geography

NGS Resource Carousel Loading Logo
Loading ...
Powered by
Morgan Stanley

A xenolith is a piece of rock trapped in another type of rock.

Most of the time, a xenolith is a rock embedded in magma while the magma was cooling. Magma is the molten rock beneath Earth's crust that emerges as lava during a volcanic eruption. The rock that forms from cooled magma is called igneous rock. Xenoliths are different types of rock embedded in igneous rock.

Xenoliths are torn from deep cracks, or pipes, in Earth's surface. Magma rises to Earth's surface through these pipes between Earth's crust and mantle. As the molten material rises, it tears off bits and pieces of the magma pipe in which it is traveling. These bits and pieces, trapped in the magma but not melting into it, become xenoliths. Crystals that are torn from the sides of magma pipes are called xenocrysts.

As magma erupts or flows from Earth's surface, it is cooled by exposure to air or water. Lava cools fairly quickly, and various types of igneous rocks are formed. Xenoliths are usually visible. They have a different color and density than the surrounding igneous rock. Xenoliths can be as small as a grain of sand or as large as a football, and as long as several meters.

Xenoliths and xenocrysts are affected by temperature. A xenolith may lose its unique qualities if it melts into the surrounding magma. As it cools, the material may cease being a xenolith at all and become a metamorphic rock. Metamorphic rock is rock that has changed from one form (sedimentary or igneous) to another.

Xenoliths and xenocrysts are often identified by the names of the two rock types involved. A peridotite xenolith in a basaltic lava flow, for instance, means a chunk of the rock peridotite is embedded in basalt rock. The peridotite is usually yellow and dense, while the basalt is usually grey and light.

Xenoliths and xenocrysts provide valuable information about the geology of Earth's mantle. Scientists study the chemical properties of xenoliths to understand the depth at which they were formed. Many xenocrysts were created hundreds of kilometers within Earth, far below the deepest mines and wells. The information about the condition of the mantle at these depths would be impossible to understand without xenoliths and xenocrysts. Some of the features studied by geologists are temperature, pressure, construction, and movement within the Earth's surface.

Xenoliths can be a piece of rock trapped in a piece of sedimentary rock, but this is rare. Xenoliths have also been found in meteorites, or rocks from outer space that have crashed into Earth. The xenoliths in meteorites were formed from collisions with other objects outside the Earth's atmosphere.

Fast Fact

Xenocrysts are a Girl's Best Friend
Diamonds are formed in Earth's upper mantle. A type of igneous rock called kimberlite is known for carrying xenocrysts of diamonds to the surface, where they can be mined. Kimberlite was named after the rich Kimberley mine in South Africa, where a diamond rush began in 1871.

Media Credits

The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Kim Rutledge
Melissa McDaniel
Santani Teng
Hilary Hall
Tara Ramroop
Erin Sprout
Jeff Hunt
Diane Boudreau
Hilary Costa
Mary Crooks, National Geographic Society
Tim Gunther
Jeannie Evers, Emdash Editing, Emdash Editing
Kara West
Educator Reviewer
Nancy Wynne
National Geographic Society
Last Updated

April 24, 2024

For information on user permissions, please read our Terms of Service. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. They will best know the preferred format. When you reach out to them, you will need the page title, URL, and the date you accessed the resource.


If a media asset is downloadable, a download button appears in the corner of the media viewer. If no button appears, you cannot download or save the media.


Text on this page is printable and can be used according to our Terms of Service.


Any interactives on this page can only be played while you are visiting our website. You cannot download interactives.

Related Resources