Scientists Say: Inclusion

For those who study rocks, this is a material trapped inside a mineral as it forms


The bubble inside this piece of quartz is a type of inclusion. Inside the bubble is methane gas.

LucasFassari/Wikimedia Commons (CC BY-SA 4.0)

Inclusion (noun, “In-CLUE-shun”)

This word has a special meaning in mineralogy — or the study of minerals. To mineralogists, an inclusion is any material trapped inside a mineral as it forms. That material could be a rock trapped inside another rock. It can be a bug or a feather stuck in a glob of amber. It could be a bubble of gas trapped inside a gem. Inclusions can reveal important insights about the ancient world. For example, an insect trapped in amber can tell scientists a lot about what life was like when the amber formed — all the way down to a bug’s last meal. Climate scientists are interested in inclusions in other substances as well. They look for inclusions of gas bubbles in ancient ice cores or salts. Those bubbles can tell scientists what the Earth was like long ago.

In a sentence

Tiny inclusions in ancient rock salt helped scientists figure out how much oxygen filled Earth’s air 815 million years ago. 

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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