Quirks & Quarks

Earth has an ocean's worth of water locked deep inside

It's stored in mineral deposits up to 600 km below the surface.
Water exists much deeper in our planet that scientists once thought. It's held in minerals like Brucite. (Rob Levinsky)

It's well known that over two-thirds of the Earth's surface is covered with water, but the amount below the surface is less understood.  Hydrous minerals were thought to be able to store some of that deep Earth water to a certain depth before increasing pressure results in its decomposition.  But a new study by Dr. Mainak Mookerjee, an Assistant Professor of Earth, Ocean and Atmospheric Sciences at Florida State University has found that one mineral in particular - brucite - can store water much deeper than previously thought.  High-pressure experiments show that brucite remains thermodynamically stable at depths of 400 to 600 kilometres into the Earth's mantle.  This understanding helps support estimates that there may be at least a complete ocean worth of water stored inside our planet.   

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