A blue flaw in a gem-quality diamond from Africa is a tiny fragment of Earth's deep interior, and it suggests our planet's mantle contains oceans' worth of water.

The flaw appears to be a deep blue center surrounded by a white haze. The mineral ringwoodite can be found at the boundary between the upper and lower mantle. This is the second time scientists have found this mineral in a chunk of crystal from this area, and the sample is the only one of its kind currently known to science. An attempt was made to analyze its chemistry.

It's more difficult to find a ringwoodite inclusion.


This very deep zone of Earth is soggy with a lot of water locked up inside the minerals. The water is bound to the minerals and doesn't flow like an ocean, but it does play an important role in how the mantle will melt. This affects big- picture geology, such as plate tectonics. Water could be a factor in the development of areas of mantle upwelling, which are hot spots for volcanic activity.

The discovery of the diamond-encased mantle was made by a mineral physicist at the Gemological Institute of America. She was studying rare diamonds. They cloud a diamond's sparkle because they are not desirable for jewelry. They are interesting to scientists because they trap bits of the environment where the diamond began.

Mineral inclusion containing assemblage of ringwoodite, enstatite and ferropericlase.
Mineral inclusion containing assemblage of ringwoodite, enstatite and ferropericlase. Field view is 0.91 mm. Credit: Nathan D. Renfro and Tingting Gu at GIA Carlsbad. Credit: Nathan D. Renfro and Tingting Gu

Diamonds form between 150 to 200 km below the surface. A few come from a lot deeper. Gu and her colleagues reported on Monday that the new sample was very accommodating when it came to figuring out how deep it was. It can only form at high pressures. Sometimes it is seen trapped in meteorites that have undergone major trauma. Ringwoodite can be found at the pressures of 660 km. It is said that the ringwoodite sample found in a diamond formed within 135 km of that depth. The two minerals found in the new inclusion, ferropericlase and enstatite, can only be found 660 km away.

It is an important depth because it is the boundary between the mantle layers and it is where the earthquakes occur. As the mineral undergoes changes at this boundary, it is likely to release a lot of water. The change in minerals could explain why the waves travel differently through this region.

The ringwoodite inclusion has a small amount of water bound to the molecule that makes up the mineral. There has been little proof that the mantle can hold large amounts of water. The first hint was the ringwoodite discovery, but this second sample is more convincing. Water can easily surpass water on the planet's surface if the mineral is largely waterlogged in the mantle transition zone. She says that if you only have one sample, it can be a local hydrous region. It is likely to be common.


Oliver Tschauner is a mineralogist at the University of Nevada, Las Vegas who was part of a team that discovered a high-pressure form of water ice in ultra deep diamonds. As the plates are pushed into the mantle, they carry water with them, but they don't know how deep the water can go. It is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 is1-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-65561-6556 Understanding the way water cycles between Earth's depths and surface could help explain how it became a hydrated planet over 4.5 billion years ago.

Researchers will need to analyze trace elements to learn more. More ringwoodite can be found in diamonds in the future. Gu says that it was a lucky break. She advises against saying no if someone proposes with a diamond.