Rare diamonds suggest water lurks much deeper in Earth's interior than scientists thought

Water can penetrate deeper into Earth's interior than previously thought, according to a rare diamond.

Water can be found in minerals more than 200 miles underground, including in the upper mantle, a semi-flexible layer on top of the planet. As the upper mantle transitions into the hotter, denser lower mantle, scientists think minerals can hold less water.

In a new study published in the journal Nature Geoscience, researchers found that a diamond contained tiny bits of other minerals that may have held more water than was previously thought. The results suggest that there may be more water in the Earth than scientists thought, which could affect our understanding of the deep water cycle.

There are giant blobs in Earth's mantle that may be driving a diamond factory.

The lead study author was a researcher at the Gemological Institute of America in New York City at the time of the study.

A rare type of diamond from the Karowe mine in Botswana that forms deep underground and is often in the Earth for a long time was examined by Gu and her colleagues. They used a variety of nondestructive methods to study the diamond, including the use of a laser to reveal some of a material's physical properties.

The researchers found a mineral called ringwoodite, which has the same chemical composition as olivine, the primary material of the upper mantle, but forms under such intense temperature and pressure. The transition zone between the upper and lower mantle is where Ringwoodite can be found, and it can contain more water than other minerals.

The minerals around this ringwoodite were similar to those found in the lower mantle. The researchers estimated the minerals' depth to be around 410 miles (660 km) below the surface because the diamond preserved their properties as they appeared in the deep Earth. The analysis showed that the ringwoodite was breaking down into a more typical lower minerals mantle in a hydrous environment, suggesting that water could get into the lower mantle.

The authors noted that the combination of materials in this inclusion is unique and that there are some forms of minerals from the lower mantle. The study authors said it was not clear if the minerals pointed to the presence of water in the mantle. Diamonds are one of the few sources of minerals from the Earth's mantle.

Gu said the results could have implications for understanding the deep water cycle.

It would take more time for water to renew itself if it were stored deep underground.

Modelling of plate tectonics might be affected by the findings. Gu hopes that scientists will be able to incorporate the study's findings into models of how water in the mantle might affect processes. The current causes hotter parts to rise and shift the Earth's plates over millions of years.

Gu said that diamonds can provide valuable scientific information if they are not blemished.

She said you never know what a diamond might contain.

The year when scientists first detected ringwoodite in the minerals mantle is incorrect.

It was originally published on Live Science