High-Pressure Silicate Found in Earth’s Lower Mantle

A mineral known as a high pressure calcium silicate perovskite has been discovered for the first time. The discovery, named davemaoite after geophysicist Ho-kwang “Dave” Mao, is a naturally occurring mineral and was found 660 kilometers beneath Earth’s surface.

An article by the American Association for the Advancement of Science describes the discovery. “Davemaoite was named in honor of Ho-kwang (Dave) Mao – a prominent experimental high-pressure geophysicist – and confirmed as a new mineral by the International Mineralogical Association. According to Oliver Tschauner and colleagues, calcium silicate perovskite (CaSiO3) is among the most geochemically important minerals in the lower mantle, largely because it concentrates elements that are incompatible in the upper mantle, including rare-earth elements and radioactive isotopes that make an important contribution to the heat of Earth’s mantle.”

The rarity and scientific value of the discovery adds to the significance of the finding. The mineral has been theorized for decades, yet it had previously never been found. Specifically, no one had found a high pressure silicate from Earth’s lower mantle because of the difficulty of retaining its high pressure structure after being removed from pressure and heat. The only other time a high pressure phase silicate was found was inside a shocked meteorite.

The reason that davemaoite was able to keep its shape and form was because of the fact that it contained potassium, thorium, and uranium, which are all conducive to creating heat. Further research revealed that the mineral likely influences heat generation in the lower mantle of the Earth. The researchers came to this conclusion by analyzing the existence of compositional heterogeneity in the lower mantle, along with the general abundance of davemaoite in that layer of Earth. 

“The work by Tschauner et al. inspires hope in the discovery of other difficult high-pressure phases in nature, either through careful search in deep-origin diamonds or in highly shocked meteorites,” writes Yingwei Fei in a related Perspective. “Such direct sampling of the inaccessible lower mantle would fill our knowledge gap in chemical composition and heterogeneity of the entire mantle of our planet.”

The discovery of davemaoite creates reason for other high pressure silicates to be discovered, and with these discoveries comes the potential for new technology.


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