Imagine digging a hole straight through the Earth. You would pass through the thin skin of the crust, descend into a churning rocky layer called the mantle, and eventually reach the molten iron core at the centre. But somewhere between 660 and 2,900 kilometres below your feet, in a dark and crushing region called the lower mantle, there is a mineral that scientists have been arguing about for decades. Does it actually exist down there? Or does it dissolve away under the unimaginable heat and pressure of Earth's deep interior?
The answer, according to a landmark new study, is a resounding yes. And that single confirmation carries far-reaching consequences. It helps explain mysterious seismic tremors deep inside our planet and sheds light on the origin of volcanic islands scattered across the ocean floor.
Meet Davemaoite: Earth's Deep Hidden Mineral
The mineral at the centre of this story is called davemaoite, a form of calcium silicate (CaSiO₃) that belongs to a class of crystal structures known as perovskites. It was only formally recognized and named in 2021, after a tiny fragment of it was discovered trapped inside a diamond that had been blasted upward from the deep mantle by a volcanic eruption long ago.
Think of davemaoite as one of the most geologically significant minerals you have probably never heard of. Scientists believe it shares the lower mantle alongside another mineral called bridgmanite, the single most abundant mineral on our planet, making up roughly 38 percent of Earth's total volume. These two minerals, side by side in the dark depths, may shape everything from the movement of tectonic plates to the heat balance of Earth's core.
But there was a problem. Some scientists argued that davemaoite simply could not survive down there. Their reasoning was that bridgmanite might absorb calcium so efficiently at high temperatures that davemaoite would dissolve entirely into it, vanishing without a trace. If true, one of the most important minerals in Earth's interior would essentially cease to exist.
"Davemaoite has been stable in Earth's lower mantle since its formation and it is expected to persist there throughout the entirety of geological time."
Recreating the Deep Earth in a Laboratory
To settle this debate, researchers used an extraordinarily powerful device called an ultrahigh pressure multi anvil press. Picture a machine that can squeeze a tiny sample of rock between massive anvils made of the hardest known materials, generating pressures equivalent to those found 660 to 1,500 kilometres beneath Earth's surface, all while simultaneously heating the sample to temperatures between 2,300 and 2,700 Kelvin. That is hotter than the surface of some stars.
The experiments were conducted at pressures ranging from 27 to 50 gigapascals, which is 27,000 to 50,000 times the atmospheric pressure you experience standing outside on a clear day. The researchers tested five different starting materials with compositions designed to mimic various regions of the actual lower mantle, including samples that contained iron and aluminium in addition to calcium and magnesium.
After each experimental run, which lasted 24 hours to ensure the minerals had time to reach true chemical equilibrium, the samples were analyzed using some of the most powerful imaging tools available. Scanning transmission electron microscopy allowed the team to map the chemical composition of each recovered sample at a resolution of just 10 to 15 nanometres per pixel. To put that in perspective, a human hair is roughly 80,000 nanometres wide.
The Result: Davemaoite Simply Cannot Be Absorbed
The findings were clear and conclusive. Across every experimental condition tested, regardless of temperature, pressure, or the presence of iron and aluminium, bridgmanite simply did not absorb enough calcium to make davemaoite disappear. The calcium content in bridgmanite, technically called χCa, never exceeded 0.025 per formula unit even at the highest temperatures tested. To dissolve all the davemaoite present in a typical mantle composition, that value would need to reach at least 0.08, which is more than three times higher than what was observed.
Most tellingly, when the researchers examined samples that started with a relatively low calcium content of just 4 percent, they could still see two distinct perovskite minerals sitting side by side under the microscope at 40 gigapascals and 2,600 Kelvin. Bridgmanite and davemaoite were coexisting unmistakably, each holding their own.
The team also tackled a potential objection: what if the results were simply an artefact of the experiment, where the minerals had not truly reached equilibrium? To rule this out, they ran a zero time experiment, essentially quenching the sample the instant it reached the target temperature, and compared the grain sizes and compositions to samples annealed for a full 24 hours. The comparison confirmed that chemical equilibrium had indeed been achieved and that calcium diffuses fast enough under these conditions to produce reliable and meaningful results.
Why This Matters: A Mineral That Quietly Shapes Our World
You might be wondering why anyone should care about a mineral that exists hundreds of kilometres underground in a place no human will ever visit. The answer is that davemaoite is not just a geological curiosity. It is a key player in some of the most dramatic and consequential processes happening on our planet right now.
For starters, davemaoite is a chemical sponge. It is remarkably good at absorbing what geochemists call incompatible elements, which include radioactive materials like uranium and thorium as well as rare earth elements. These are substances that do not fit comfortably into most mineral structures and tend to concentrate wherever they can find a home. In the lower mantle, davemaoite acts as their principal reservoir.
The radioactive elements stored in davemaoite generate heat as they decay over billions of years. This heat, locked deep in the mantle near the core mantle boundary, may have helped keep Earth's core hot for an extraordinarily long time, possibly even delaying the moment when the inner core first began to solidify. That solidification is what drives Earth's magnetic field, the invisible shield that protects our planet from harmful solar radiation. In other words, davemaoite may have played a quiet but critical role in making Earth habitable for life.
The Mystery of the Giant Seismic Blobs
Deep inside Earth, seismologists have long known about two enormous structures sitting at the base of the mantle, one beneath Africa and one beneath the Pacific Ocean. These structures, formally called large low shear wave velocity provinces or LLSVPs, are colossal anomalies each roughly the size of a continent, where seismic waves travel noticeably slower than in the surrounding rock. Scientists have long suspected these structures are chemically distinct from the rest of the mantle, but their exact composition has remained a stubborn mystery.
The new study offers a compelling explanation. Using thermodynamic models, the researchers calculated that davemaoite enriched material, meaning clumps of rock with an unusually high concentration of this calcium rich mineral, would naturally accumulate at the core mantle boundary over geological time. As ancient tectonic plates sank into the mantle through a process called subduction, they may have swept up and concentrated a layer of davemaoite that originally crystallized during the solidification of a global magma ocean that covered the early Earth billions of years ago.
The calculations show that a region enriched with just 8 to 20 percent davemaoite would produce exactly the kind of seismic slowdown observed in the LLSVPs. This makes davemaoite the strongest candidate yet for explaining these giant mysterious structures at the base of our planet and suggests the African and Pacific mantle blobs may carry chemical memories of Earth's earliest history.
A Window Into Ocean Island Volcanoes
There is another fascinating thread to pull on here. Ocean island volcanoes like those that built Hawaii, the Canary Islands, and Iceland erupt lavas with a chemical fingerprint that is distinctly different from the basalts produced at mid ocean ridges. For decades, geochemists have puzzled over this difference, suspecting that these volcanoes must be tapping into some ancient and chemically enriched reservoir buried deep in the mantle.
Davemaoite enriched domains at the core mantle boundary fit this role perfectly. With their cargo of uranium, thorium, and rare earth elements, these pockets of davemaoite rich rock could be the deep source that gives some ocean island basalts their distinctive chemical character. When a mantle plume, which is a column of unusually hot rock rising from the deep Earth, passes through one of these enriched domains, it would carry that chemical signature all the way up to the surface, eventually erupting as a chemically distinct volcanic island in the middle of the ocean.
Stable Since the Very Beginning
Perhaps the most remarkable conclusion of the study is its sweep across geological time. The thermodynamic extrapolation of the experimental data all the way to conditions at the core mantle boundary, at pressures around 135 gigapascals and temperatures approaching 4,000 Kelvin, shows that the calcium content in bridgmanite remains far too low to dissolve davemaoite even at these extreme depths.
The models also show that even if the ancient mantle was significantly hotter than it is today, as it would have been in the first billion years of Earth's history, davemaoite would still have survived. The temperature required to fully dissolve davemaoite into bridgmanite would actually exceed the melting point of the mantle itself. In other words, you would have to melt the entire mantle before davemaoite would disappear.
This means davemaoite has been a permanent resident of Earth's lower mantle since the planet's formation roughly 4.5 billion years ago. It has been there through every mass extinction, every supercontinent cycle, every ice age. A silent and invisible mineral sitting in the darkness far beneath our feet, quietly influencing the world above.
Rewriting Our Picture of Earth's Interior
This research resolves what had been one of the most persistent debates in deep Earth science. It confirms that the lower mantle is not a simple and uniform layer of bridgmanite but a complex mineralogical landscape in which davemaoite plays a crucial and enduring role.
For geophysicists studying the slow churning of Earth's mantle over millions of years, knowing that davemaoite is real and stable changes the picture significantly. It affects models of how heat moves through the planet, how subducted slabs of oceanic crust accumulate over time, and how chemical diversity is preserved across billions of years of geological history.
For anyone who has ever wondered what lies beneath the ground we walk on, this study is a reminder that our planet is far more intricate and surprising than it might appear from the surface. Earth is not a simple ball of rock. It is a dynamic and layered system still full of secrets, and davemaoite is one of the most remarkable ones we have now confirmed.
Publication Details: Year of publication: 2025 Journal: Nature Geoscience Publisher: Springer Nature Volume / Pages: Volume 18, April 2025, pp. 365–369 DOI: https://doi.org/10.1038/s41561-025-01657-9
Credit & Disclaimer: This article is based on the peer reviewed research paper. All scientific facts, findings, and conclusions presented here are drawn directly from the original study and remain unchanged. This popular science article is intended purely for general educational purposes. Readers are strongly encouraged to consult the full research article for complete experimental data, methodology, and detailed scientific analysis.
