Harry Baker
Within a diamond hauled from deep beneath Earth's surface, scientists have discovered the first example of a never-before-seen mineral.
© Provided by Live Science Researchers discovered the mineral davemaoite
inside a diamond that was formed in Earth's mantle.
Named davemaoite after prominent geophysicist Ho-kwang (Dave) Mao, the mineral is the first example of a high-pressure calcium silicate perovskite (CaSiO3) found on Earth. Another form of CaSiO3, known as wollastonite, is commonly found across the globe, but davemaoite has a crystalline structure that forms only under high pressure and high temperatures in Earth's mantle, the mainly solid layer of Earth trapped between the outer core and the crust.
Davemaoite has long been expected to be an abundant and geochemically important mineral in Earth's mantle. But scientists have never found any direct evidence of its existence because it breaks down into other minerals when it moves toward the surface and pressure decreases. However, analysis of a diamond from Botswana, which formed in the mantle around 410 miles (660 kilometers) below Earth's surface, has revealed a sample of intact davemaoite trapped inside. As a result, the International Mineralogical Association has now confirmed davemaoite as a new mineral.
"The discovery of davemaoite came as a surprise," lead author Oliver Tschauner, a mineralogist at the University of Nevada, Las Vegas, told Live Science.
Tschauner and his colleagues uncovered the davemaoite sample with a technique known as synchrotron X-ray diffraction, which focuses a high-energy beam of X-rays on certain spots within the diamond with microscopic precision. By measuring the angle and intensity of the returning light, researchers can decipher what's inside, Tschauner said. The sample of davemaoite within the diamond was just a few micrometers (millionths of a meter) in size, so less-powerful sampling techniques would have missed it, he added.
Davemaoite is believed to play an important geochemical role in Earth's mantle. Scientists theorize that the mineral may also contain other trace elements, including uranium and thorium, which release heat via radioactive decay. Therefore, davemaoite may help to generate a substantial amount of heat in the mantle, Tschauner said.
In a 2014 study published in the journal Science, researchers described another theoretical high-pressure mineral from the mantle, known as bridgmanite. However, the sample of bridgmanite did not originate from the mantle but rather inside a meteorite. The discovery of davemaoite shows that diamonds can form farther down in the mantle than previously thought, and it suggests that they might be the best place to look for more new minerals from the mantle, Tschauner said.
"The work by Tschauner et al. inspires hope in the discovery of other difficult high-pressure phases in nature," Yingwei Fe, a geophysicist at the Carnegie Institution for Science in Washington, D.C., who was not involved in the study, said in a related Science article. "Such direct sampling of the inaccessible lower mantle would fill our knowledge gap in chemical composition of the entire mantle of our planet."
The study was published online Nov. 11 in the journal Science.
Originally published on Live Science.
Named davemaoite after prominent geophysicist Ho-kwang (Dave) Mao, the mineral is the first example of a high-pressure calcium silicate perovskite (CaSiO3) found on Earth. Another form of CaSiO3, known as wollastonite, is commonly found across the globe, but davemaoite has a crystalline structure that forms only under high pressure and high temperatures in Earth's mantle, the mainly solid layer of Earth trapped between the outer core and the crust.
Davemaoite has long been expected to be an abundant and geochemically important mineral in Earth's mantle. But scientists have never found any direct evidence of its existence because it breaks down into other minerals when it moves toward the surface and pressure decreases. However, analysis of a diamond from Botswana, which formed in the mantle around 410 miles (660 kilometers) below Earth's surface, has revealed a sample of intact davemaoite trapped inside. As a result, the International Mineralogical Association has now confirmed davemaoite as a new mineral.
"The discovery of davemaoite came as a surprise," lead author Oliver Tschauner, a mineralogist at the University of Nevada, Las Vegas, told Live Science.
Tschauner and his colleagues uncovered the davemaoite sample with a technique known as synchrotron X-ray diffraction, which focuses a high-energy beam of X-rays on certain spots within the diamond with microscopic precision. By measuring the angle and intensity of the returning light, researchers can decipher what's inside, Tschauner said. The sample of davemaoite within the diamond was just a few micrometers (millionths of a meter) in size, so less-powerful sampling techniques would have missed it, he added.
Davemaoite is believed to play an important geochemical role in Earth's mantle. Scientists theorize that the mineral may also contain other trace elements, including uranium and thorium, which release heat via radioactive decay. Therefore, davemaoite may help to generate a substantial amount of heat in the mantle, Tschauner said.
In a 2014 study published in the journal Science, researchers described another theoretical high-pressure mineral from the mantle, known as bridgmanite. However, the sample of bridgmanite did not originate from the mantle but rather inside a meteorite. The discovery of davemaoite shows that diamonds can form farther down in the mantle than previously thought, and it suggests that they might be the best place to look for more new minerals from the mantle, Tschauner said.
"The work by Tschauner et al. inspires hope in the discovery of other difficult high-pressure phases in nature," Yingwei Fe, a geophysicist at the Carnegie Institution for Science in Washington, D.C., who was not involved in the study, said in a related Science article. "Such direct sampling of the inaccessible lower mantle would fill our knowledge gap in chemical composition of the entire mantle of our planet."
The study was published online Nov. 11 in the journal Science.
Originally published on Live Science.
Introducing Davemaoite: A Groundbreaking Mineral Discovery Named After Trailblazing Carnegie Geophysicist
Friday, November 12, 2021
Washington, DC—The first-ever silicate mineral recovered from the Earth’s lower mantle has been named after emeritus Carnegie scientist Ho-kwang “Dave” Mao, an experimental geophysicist whose work redefined our understanding of how materials behave under the extreme pressure and temperature conditions found inside Earth and other planets.
A team led by the University of Nevada Las Vegas’ Oliver Tschauner reported the discovery in Science this week and Carnegie’s Yingwei Fei wrote an accompanying essay in the same issue, contextualizing the importance of the work and the significance of the chosen name—davemaoite.
In 1976 Mao and colleagues were the first to bring materials to a million times atmospheric pressure, doubling the previous pressure limit. This momentous breakthrough transformed our understanding of the chemistry of Earth’s interior and behavior of materials under extreme pressure. Over a career spanning five decades he continually redefined the boundaries of pressure at which materials could be probed, and his discoveries had implications for understanding the chemistry and physics occurring deep below Earth’s surface, our planet’s evolutionary history, the interior dynamics of distant worlds, and materials science.
“This honor is a fitting tribute given the profound impact Dave’s work has had throughout the geosciences,” said Earth and Planets Laboratory Director Richard Carlson. “His contributions have shaped our understanding of our world and now a piece of the world will forever bear his name.”
Many materials that form under extreme pressures cannot retain their structures when brought to ambient conditions, which is what makes this discovery so exciting. Davemaoite, which was discovered encased inside a super-deep diamond, is only the second high-pressure mantle silicate ever seen on Earth’s surface. The other, named after Nobel laureate Percy Bridgman, was found inside a meteorite.
“The two form an exclusive club as the only lower-mantle silicate minerals confirmed in nature.” Fei said.
Scientific Area:
Earth & Planetary Science
Reference to Person:
Yingwei Fei
Reference to Department:
Earth and Planets Laboratory
News Topic:
Earth/Planetary Science
Friday, November 12, 2021
Washington, DC—The first-ever silicate mineral recovered from the Earth’s lower mantle has been named after emeritus Carnegie scientist Ho-kwang “Dave” Mao, an experimental geophysicist whose work redefined our understanding of how materials behave under the extreme pressure and temperature conditions found inside Earth and other planets.
A team led by the University of Nevada Las Vegas’ Oliver Tschauner reported the discovery in Science this week and Carnegie’s Yingwei Fei wrote an accompanying essay in the same issue, contextualizing the importance of the work and the significance of the chosen name—davemaoite.
In 1976 Mao and colleagues were the first to bring materials to a million times atmospheric pressure, doubling the previous pressure limit. This momentous breakthrough transformed our understanding of the chemistry of Earth’s interior and behavior of materials under extreme pressure. Over a career spanning five decades he continually redefined the boundaries of pressure at which materials could be probed, and his discoveries had implications for understanding the chemistry and physics occurring deep below Earth’s surface, our planet’s evolutionary history, the interior dynamics of distant worlds, and materials science.
“This honor is a fitting tribute given the profound impact Dave’s work has had throughout the geosciences,” said Earth and Planets Laboratory Director Richard Carlson. “His contributions have shaped our understanding of our world and now a piece of the world will forever bear his name.”
Many materials that form under extreme pressures cannot retain their structures when brought to ambient conditions, which is what makes this discovery so exciting. Davemaoite, which was discovered encased inside a super-deep diamond, is only the second high-pressure mantle silicate ever seen on Earth’s surface. The other, named after Nobel laureate Percy Bridgman, was found inside a meteorite.
“The two form an exclusive club as the only lower-mantle silicate minerals confirmed in nature.” Fei said.
An illustration of the two pathways for obtaining high-pressure materials in nature—from mantle rocks that rise from the deep interior and as the result of meteorites crashing to Earth at breakneck speeds. Image is courtesy of Yingwei Fei.Together davemaoite and bridgmanite represent two distinct pathways for obtaining high-pressure materials in nature—from mantle rocks that rise from the deep interior and as the result of meteorites violently crashing to Earth at breakneck speeds. Laboratory scientists at Carnegie’s Earth and Planets Laboratory recreate both deep mantle conditions and the shock compression of a meteorite strike using a variety of research techniques that involve presses, anvils, and lasers.
The International Mineralogical Association’s Commission of New Minerals, Nomenclature, and Classification approved the davemaoite name. Minerals can only be properly named after their discovery in nature—even long-theorized or laboratory produced materials More than 50 minerals have been named in honor of Carnegie scientists, including hazenite, found in California’s Mono Lake, after current faculty member Robert Hazen. Earlier this year, a mineral found in a meteorite that originated on Mars was named feiite in honor of Fei.
“The discovery of davemaoite inspires hope for finding other difficult high-pressure mineral phases in nature,” Fei said. “Being able to obtain more direct samples from the inaccessible lower mantle would fill in our knowledge gap regarding the chemical composition and variability of our planet’s depths.”
The International Mineralogical Association’s Commission of New Minerals, Nomenclature, and Classification approved the davemaoite name. Minerals can only be properly named after their discovery in nature—even long-theorized or laboratory produced materials More than 50 minerals have been named in honor of Carnegie scientists, including hazenite, found in California’s Mono Lake, after current faculty member Robert Hazen. Earlier this year, a mineral found in a meteorite that originated on Mars was named feiite in honor of Fei.
“The discovery of davemaoite inspires hope for finding other difficult high-pressure mineral phases in nature,” Fei said. “Being able to obtain more direct samples from the inaccessible lower mantle would fill in our knowledge gap regarding the chemical composition and variability of our planet’s depths.”
Scientific Area:
Earth & Planetary Science
Reference to Person:
Yingwei Fei
Reference to Department:
Earth and Planets Laboratory
News Topic:
Earth/Planetary Science
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