Chemical tests of the mineral revealed that it contained radioactive uranium, thorium, and potassium isotopes.
For the first time, scientists have identified a previously unseen mineral in a diamond mined from beneath the Land crust. Calcium silicate perovskite is a mineral that forms under the extreme pressure and temperature conditions found in the lower mantle. Davemaoite is the mineral’s name.
The mineral, named after geophysicist Ho-kwang (Dave) Mao for his research on high-pressure elements, has a crystalline structure that forms under the extreme pressure and temperature conditions found deep within the Earth’s layer trapped between the core and the crust. Scientists have long predicted its existence, albeit subtly.
According to a study published in Science, calcium silicate perovskite, CaSiO3, is arguably the most geochemically significant phase in the lower mantle due to the fact that it contains elements that are incompatible with the upper mantle.
Chemical analysis of the mineral revealed that it contained radioactive uranium, thorium, and potassium isotopes. “Davemaoite can thus host three of the major heat-generating elements (uranium and thorium have previously been demonstrated experimentally) that contribute to heat generation in the Earth’s lower mantle,” the paper stated.
Researchers led by Oliver Tschauner of the University of Nevada’s Department of Geoscience examined a greenish, octahedral-shaped diamond dug up from the world’s largest opencast diamond mine, Botswana’s Orapa mine. The diamond was then sold to George Rossman, a mineralogist at the California Institute of Technology, and Tschauner began studying it for a study of minerals trapped in deep-Earth diamonds, according to Nature.
WHAT IS SO EXCITING ABOUT THIS DISCOVERY?
One of the most significant obstacles to studying rare Earth minerals formed deep underground is their proclivity for chemical structure loss when exposed to ambient conditions. The new discovery of the mineral, on the other hand, has the scientific community excited because it has retained its structure despite being unearthed decades ago.
One of the primary reasons is that it was discovered encased within a super-deep diamond, making it only the second high-pressure mantle silicate to be discovered on the Earth’s surface. Yingwei Fei, a geophysicist at the Carnegie Institution for Science, writes in an essay accompanying the research in Science, “No one has ever successfully recovered a high-pressure calcium silicate from the lower mantle.” This is because the high-pressure CaSiO3-perovskite is “unquenchable,” or unable to retain its structure when removed from its high-pressure environment.
The International Mineralogical Association’s Commission of New Minerals, Nomenclature has now recognised the mineral.
“The discovery of davemaoite paves the way for the discovery of additional difficult high-pressure mineral phases in nature. Obtaining additional direct samples from the inaccessible lower mantle would close a knowledge gap about the chemical composition and variability of our planet’s depths,” Fei said in a statement.
