Diamonds And Deep Secrets
Mukesh Kumar
| 18-12-2023
· Science Team
In a groundbreaking discovery, scientists have identified calcium silicate (CaSiO3) chalcocite on the Earth's surface for the first time.
Although it is likely the fourth most abundant mineral on Earth, it has remained unseen by human eyes because it tends to destabilize when situated more than 650 kilometers below the surface.
So, how did this mineral reach the surface? The answer lies in its association with diamond lobes. The diamond in question was discovered at the Cullinan diamond deposit in South Africa, located less than a kilometer from the Earth's surface.
Graham Pearson, a geochemist in the Department of Earth and Atmospheric Sciences at the University of Alberta, points out that maintaining the stability of this mineral on the surface is a challenge.
It can only be preserved if it's enclosed in a robust container, like a diamond.
The mantle, positioned between the Earth's core and crust, serves as the primary solid layer. Over extended periods, the Earth's tectonic movements transport rocks and minerals between these layers.
Scientists typically deduce the mantle's composition based on materials found in the crust. However, certain minerals transform when they depart the high-pressure and high-temperature conditions of the mantle.
Diamonds, resistant to deformation, have emerged as the sole direct window into the mantle, offering insights into its hidden mysteries.
For the first time, scientists have uncovered a previously unknown mineral, calcium silicate (CaSiO₃) chalcocite, from a diamond extracted deep within the Earth.
This mineral can only form in the extreme conditions of the lower mantle. It is estimated that CaSiO₃ makes up 93% of the lower mantle, but until now, its existence was speculative.
This groundbreaking discovery opens the door for in-depth studies.
The diamond, a rare sample measuring only 0.031 millimeters in thickness, was formed at a depth of about 700 kilometers.
Unlike the majority of diamonds originating 150-200 kilometers below the Earth's surface, this unique specimen experienced a pressure 240,000 times greater than sea-level atmospheric pressure.
This intense pressure, responsible for the diamond's formation, created a stable environment, preserving the CaSiO3 within its crystal lattice as the diamond ascended to the surface.
Diamonds provide scientists with a distinctive perspective for studying the Earth's interior.
This discovery has already unveiled crucial information about mantle formation, illustrating the cyclical process of oceanic crust entering the Earth's lower mantle.
It serves as significant evidence in the exploration of the fate of the oceanic crust as it delves into the Earth's depths.
To confirm the mineral composition, researchers polished the diamond and conducted spectroscopic analyses, affirming the presence of the legendary CaSiO3.
Further studies will delve into the mineral's age and origin, expanding our understanding of the Earth's intricate geological processes.