This diamond in Cullinan, South Africa contains the first evidence of a mineral, scientists have wanted for years.
(Thanks to Nester Korolev, UBC)
A slate in the hand may be quite continental, but diamonds are a geologist’s best friend.
For proof, look no further than a newly mined diamond, which is a mineral that has never been seen in nature until now.
The discovered mineral called calcium silicate perovskite (CaSiO3)— was found caught in a diamond unearthed from the South african Cullinan mine (most known for the world’s largest diamond in 1905, part of which now adorns the crown jewels of the United Kingdom). The findings, published online today (7 March) in the journal Nature, provides an important clue to the puzzle of how the Earth’s inner structure behaves. [Shine On: Photos of Dazzling Mineral Specimens]
Although rare, the eyes of the man, calcium silicate perovskite can be shockingly ordinary deep in the bowels of the Earth — in fact, it is considered the fourth most common mineral in the planet, especially prevalent in plates of oceanic crust that have deposited in the planet’s mantle at tectonic boundaries.
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Despite the mineral of the theory of prevalence, however, previous studies have never yielded observable evidence of its existence. It is believed to be located deep in the bowels of the Earth the mantle, but — about 700 km (435 miles) below the surface of the planet, the researchers said.
“No one has ever succeeded in this mineral stable on the surface of the Earth,” study co-author Graham Pearson, a professor at the University of Alberta’s Department of Earth and Atmospheric Sciences, said in a statement. “The only possible way of preserving this mineral in the surface of the Earth, when it is trapped in a rigid container like a diamond.”
In the new study, Pearson and his colleagues analyzed a small diamond (about 3 millimeters in diameter) excavated from Cullinan and less than 1 km (0.6 miles) below the surface of the Earth. Despite this relatively shallow depth, the researchers determined that the crystal is an example of a “deep diamond” that most likely had formed about 700 km below the earth’s surface, derived from a subducted slab of the ocean crust and exposed to some 240,000 atmospheres of pressure.
The amount of calcium silicate perovskite within the gem visible to the naked eye after the diamond is polished, the researchers wrote, but proper analysis and imaging requires an international effort. X-ray spectroscopy tests confirmed that the diamond contain calcium silicate perovskite — perhaps the first intact specimen ever seen.
“Diamonds are really a unique way of seeing what is in the Earth,” Pearson said. “And the specific composition of the perovskite inclusion in this special diamond is very clear and the recycling of oceanic crust in the Earth’s lower mantle. It provides fundamental evidence of what happens with the fate of the oceanic plates as they descend into the depths of the Earth.”
Originally published on Live Science.