“A record-breaking expedition to drill into rocks at the bottom of the Atlantic Ocean has given scientists their best glimpse yet of what the Earth might look like underneath its crust,” reports Nature. “Researchers extracted an almost uninterrupted 1,268-metre long sample of green-marble-like rock from a region where Earth’s mantle — the thick, interior layer that makes up more than 80% of the planet’s bulk — has pushed up through the sea floor.”
“Ocean drilling provides the only access to samples of Earth’s deep interior that are key to understanding our planet’s formation and evolution,” says marine geologist Rosalind Coggon.
This rock from the Earth’s mantle also contains bits of other types of rock found in the Earth’s crust, indicating that the boundary between the Earth’s mantle and its crust is not as sharp and well-defined as seismographic data previously hinted.
A future challenge for geologists will be to drill beyond the boundary between crust and mantle to reach pristine mantle rock that hasn’t reacted with seawater. “We haven’t drilled into the real mantle yet,” says a Japanese petrologist. Such drilling might be carried out by Japan’s research ship Chikyū, if it can raise the millions of dollars needed to do so. “Mantle rocks are the most common part of our entire planet,” says marine geologist Aled Evans. “Sampling them would tell us something fundamental about what our planet is made of.”
In other news, a huge deposit of rare-earth elements has been found in a Norwegian volcano. Two billion tons of rare-earth elements were recently discovered in Wyoming, although environmental regulations may delay tapping that supply. Right now, China is the world’s largest refiner of rare-earth elements, accounting for as much as 95% of global production and supply in 2023.
Researchers recently discovered that a strange compound used to treat cancer can also be used to extract rare-earth metals from old computers, TVs, batteries, and cell phones.
