In July 2019, Gregory Dipple, a geologist at the University of British Columbia, Vancouver, hopped on a 119-seat charter flight in Yellowknife, Canada, and flew 280 kilometers northeast to the Gahcho Kué diamond mine, just south of the Arctic Circle.
Gahcho Kué, which means “place of the big rabbits” in the Dënësu̧łinë language of the region’s native Dené or Chipewyan people, is an expansive open pit mine ringed by sky-blue lakes. There, the mining company De Beers unearths some 4 million carats’ worth of diamonds annually.
But Dipple and two students weren’t there for gems. Rather, they were looking to use the mine’s crushed rock waste as a vault to lock up carbon dioxide (CO2) for eternity.
At Gahcho Kué, Dipple’s team bubbled a mix of CO2 and nitrogen gas simulating diesel exhaust through a grayish green slurry of crushed mine waste in water. Over 2 days, the slurry acquired a slight rusty hue—evidence that its iron was oxidizing while its magnesium and calcium were sucking up CO2 and turning it into to carbon-based minerals.
The CO2-hungry waste from the diamond mine is an exotic deep-earth rock, shot up to the surface in the volcanic eruptions that bring up diamonds.
For the rest of this article: https://science.sciencemag.org/content/369/6508/1156.full