NASA’s Perseverance Rover recently surprised scientists by discovering minerals that form rubies and sapphires embedded in pebbles on Mars. The rover detected tiny corundum grains while exploring the terrain of Jezero Crater.
What made the discovery surprising is that corundum is usually formed by extreme heat and pressure created by tectonic activity. Mars, however, unlike Earth, does not have the type of plate tectonics that creates such a process. Scientists believe that meteorites striking the Martian surface may have formed the gems by heating and compressing the dust.
According to New Scientist, researchers initially noticed corundum while examining a rock known as Hampden River with Perseverance’s SuperCam instrument.
“[Corundum] usually is associated, on Earth, with tectonism. It’s a very specific environment – you have to have a very silica-poor environment, very aluminium-rich,” researcher Ann Ollila of Los Alamos National Laboratory said during a presentation at the Lunar and Planetary Science Conference on March 16.
“I was very surprised,” Allan Treiman of the Lunar and Planetary Institute in Texas, who wasn’t part of the study, said during the conference. “In retrospect, one might not have been, because there are aluminium-rich outcrops elsewhere on the planet and there are impacts, but I thought it was very shocking to see this.”
How did researchers come to this conclusion?
SuperCam can evaluate a material’s composition using several methods. One includes using lasers. They either burn off the material’s surface or excite luminescence. Researchers then use two cameras to observe the light it produces. When hit with the SuperCam laser, the Martian grains shone brightly. In tests, Hampden River lit up almost exactly the same as rubies examined in the lab. This suggests the rock contained microscopic corundum grains.
The Perseverance Rover also found two other rocks, named Coffee Cove and Smiths Harbour, which, when studied, also suggested the presence of corundum. However, it was hard to determine whether the corundum grains in the images were sapphires or rubies because they were less than 0.2 millimeters across.
“I would love to be able to pick one of those up and analyze it and see if it looks red,” said Ollila.