In a first-of-its kind discovery, remains of ancient life has been found in a 2.5-billion-year-old ruby that formed in the Earth’s crust. According to geologists, the ruby contained pure carbon called graphite that was probably biological in nature as the remnants of an ancient organism that was around prior to multicellular life evolving on our planet.
Rubies are a popular gemstone in jewelry but how they form is very interesting as they are created from extreme pressure and heat in Earth’s tectonic boundaries. They are a form of the mineral corundum which is a crystalline type of aluminum oxide. The redder the ruby, the more chromium it contains.
Chris Yakymchuk, who is a geologist at the University of Waterloo in Canada, as well as his colleagues, wanted to study the corundum formation process so they decided to analyze rubies that are found in Greenland. In fact, Greenland has some of the oldest ruby deposits in the world.
While studying the rubies, the team discovered the graphite inclusion and were able to determine that the stone contained a lot of carbon-12 which indicated that it was organic. “The graphite inside this ruby is really unique. It’s the first time we’ve seen evidence of ancient life in ruby-bearing rocks,” Yakymchuk explained, adding, “The presence of graphite also gives us more clues to determine how rubies formed at this location, something that is impossible to do directly based on a ruby’s color and chemical composition.”
He went on to say, “Living matter preferentially consists of the lighter carbon atoms because they take less energy to incorporate into cells.” “Based on the increased amount of carbon-12 in this graphite, we concluded that the carbon atoms were once ancient life, most likely dead microorganisms such as cyanobacteria.”
Their discovery revealed valuable information regarding how the rubies were formed in the first place as corundum can’t form when there is an overwhelming amount of silica in the environment. Since there was graphite present, it seems to indicate that there was once some fluid there that would have aided in getting rid of some of the silicon dioxide that was in the rock. At that point, the corundum would have been able to form.
Their study was published in Ore Geology Reviews where it can be read in full.
A picture of the ruby can be seen here.