While analyzing some of the world’s oldest colored gemstones, researchers found University of Waterloo discovered coal remains that were once ancient life, encased in a 2.5 billion-year-old ruby.
The research team, led by Chris Yakymchuk, professor of soil and environmental sciences at Waterloo, set out to study the geology of rubies to better understand the conditions necessary for ruby formation. During this study in Greenland, which contains the oldest known ruby deposits in the world, the team found a ruby sample containing graphite, a mineral made from pure carbon. Analysis of this carbon indicates that it is a remnant of early life.
The graphite inside this ruby is really unique. This is the first time we have seen signs of old life in ruby-containing stones, ”says Yakymchuk. “The presence of graphite also gives us several clues to determine how rubies were formed at this site, something that is impossible to do directly based on the color and chemical composition of the ruby.”
The presence of graphite allowed the researchers to analyze a property called the isotopic composition of the carbon atoms, which measures the relative amounts of different carbon atoms. More than 98 percent of all carbon atoms have a mass of 12 atomic mass units, but a few carbon atoms are heavier, with a mass of 13 or 14 atomic mass units.
“Living matter consists primarily of the lighter carbon atoms because they take less energy to incorporate into cells,” Yakymchuk said. “Based on the increased amount of carbon-12 in this graphite, we concluded that the carbon atoms were once an old life, probably dead microorganisms like cyanobacteria.”
Graphite is found in rocks older than 2.5 billion years ago, a time on the planet when oxygen was not plentiful in the atmosphere and only microorganisms and algae films existed.
During this investigation, Yakymchuk’s team discovered that this graphite not only connects the gemstone with ancient life, but was also probably necessary for this ruby to exist at all. The graphite changed the chemistry of the surrounding rocks to create favorable conditions for ruby growth. Without it, the team models showed that it would not have been possible to form rubies in this place.
The study, “Corundum (ruby) growth during the last collection of the archaic North Atlantic craton, southern West Greenland”, was recently published in Ore Geology Reviews. An accompanying study, “Corundum conundrum: Limitation of compositions of liquids involved in ruby formation in metamorphic melanges of ultramafic and aluminum-containing rocks,” was published in the journal Chemical geology in June.
“Corundum (ruby) growth during the last collection of the archaic North Atlantic craton, southern West Greenland” by Chris Yakymchuk, Vincent van Hinsberg, Christopher L. Kirkland, Kristoffer Szilas, Carson Kinney, Jillian Kendrick and Julie A.Hollis, August 20 2021, Ore Geology Reviews.
DOI: 10.1016 / j.oregeorev.2021.104417
“Corundum conundrum: Limitation of compositions of liquids involved in ruby formation in metamorphic melanges of ultramafic and aluminum rocks” by Vincent van Hinsberg, Chris Yakymchuk, Angunguak Thomas Kleist Jepsen, Christopher L.Kirkland and Kristoffer Szilas, March 20, 2021, Chemical geology.
DOI: 10.1016 / j.chemgeo.2021.120180