Residue found in 2.5 billion-year-old ruby linked to ancient life

We know the earliest life that appeared on the surface of our planet wasn't complex life as we know it today. Rather, ancient life would've been much simpler than humans, plants, and various animals. Scientists have made a very interesting discovery while analyzing some of the oldest colored gemstones in the world.

A research team from the University of Waterloo led by Chris Yakymchuk initially set out to study the geology of rubies in a quest to understand the conditions necessary to form rubies. While researching in Greenland, a continent known to contain the oldest deposits of rubies in the entire world, the researchers discovered an interesting sample. A ruby they discovered contained graphite, which is a mineral consisting of pure carbon. When the carbon was analyzed, the team discovered it was what remained of ancient early life on the planet.

Yakymchuk said the graphite discovered inside the ruby was unique, and its discovery is the first time any evidence of ancient life has been discovered within ruby-bearing rocks. The discovery of graphite within the ruby-bearing rock also gives the researchers an idea of how the rubies formed at that particular location. Yakymchuk points out that it's impossible to determine how rubies formed by inspecting their color and chemical composition alone.

With the discovery of graphite, the team analyzed a property known as the isotopic composition of carbon atoms. Scientists know that 98 percent of all carbon atoms have an atomic mass of 12, but some heavier forms have a mass of 13 or 14. In the sample the team analyzed, the high quantity of carbon-12 in the graphite led them to conclude that the atoms were once a component of ancient life.

They believe the graphite represents the remains of dead microorganisms, like cyanobacteria. The rocks where the graphite was discovered were older than 2.5 billion years, which hails to a time on Earth when there wasn't abundant oxygen in the atmosphere. The only life on the planet at this time was in the form of microorganisms and algae films. In this particular location, the existence of the graphite changed the chemistry of rocks surrounding it, allowing the formation of rubies.