Scientists discovered traces of ancient life trapped inside a 2.5-billion-year-old ruby. The team, led by Chris Yakymchuk, professor of Earth and Environmental Sciences at Waterloo, ventured into Greenland to study the geology of rubies in hopes of better understanding how they are formed.
They found a ruby sample that contained graphite, a mineral consisting of pure carbon, during this research. Analyzing this mineral led the scientists to believe that this carbon is an ancient trace of early life.
Background: Not all treasure is silver and gold
Greenland is home to some of the oldest known deposits of beautifully colored gemstones. Diamonds, rubies, sapphires, lapis lazuli, quartz, and many other gemstones have been found there. According to the International Gem Society, rubies are red gemstones that belong to the corundum family. They are compact, dense, and the second hardest mineral after diamonds. They are rare and expensive.
Graphite, also known as plumbago or black lead, is a mineral consisting of pure carbon. This mineral can originate from chemical and mineral processes, but it can also be a promising biomarker. One way to tell the difference is by analyzing its atomic mass.
There are carbon atoms with a mass of 12, 13, and 14 atomic mass units. Carbon-12 atoms are easier to integrate into living cells than heavier carbon-13 or carbon-14 atoms, meaning carbon-12 atoms are usually associated with life forms.
Analysis: There’s something in the ruby
“The graphite inside this ruby is unique. It’s the first time we’ve seen evidence of ancient life in ruby-bearing rocks,” Yakymchuk said in a press release. By analyzing the isotopic composition of the carbon atoms in the graphite, the research team found an increased level of carbon-12, which indicated that it was, likely, alive once.
“Living matter preferentially consists of the lighter carbon atoms because they take less energy to incorporate into cells,” said Yakymchuk. “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.”
During the study, the research team also discovered that graphite not only links the gemstone to the ancient life form but that it was also necessary for the ruby to exist. Apparently, the graphite changed the chemical properties of the rocks surrounding it, creating optimal conditions for rubies to grow.
The team’s models show that no rubies could’ve possibly formed in that specific location without the graphite.
Outlook: A better understanding of the past
The graphite was found in rocks that were estimated to be over 2.5 billion years old. At this time, oxygen was not abundant in our planet’s atmosphere, and the only existing life forms were microorganisms and algae.
Finding and studying the graphite in the ruby led the researchers to understand how the graphite influenced and actually allowed the formation of the ancient rubies. Still, it also offered some insight into how these precious stones became so prevalent in Greenland.
“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,” Yakymchuk said.
The results of the study “Corundum (ruby) growth during the final assembly of the Archean North Atlantic Craton, Southern West Greenland” were recently published in Ore Geology Reviews. A companion study developed by the same team (The Corundum Conundrum: Constraining the Compositions of Fluids Involved in Ruby Formation in Metamorphic Melanges of Ultramafic and Aluminous Rocks) was published in Chemical Geology back in June.
Raquel is a forensic geneticist turned freelance writer. She has a knack for technology and a passion for science. You can follow her at scitechcorner.com and on Twitter @theRaquelSantos.