For the first time, evidence of ancient life was discovered inside a sapphire stone


Sapphire, which formed in the Earth’s crust 2.5 billion years ago, bears evidence of early life, writhing in the planet’s mud.

Geologists have discovered the remains of a form of pure carbon called graphite, which they say is likely biological in origin, and the remains of some ancient microorganisms before the emergence of multicellular life on Earth.

“The graphite inside this sapphire is really unique,” said geologist Chris Yakimchuk, from the University of Waterloo in Canada. It’s the first time we’ve seen evidence of ancient life in sapphire-bearing rocks. The presence of graphite also gives us more clues to determine how sapphires formed at this location, which is impossible to do directly based on the sapphire’s color and chemical composition.”

Sapphire is a variety of the mineral aluminum oxide – a crystalline form of aluminum oxide. It forms under extreme heat and pressure at the Earth’s tectonic boundary, where tectonic subduction and collision create the necessary environment. The stones are imbued with their deep hues through the presence of the rare element chromium – the more chromium, the redder the gemstone.

Like all minerals, sapphire varies in purity and clarity. Formation processes can result in the presence of impurities in the gemstones. This may make these stones unsuitable for jewelry, but they are great for science.

For example, a mineral thousands of kilometers underground that would not otherwise remain on the surface was found preserved in diamonds. The surface minerals in other diamonds that formed deep in the Earth have led to a better understanding of how tectonic subduction can drag surface material down.

Yakimchuk and his team were seeking to better understand corundum formation processes by studying sapphires in Greenland, where one of the world’s oldest known deposits of the mineral is located. While studying these samples, they found inclusion of graphite.

Graphite can be formed abiotically, that is, through chemical and mineral processes; However, it can also be an important biomarker. One way to tell the difference is to identify the isotopes of carbon, which are forms of the same element with different numbers of neutrons in the nuclei, and therefore different atomic masses.

Carbon-14, for example, is radiocarbon best known for its use for accurate dating of physical artifacts; It forms abiotically in the Earth’s atmosphere. The lightest natural isotope of stable carbon on Earth is carbon 12. This isotope is abundant on Earth and occurs in living organisms.

The team found that the graphite in the sapphire was carbon 12, and in abundance consistent with organic origin. Because we know the age of the gem, this allowed researchers to narrow down that organic origin, because life on Earth 2.5 billion years ago was very limited.

“Living matter is preferentially composed of lighter carbon atoms because it takes less energy to be incorporated into cells,” Yakimchuk said. Based on the increase in the amount of carbon 12 in this graphite, we concluded that the carbon atoms were once ancient life, most likely dead microorganisms such as cyanobacteria.”

This led to some clues about how sapphires were formed as well. Corundum does not form in environments that contain a lot of silica.

Graphite indicates a fluid that will help transport silicon dioxide out of the rock, creating the environment for the formation of aluminum oxide in the first place.


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