Scientists have confirmed that the tiny crystal found in Australia is the oldest piece of the Earth that has been discovered – at 4.4 billion years old. By using highly advanced dating techniques, geologists were able to determine the zircon fragment was created during the early stages of Earth’s formation. The first to identify and publish the crystal’s composition as zircon was the journal Nature Geoscience, on Sunday.
Although this is a recent discovery, the crystal was originally found 13 years ago, in 2001. The crystal was discovered on a sheep ranch in Perth, Australia. The area is an arid, low range of hills called Jack Hills, in the southwest region of the country.
John Valley, professor in the Department of Geoscience at the University of Wisconsin-Madison stated that the crystal is the oldest and best dated of all crystals. “The crystal is translucent red,” Valley stated. However, when blasted with electrons, the reaction creates a bright blue glow.
To determine the age of the zircon crystal, Valley’s team used two different dating techniques. First, the team isolated radioactive lead atoms deep within the crystal. The lead originally formed as Uranium, which decayed over time – the atoms were confined in the substance during the solidification of the Earth’s near-liquid crust. Using atom-probe tomography, Valley’s team was able to examine the lead for signs of altered radioactivity caused by atom decay. They were able to approximate the date of the Australian crystal at 4.375 billion years with a margin of error of 6 million years.
It is amazing that this crystal was even discovered. At only 400 micrometers in length, its largest spatial dimension is just larger than four human hairs placed side-by-side.
Scientists determined that the chemistry of the crystal, most notably the ratio of oxygen isotopes contained in it, advocates that temperatures on the Earth over 4.4 billion years ago would have sustained liquid water. Such findings suggest that Earth may have harbored life much earlier in its history than previously thought. Valley stated that what has been brought from the crystal’s discovery is that the Earth cooled in a quicker fashion than geologists previously conceived. The earlier formation of the Earth could have allowed for life to begin sooner and cause scientists to revisit the timeline of organic evolution.
Scientists and geologists date the Earth at around 4.5 billion years old – the first fossilized creatures dated at around 3.8 billion years old. Although direct evidence has yet to be found, life could have existed in the 800 million years prior to the first recorded carbon-based life forms. The date of 3.8 billion years ago signifies the existence of the first organisms found on Earth due to the presence of liquid water. Nevertheless, since the discovery of the tiny zircon crystal may hint at occurrence of liquid water over 800 million years before fossilized life, an earlier manifestation of carbon-based organisms could be possible.
“We’ll never know how much water there really was,” said Professor Samuel Bowring of the Massachusetts Institute of Technology, regarding the hypothesized nature of the earth, eons ago. However, he explained that with a modest interpretation of 4.4 billion year old zircon crystal coming from the granite in Australia, scientists are able to deduce that a hydrous planet existed from the beginning.
By: Alex Lemieux