The 4 billion-year-old crystal found in Australia is the oldest known piece of Earth's crust, and the zircon, as it is called, is stunning scientists. “This crystal is a translucent red but glows blue when bombarded with electrons,” said John Valley, lead study author and professor in the Department of Geoscience at the University of Wisconsin-Madison, according to a Feb. 24, 2014, CNN report.
The zircon’s blue glow when exposed to electrons is just one of the interesting discoveries coming from the oldest known piece of Earth's crust.
The 4 billion-year-old crystal was found on a sheep ranch in the Jack Hills region of Western Australia and scientists have determined that it is the earliest confirmed piece of the planet’s crust. Its precise age has been determined to be 4.4 billion years. The Earth itself formed 4.5 billion years ago as a ball of molten rock, meaning that its crust formed relatively soon thereafter, 100 million years later.
Even though the zircon is only 400 micrometers long, which is just a bit larger than a house dust mite or about four human hairs, scientists have learned from the piece that Earth's crust formed relatively soon after the planet formed and that the little gem was a remnant of it.
John Valley, the University of Wisconsin geoscience professor who led the research, said the discovery of the crystal suggests that the early Earth was not as harsh a place as many scientists had previously thought.
“The finding supports the notion of a ‘cool early Earth’ where temperatures were low enough to sustain oceans, and perhaps life, earlier than previously thought. The discovery that the zircon crystal, and thereby the formation of the crust, dates from 4.4 billion years ago suggests that the planet was perhaps capable of sustaining microbial life 4.3 billion years ago."
The 4 billion-year-old crystal findings were published on Sunday in the journal Nature Geoscience. The article emphasizes that the only physical evidence from the earliest phases of Earth’s evolution comes from zircons – even if they are only just a bit larger than a house dust mite.