“This is the oldest and the best dated of all the crystals that have been reported,” said John Valley, lead study author and professor in the Department of Geoscience at the University of Wisconsin-Madison.
This crystal is a translucent red, Valley said, but glows blue when bombarded with electrons. At 400 micrometers long, its biggest dimension is just a tad larger than a house dust mite, or about four human hairs. Scientists say the crystal’s chemistry suggests that the temperatures on Earth 4.4 billion years ago would have supported liquid water, and therefore perhaps life.
Our planet is thought to be about 4.5 billion years old, but the oldest fossils we have so far are about 3.5 billion years old, one billion years younger than the recently discovered piece of zircon.