Found - the oldest known piece of Planet Earth
Posted: 26 Feb 2014
Gem found on Australian sheep ranch is the oldest known piece of Earth, scientists find
Scientists using two different age-determining techniques have shown that a tiny zircon crystal found on a sheep ranch in Western Australia is the oldest known piece of our planet, dating to 4.4 billion years ago. Writing in the journal Nature Geoscience on Sunday, the researchers said the discovery indicates that Earth's crust formed relatively soon after the planet formed and that the little gem was a remnant of it.
John Valley, a University of Wisconsin geoscience professor who led the research, said the findings suggest that the early Earth was not as harsh a place as many scientists have thought.
To determine the age of the zircon fragment, the scientists first used a widely accepted dating technique based on determining the radioactive decay of uranium to lead in a mineral sample.
But because some scientists hypothesised that this technique might give a false date due to possible movement of lead atoms within the crystal over time, the researchers turned to a second sophisticated method to verify the finding.