4.4 billion years: zircon crystal is oldest piece of Earth

[Jamie D]

Rock around the clock: zircon crystal is oldest piece of Earth

Reuters | William Dunham



To put it mildly, this is one gem of a gem.

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.

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4.4 billion years ago is classified as part of the Hadean Eon.

Biogenic graphite dating to 3.8 billion years before present has been identified from western Greenland.  Fossilized algal and bacterial mats have been found in western Australian which are nearly 3.5 billion years old.