Meteorites key to the story of Earth's layers »

A new analysis of the chemical make-up of meteorites has helped scientists work out when the Earth formed its layers. The research by an international team of scientists confirmed the Earth's first crust had formed around 4.5 billion years ago. The team measured the amount of the rare elements hafnium and lutetium in the mineral zircon in a meteorite that originated early in the solar system. "Meteorites that contain zircons are rare. We had been looking for an old meteorite with large zircons, about 50 microns long, that contained enough hafnium for precise analysis," said Dr Yuri Amelin, from The Australian National University (ANU) Research School of Earth Sciences. "By chance we found one for sale from a dealer. It was just what we wanted.