4.4 Billion-Year-Old Zircon Crystal Reveals Earth's Infancy

A fragment of Zircon found in Western Australia's Jack Hills region formed nearly 4.4 billion years ago, according to a new study. Researchers say that the gem is the "oldest piece of Earth."

Scientists at University of Wisconsin-Madison and colleagues also found that the earth cooled down much sooner than previously thought, providing a new insight into earth's infancy.

Their research found that earth's crust formed nearly 160 million years after the formation of other planets in the solar system. Other researchers had said that the earth was a fiery ball of molten rock, whose crust took 600 million years to solidify, according to AFP.

According to the researchers, earth's crust began to form soon after the formation of solar system and that water began appearing during the planet's early years. "The study reinforces our conclusion that Earth had a hydrosphere before 4.3 billion years ago," said John Valley, lead author of the study.

For the study, Valley and colleagues looked at atoms of lead in zircon using a new technique called atom-probe tomography and secondary ion mass spectrometry. Researchers determined the age and thermal history of zircon by estimating the mass of lead atoms.

Their research confirmed that zircon from Australia's Jack Hills region crystallized some 4.374 billion years ago, AFP reported.

Zircons last Forever                                                                                                                          

Zircon (ZrSiO4) is a trace mineral found in many kinds of rocks. The mineral is considered to be a tiny time capsule that has recorded earth's geological history. The crystals are sturdy and resist chemical changes. Zircons crystal has radioactive element uranium, which is converted to lead at a steady rate, making zircon the most reliable time-keepers.

The zircon crystal used by Valley and colleagues in the study is now confirmed to be the oldest known material formed on earth, according to a news release

The latest estimation of zircon's age also could help researchers understand how life formed on earth and how it could appear on other planets.

"The zircons show us the earliest Earth was more like the Earth we know today," Valley told Livescience. "It wasn't an inhospitable place."

The study was funded by National Science Foundation, Department of Energy and the NASA Astrobiology Institute and is published in the journal, Nature Geoscience.