Κυριακή, 3 Ιουλίου 2016

Extraterrestrial Opal Found in Meteorite in Antarctica


A meteorite has been discovered in Antarctica studded with gemstone fragments that are literally out of this world.


The small shards of opal are the first to be found on the surface of any asteroid, and indicate that water may have been delivered to Earth from elsewhere in the early history of the solar system.

Opal, used commonly in modern day jewelry, is formed from silca–a key component in sand–and water. When silica forms a watery solution it can, over millions of years, harden into the shimmering gemstone; some opals contain up to 30 percent water.


Images of one of the many pieces of opal found in meteorite EET 83309. At top right is a backscattered electron image (the long thin dark object is opal). At bottom left is an image of silica concentrations in opal and surrounding meteoritic minerals. At top left is an image of oxygen concentrations in opal and surrounding minerals. At bottom right is an image nickel concentrations in opal and surrounding minerals. Credit: H. Downes

The opal-carrying meteorite discovered in Antarctica, named EET 83309, is made up of thousands of pieces of broken of rock and mineral, indicating that it came from the surface of a larger parent asteroid. It has been examined by a team led by Professor Hilary Downes of Birkbeck College London, who explained in a statement:

Our evidence shows that the opal formed before the meteorite was blasted off from the surface of the parent asteroid and sent into space, eventually to land on Earth in Antarctica.


A backscattered electron image of the narrow opal rim surrounding a bright metallic mineral inclusion in meteorite found in Antarctica. The circular holes in this image are spots where laser analyses have been performed. Credit: H. Downes

And this is particularly exciting. The determination that the opal formed while the meteorite was still in space, and not while it sat in the Antarctic Ocean, lends credence to theories that life on Earth evolved after water was deposited on the planet’s surface by asteroids:

This is more evidence that meteorites and asteroids can carry large amounts of water ice. Although we rightly worry about the consequences of the impact of large asteroid, billions of years ago they may have brought the water to the Earth and helped it become the world teeming with life that we live in today.

Source: mysteriousuniverse.org

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