Register for an account

X

Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.

X

Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Planet Earth

#53: Did Earth’s Gold Come From Outer Space?


Money never grows on trees, but precious metals do sometimes fall from the sky.

By Elizabeth SvobodaDecember 27, 2011 12:00 AM
Earth’s Gold
iStockphoto

Newsletter

Sign up for our email newsletter for the latest science news

The platinum in your wedding 
ring and the gold in your dental fillings most likely arrived on Earth in a furious meteoric bombardment 200 million years after the planet’s formation, University of Bristol geologist Matthias Willbold reports. According to standard planetary formation models, the gold, platinum, and tungsten that were present when Earth was born should have quickly bonded to iron and sunk into the planet’s core. Those precious metals are thousands of times more prevalent on the surface of Earth and in its mantle than the models predict.

Willbold proposes that a colossal meteor shower about 4 billion years ago deposited the additional bling. To test his theory, he measured the isotopic mix of tungsten in rocks from an ancient formation that predates the proposed meteor shower. He then compared the readings with isotopes found in more recent rocks. “If you look at really ancient rocks in Greenland, the tungsten composition is different,” he says.

Willbold’s group reported in a paper published last September that levels of certain isotopes in the newer rocks are slightly lower than in the old ones, indicating an addition of precious metals similar to what meteoric impacts would have produced. Beyond sprinkling the planet with riches, Willbold believes the meteor shower could have helped deliver the ingredients necessary for life: “Most of the water on Earth today may have been brought during that late bombardment.”

2 Free Articles Left

Want it all? Get unlimited access when you subscribe.

Subscribe

Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%

Subscribe

Already a subscriber? Register or Log In