We have completed maintenance on DiscoverMagazine.com and action may be required on your account. Learn More

Earth's Inner Fort Knox

Searching for a pot of gold? Try the center of the Earth

By Anne Wootton
Sep 1, 2006 12:00 AMNov 3, 2019 7:29 PM

Newsletter

Sign up for our email newsletter for the latest science news
 

More than 99 percent of Earth's gold is missing—it all sank to the center of the planet billions of years ago. In fact, says geologist Bernard Wood of Macquarie University in Australia, there's enough gold in Earth's core to coat its surface in 1.5 feet of the stuff. How did it get there? Earth formed from a series of smaller planetesimals that crashed together over the course of 30 million to 40 million years. Wood deduced how much gold ought to be present in Earth's crust by comparing the crust's composition to that of meteorites similar to the planetesimals. He concluded that the crust was depleted of gold, platinum, and nickel and suggests that all these iron-loving elements were pulled into Earth's iron-rich core while its surface was still an ocean of molten magma. In fact, if meteorites hadn't later deposited gold on Earth's surface millions of years after its core had fully formed and its crust had cooled, gold would be even more rare and expensive than it is today. Wood has calculated that 1.6 quadrillion tons of gold must lie in Earth's core. This may sound like a lot, but it is really only a tiny percentage of the core's overall mass—about one part per million. The core holds six times as much platinum, Wood notes, "but people get less excited about that than gold."

1 free article left
Want More? Get unlimited access for as low as $1.99/month

Already a subscriber?

Register or Log In

1 free articleSubscribe
Discover Magazine Logo
Want more?

Keep reading for as low as $1.99!

Subscribe

Already a subscriber?

Register or Log In

More From Discover
Recommendations From Our Store
Shop Now
Stay Curious
Join
Our List

Sign up for our weekly science updates.

 
Subscribe
To The Magazine

Save up to 40% off the cover price when you subscribe to Discover magazine.

Copyright © 2024 Kalmbach Media Co.