Meteorites delivered gold to Earth

When Earth formed 4.55 billion years ago, iron sank to the center to form the core, and any precious metals would have been drawn down with it, theoretically leaving the mantle devoid of gold, platinum, and osmium.

Earth's silicate mantle contains up to 1,000 times more gold than predicted by standard planetary formation models, creating a scientific mystery that required explanation.

A final burst of meteorite impacts around 3.9 billion years ago, known as the "terminal bombardment," delivered the precious metals we can now access in Earth's crust. This event is evidenced by the cratering still visible on the Moon.

Researchers developed an innovative technique using tungsten isotopes as a proxy for precious metals, since tungsten behaves similarly to gold but comes in measurable isotopic forms that reveal meteoritic input.