The ancient Aztecs believed gold was in fact “the sweat of the sun”. Though this isn’t true, the phrase is a highly accurate metaphor.
Gold, like most heavy metals, are forged inside stars through a process called nuclear fusion. In the beginning, following the Big Bang, only two elements were formed: hydrogen and helium. A few hundred million years after the Big Bang, the first stars were blazing away with their nuclear fires. These nuclear fires forced lighter elements together to make slightly heavier elements, and these nuclear reactions released a huge amount of energy.
Gradually, these early stars began making elements such as carbon, nitrogen, oxygen — working their way up through the periodic table towards iron. But there was still no gold in the Universe. Once these earlier stars ran out of light elements to burn, they kicked in on the heavier ones.
Finally, as they burnt silicon to make iron, they exploded as a supernova, and for a few short moments, each star would release as much energy as all the regular stars in that galaxy put together.In that cataclysmic explosion, for the first time, atoms of gold were manufactured — and then hurled out into the Universe, along with the other debris from that explosion.
On Earth, gold finally reached us some 200 million years after the formation of the planet when meteorites packed with gold and other metals bombarded its surface. During the formation of Earth, molten iron sank to its centre to make the core. This took with it the vast majority of the planet’s precious metals — such as gold and platinum. In fact, there are enough precious metals in the core to cover the entire surface of Earth with a four-metre thick layer.