Gold
Where did gold come from?
Gold is not made in ordinary stellar fire; most of it was probably forged in seconds during extremely violent events such as neutron star collisions.
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In three stops
Where were its atoms born?
Gold is heavier than iron, so ordinary stellar fire cannot make it. It needs “rapid neutron capture”, where nuclei grab many neutrons in a very short time. The strongest candidate is the collision of two neutron stars: in 2017 such a collision was observed both in gravitational waves and in light, with signs of heavy elements.
How did it form on Earth?
As Earth formed, most of its gold sank into the core along with iron. Much of the gold in today's crust is thought to have arrived later with meteorites. Hot underground water dissolves gold and deposits it in cracks in the rock, forming gold veins.
What did humans make of it?
Because gold does not tarnish and can be found pure in nature, it was among the first metals people knew. Gold objects about 6,500 years old were found in the Varna cemetery in Bulgaria. Today gold is also used in the circuits of phones and computers.
Did you know?
All the gold ever mined, put together, would form a cube about 22 metres on each side.