Thermodynamic model identifies how gold reaches Earth's surface
phys.org
phys.org
(No idea whether that is the right sizing, but I could totally imagine it being the case)
edit:
"...The estimated amount of gold ever mined is around 212,582 tonnes, according to the World Gold Council. This is roughly equivalent to a cube of gold that's about 22 meters on each side..."
https://www.gold.org/goldhub/data/how-much-gold
https://www.usgs.gov/faqs/how-much-gold-has-been-found-world
The explanation I received was that the densest atoms (e.g. gold) migrated into the core over billions of years (because: gravity; gold is twice as dense as lead).