Definitely not an expert on this. But IIRC most of the heavy metals, like gold, present at the earth's creation will have migrated to the core, due to their den

Definitely not an expert on this. But IIRC most of the heavy metals, like gold, present at the earth's creation will have migrated to the core, due to their density. However some heavy metals will have arrived by meteroite and I guess these will be relatively localized. Also various chemical and geological process will tend to separate out different elements over long timescales.