Aside from the evidence of > 2,000 years of lead and mercury poisoning, of course.
Humans have been naturally digging these things up and refining them since at least the Roman Empire [1] in the west and the earliest Chinese Dynasties in the East [2].
Humans have been naturally digging these things up and refining them since at least the Roman Empire [1] in the west and the earliest Chinese Dynasties in the East [2].
[1] https://sites.dartmouth.edu/toxmetal/more-metals/lead-versat...
[2] https://en.wikipedia.org/wiki/Mausoleum_of_the_First_Qin_Emp...