Arsenical copper would seem to indicate a precise knowledge of metallurgy.............
They didn’t have TV. Also, copper is generally found with arsenic in it.
https://search.brave.com/search?q=copper+arsenic&summary=1
Nice arsenical copper bust from Mesopotamia:
https://en.wikipedia.org/wiki/Arsenical_copper
More like a rudimentary knowledge. Perhaps even no knowledge - they might have mined it in that state.