I was talking with a colleague about the bronze snake of Numbers 21, because a student had referred to it as the "copper snake" on a test. (Bronze of course is an alloy of copper and tin.)
I seemed to remember that the Hebrew word doesn't differ, and sure enough, נְחשֶׁת can refer to either.
So we got to wondering how the translators differentiated it. I thought maybe the Septuagint would have used a different word. But I see that their common translation, χάλκεος, is also ambiguous.
Meanwhile, it turns out that the KJV mostly translates these words as "brass", i.e. copper & zinc!
Do we have a way of differentiating these? Do we guess based on chronology / archaeology? Or is it a shot in the dark?