But now I are gotta find out why freshly mined lead has radioactive lead-210 in it but in old mined lead it has already decayed, since the lead atoms themselves all being the same age. Must have to do with trace elements decaying into lead-210
Yeah. Lead-210 has a half-life of about 20 years, but it’s part of the decay chain for uranium-238, and there’s enough of that in lead _ore_ that basically all freshly mined lead has some lead-210 in it. Along with a bunch of other radioisotopes, but those are different chemical elements so they are separated out by smelting.