No response to what the density of the rock is. That would tell a LOT. If it's below 7 g/cm3, then there's no chance it's highly metallic, because virtually every metal that can be found in native form has a density higher than that. Even copper is 8.9 g/cm3. So if the rock was 'mostly' pure copper, it'd be above 7 g/cm3 on average.
It COULD be a metal sulfide, but even then that means the XRF reading is utterly wrong.
It COULD be a PM telluride, but the XRF is STILL totally wrong in that case, and the density would be over 8 g/cm3.
The OP seems to be avoiding giving us the numbers of some really simple, really revealing tests.