This is why you may want to get an XRF analyzer if you're buying material from the cheapest supplier in those quantities. For the rest of us, it's ad-hoc tests: CCA wire melts with a match flame, CCS gets attracted to a magnet, for CCC there's no obvious test, and if you can find legit copper conductor stockpile it now.

Having said that, if you read the original discussion, https://news.ycombinator.com/item?id=47304934, it looks like he brought this upon himself.

There are Copper mining and smelting operations in Europe. When all you want is lowest cost, these are the waters you tread.

previously https://news.ycombinator.com/item?id=47304934