I met this source at the Tucson Gem Show in 2020. It is a foundry, a factory or workshop that melts and casts metals, located in Michigan which specializes in Copper. I was able to speak with the foundry’s owner and get detailed explanations about the difference between Native Copper and Copper nuggets and how each one is cleaned and treated. Michigan used to have a large commercial Copper mine, but it has been closed for many years. During its heyday, the Copper mine was so productive that there is still plenty of Copper in the slag-piles and along roadways that can be easily gathered.