>>64072961
Despite the US being a major producer, copper was in such demand during WW2 that we started making pennies out of steel and when the Manhattan Project decided to pursue electromagnetic isotope separation alongside gaseous diffusion (and liquid thermal diffusion too, which ended up being a bust) and needed a gorillion miles of wire they couldn't easily source 5,000 tons of copper so instead they borrowed 14,500 tons of silver coins from the Department of the Treasury, melted them down, and used it to build giant mass spectrometers. Post-war, the silver was gradually replaced by copper coils and returned to the Treasury (all but 0.036% of it, which is a ludicrously small amount of wastage for any type of manufacturing process)