By-product metals are technologically essential but have ...
2015-4-3 · In the case of indium, for instance, typical concentrations in the zinc host ore are only a few parts per million , too low to mine for indium itself. Thus, nearly all indium production occurs as a by-product of zinc (with much smaller amounts from tin and copper ores, also as a by-product) . In contrast, silver sometimes has deposits that are ...