i bought a bar which is supposed to be a copper rod then i found out it has nothing to do with copper + it has weird thing for example if i use sand paper to scrub it its color will be silver if i leave it for a couple of days its color goes to gold if i use it in a battery it goes dark to black and don‘t think copper does that what do you think that is
It sounds to me like it's probably silver. Clean silver will look, well, silver. If it tarnishes in air, it has a golden appearance. The dark color is possibly silver sulfide, which can form on electrical contacts. Depending on what you're using it for, it may work as an acceptible substitute for coppor - silver is a better electrical conductor than copper, for example.
