@RH, no problem--we are glad to have you here. Using a good balance may help to determine whether this is a blank planchet vs. a copper slug. Often times schools have this sort of equipment in their science department, so if you, or your nephew, or your cousin, or whoever is in school, they might be able to weigh it four you. In the meanwhile, it probably is worth putting aside until you have more information. If you are storing your coins in 2x2s, this is a good candidate for that.
"The danger we all now face is distinguishing between what is authentic and what is performed."