Is this what is called an (unplated) cent? It looks just like an old steel penny, the picture is very close to the real color. but it is not magnetic. also look at the (D) mint mark. it looks like an (RPM), but its a 1990 so that makes it impossible. right? Is it post mint damage? this one has me stumped. thanks for your help--BILL
Looks like someone stripped the plating from that coin, it's because of the dull appearance that I say that.
The dull color, rough surface texture, presence of tiny bumps, and lack of clarity in the design indicate the copper plating was chemically stripped.
Either through chemical or environmental means, the copper layer was removed from this coin, and the zinc layer oxidized. I see no evidence of an RPM.