Copper is slightly harder than silver or lead, so maybe it was scraped hard by a silver coin or a piece of lead. Not a mint problem. Maybe a chemistry or engineering teacher wanted to demonstrate the Moh's hardness scale. No way of telling easily. jim
No,just weigh it,a copper penny weighs 3.11g give or take. Any minor fluctuations from that are common due to ware ect. Any major difference should be noted
Here is another possibility for what your coin may be. It looks like it has some improperly mix alloy as well. http://www.error-ref.com/alloy-errors-intrinsic-metallic-inclusions/ You should try to post complete photos of both sides.
Looks like a choke collar. But seriously, just tuck it away. It's not worth grading, it's not worth testing, it's just not worth the cost to do anything to it.
Someone will yell at me for this but....take a qtip and see if you can gently wipe off any "silver". See if it comes off. Or, get closer in with your scope and see if its on the surface. Weird that the high devices on the date dont look black'ed...you'd think if something rubbed over it the date would have picked some of it up.
Very interesting so I sent this coin in to ngc it seems to me it has never been found before struck in obverse silver fragments i wanted to see all your guy's input on this coin it turned out to be a mint error info would help