Copper Disk

Found this disk in a roll of pennies 2 nights back.
My digi-cam doesn't have a macro closeup setting, so this is the best I could do for a close up.
The left coin is a '82 copper, the right is '94 Zinc (picked for color comparison). The overall size
(height & width) is that of a penny, although it's a bit thinner - this could be due to the lack of a
rim on both sides.
It weighs 2.85-2.86 gr, less than a pre '82, but more than a Zinc.
I speculate that someone rubbed a pre '82 down w/ some sort of abrasive (both sides), hence the
weight reduction. The resulting surfaces are fairly smooth, w/ a few surface scratches.
Other theories?
JD
My digi-cam doesn't have a macro closeup setting, so this is the best I could do for a close up.
The left coin is a '82 copper, the right is '94 Zinc (picked for color comparison). The overall size
(height & width) is that of a penny, although it's a bit thinner - this could be due to the lack of a
rim on both sides.
It weighs 2.85-2.86 gr, less than a pre '82, but more than a Zinc.
I speculate that someone rubbed a pre '82 down w/ some sort of abrasive (both sides), hence the
weight reduction. The resulting surfaces are fairly smooth, w/ a few surface scratches.
Other theories?
JD