Looks like it might be die cut errors. Also discoloration on front side. Weighs 2.6 g. Comments please.
plating blisters, you'll find many like this in the early years of copper plated zinc cents, they've gotten better as the years went on but ya still see it today, contaminants under the plating reacts with the zinc causing it swell (hard blisters), or create gases (soft blisters), its considered damage... the toning or discoloration is just the way the copper plating reacts with any number of environmental substances.... http://www.error-ref.com/blisteredplating/
