1921 S Wheat Cent - Curious Erosion

I'd say it has a lamination problem. cool

1921 it is bronze. I agree with COINFROG about acidic contact, the flow of the texture give us indications of. In the same time I will say that this interaction with acidic contact is combine with an ex-foliation of the material. Due to the age I consider normal for an planchet which was not perfect osmogene.

Seems like quite a bit of metal has eroded away—what's the weight? I agree that the pattern of erosion is quite interesting.

Noting the circulation wear and the sharpness of the affected areas, it looks like it was altered post strike.

Not a mint error sure. But if the metal will not separate structural you will never have this effect near the rims on the Observe. Some acidic environment acted as an leant for this separation. What stay in the line with my opinion is clear that the only the missing parts has those strait lines where the acidic enter between the bronze crystals. Do not forgot that the bronze is a metal in the cubic crystalline metals family, this mean that any acid will follows the molecular lines.

Second: The metal fatigue act also as a leant of separation.