Question About 1988-D LMC

Looks like split plating. In the 80's the mintmark was still punched into the dies by hand. This often left an abrubt edge in the metal of the die where the mark was punched in. When coins were struck with the die, sometimes the plating on the plachet would split due to the pressure of the strike on this edge, allowing the zinc core to show through. At least that's how it was explained to me...

Dave

I see zinc! It's common when these things get struck, the plating is so thin on them that you get them quite often.