I believe this is Condor's. The most spectacular missing clad layer on a half. It needs to look something like this: (and normal on the other side)
Coins missing the clad layer usually look like uncirculated pennies do. Coins like yours have just been glued for a project or left to accumulate some dirty gunk.
Not mine, does belong to someone here, it gets posted a lot. They found it in one of the half dollar bags that the mint sold directly to collectors.
Missing Clad Layer usually occurs just on one side of a clad coin. As mentioned yours is Post Mint Damage. Just Environmental Damage. Here is my latest example from my collection -
Not damaged. I don't consider tarnish as damage. Corrosion yes. Tarnish or toning no. Not one TPG considers tarnish as Environmental Damage unless it is so deep or dark it is considered a stain.
Thanks I didn't remember who's coin it was. I will relabel in the future. I kept that photo cause it's a great example and can show people what a genuine one looks like.