Improperly Annealed or PMD Half Dollar

[DC METRO CRH]

Hello. I found this 1976 Bicentennial Half Dollar searching through a $500 box. Is this an example of an "Improperly Annealed" or "Sintered" coin or is it just some sort of PMD? The obverse looks more like copper and the reverse and edges look normal.
Thanks for your help!

 

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[enamel7]

Looks like pmd to me.

 

[huntsman53]

Looks like pmd to me.

Yep, likely environmental contaminants!


Frank

 

[DC METRO CRH]

Thanks guys!