According to The Official Price Guide to Mint Errors:
A coin struck on a blank or planchet which has stuck in the Annealing Drum and is partially or completely coated with a sintered coin metal dust, showing on the coin as a thin hardened coating, usually of a darker color.
I'm just learning of this myself, took some
As for yours, possibly
Looking closer at yours, sure looks like the same characteristics with the golden tone around the darker section.