This is definitely a first for me and there really is not alot of information about this. Anyone have a lesson for me on this one?
Weigh it. Compare its weigh (in grams) to that of a standard quarter. If they weigh the same, it simply has a thin copper plating making it PMD. If it weighs more, then its plated and PMD. If it weighs significantly less, then you might have something but judging from the edge shot, my guess is PMD for electroplating.
Looks coper plated. Take a magnifying glass a look at the raised rim as it turns into the edge. See if you see any silver color cladding coming through the plating.
And if the weight is normal it is simply Environmental Damage The clad color changed due to exposure to the elements. Soil, dirt, sand, water, heat, cold.. that is all it is.
I have mentioned before.. I Metal Detect. I have found dozens of Quarters, Nickels and Dimes that have been affected by Environmental Damage. Here are examples of the Quarters I have found With a normal Quarter for comparison
A true error is considered an Off Metal error. That's when a Blank Planchet of another Denomination is struck, usually a smaller planchet, instead of the correct intended planchet. Here is an example of a Quarter struck on Cent Planchet.. it's thinner and smaller than a normal Quarter. NOT MY COIN