So, TPG's Are Calling These "Impproperly Annealed"

With the general condition of these, I don't think these are anything more than PMD. If they were unc coins, then maybe they could be some sort of error.

BTW, annealing is a heating of the blanks to soften them for striking. I'm guessing overheating would cause discoloration, like the blue tinge you'll see if you sharpen a blade too quickly on a grinding wheel.

I think we're confusing terms and coins here folks-

A "stintered" or improperly annealed coin is caused by being overcooked in the annealing bin. Before the coins are struck- they are heated to make them softer and more malleable between the dies. This increases die life. If a coin gets stuck in the bin for too long, it is overheated and fine particles of metal adhere to it. The result is a coin that ranges from dark grey to black while still being fully lustrous. These were called "Black Beauties" in the 1950s when they were first noticed on nickels. Recently, in the last several years, Fred Weinberg has promoted them and I believe that is what let to the TPGs attributing them (he has great sway with the TPGs). That being said, the coin above is not.

What it looks like is pictured above- is a coin with a ribbon of copper rolled into the planchet strip before it was punched. Yes- this is probably more often a post-mint alteration. But they do occur, I have one I came across last week. I scratched it very deeply (don't do this) because I was certain it was just a thin plating. I was wrong- the copper goes deep into the planchet. I don't have enough time to explain the difference between alloy impurities and a coin struck through copper debris, but I hope I was helpful on the subject of "stintered" coins.