It doesn't look like a depression that would be made by the steel ball tip measuring the hardness. Can you post a better close-up? Not just an enlargement of this photo, but a new photo that is cropped and resized before posting the "Full Image". Chris
Could it have ended up between the die and planchet when struck? It is tiny and easy to miss it. Thanks guys for all your input.
It looks 'brassy', and it looks like a small ball of brass something was struck into the coin. (based on the photos only)