More on spots

[MikeKing]

I have a half cent with punctate blue spots kind of peppering the surface between the denticles and around the devices. I've seen crystals of copper sulfate, which are blue, in chemistry class, so I'm assuming this is a reaction of something with the copper. They are very tiny, pinpoint and all appear quite above the surface of the coin, almost like you could just pick them off. Is this something you see often, and is there a remedy for this? Is this what they call 'verdigris'?