another verdigris ?

ad4400

If a coin already has spots do those existing spots get worse over time? If the coin is already slabbed, does the slab mitigate further worsening? Would cracking it out accelerate the process? Or are the spots not self perpetuating?

ColonialCoinUnion

Depends what the spots are.

ad4400

To clarify, I beleive the spots are verdigris spots. Not sure if the pic will help but there are green spots around the rim, see above the D in United, by the mint mark, above the buffalo's head, and along the rim by the tail.