Washington Splitting?

[Jonny20302]

I came across a Washington Dollar in a mint roll that has cracking all around the outside edge. I've seen clamshell coins but am not sure if this is related. The face and back of the coin have excessive blackening from what appears to be the washing process. I'm wondering if it was still hot when washed. Has anyone heard of this or have any theories?

[diamond]

I've seen cracking on the edge before, usually far more serious than this. It is usually ascribed to the "hard upset" that the planchet receives. I seem to recall that the dollar planchets are not heat softened (annealed) before they're sent through the upset mill. I used to know the reason, but memory fails me at the moment. I'll try to look it up. The dark coloration has been attributed to improper annealing (excessive heat or prolonged exposure to heat) but I have not seen any published evidence supporting this conjecture. There are other causes of mint discoloration.