It's highly irregular shape makes this more likely to a "bleb", the positive impression of a die erosion pit. These sometimes develop in late die states.
Which term do you feel is more correct ? Also if the die steel wasn't hardened properly I can see where the part with a low carbon factor would be softer and more prone to lose material gradually . Does this sound like what you're referring to ? Thanks .
I prefer "bleb", but it's merely a personal preference. There is no referee that determines which term is "official". Since I'm not a metallurgist, I can't comment intelligently as to the specific cause of the erosion pits. But it's always associated with a late die state.
I'm not sure what's going on with the Canadian coin, but it's not a bleb. The elevations are too smooth and the die doesn't appear particularly worn.
