Very nice find and congratulations! It was Struck Through Grease, and it was a lot of it! Definitely a keeper. http://www.error-ref.com/struck-thr...-grease-oil/
It's very common. It happens a lot, so there would be no premium for them. They're called Broken Die Posts. Click on this link, and scroll down to Coop's helpful explanation. http://goccf.com/t/325561
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Also off topic just a general question how common are filled in mint marks and is there value in them?
Also off topic just a general question how common are filled in mint marks and is there value in them?
It's very common. It happens a lot, so there would be no premium for them. They're called Broken Die Posts. Click on this link, and scroll down to Coop's helpful explanation. http://goccf.com/t/325561
Errers and Varietys.




















