If it is a depression: Struck thru or lamination (sharp edges). If it is raised: gunk on coin's surface.
Not necessarily! Grease and debris often gets compacted in the recesses of the devices and then drops out onto the surface of the planchet where it is then impressed before falling away. The image appears to be recessed, so I believe that it is a strikethrough. Chris
The edges are way too sharp for it to be grease. Yes, grease would cause it to be incuse. And yes, it can be a blob. But they don't have sharp edges. I doubt it is a strike through because it obstructed only part of 3 letters, going into the die, leaving the letter in tact but left no traces behind. Is that possible? Well, maybe, but very unlikely.
I have to disagree with you. I found hundreds of similar examples just searching one $50 Mint bag. A few examples even retained parts of the strikethroughs. The grease and minute particles of dust and debris are compacted together from continuous strikes, and the outer edges can be thinly tapered so the letters show through when it is struck into the planchet. In other places, the compacted amalgam can be thicker resulting in an apparent drop-off. This thickest build-up probably came from the outer recess of Lincoln's head or hair, and the tapered edge (over the letters) from the innermost recess of the head. Chris
Lincoln had a little lam, it's field was full of holes. And everywhere that penny went, he was never again to be rolled
Another toothpick trick @Insider? Really? Stby... The anomaly is definitely a depression/recess in the coin. Not raised. Yes, the edges appear to be sharp. Here a a couple more pics. Not sure if they will help.