It's a strike-through error, but I can't establish the identity of the obstructing material with any certainty. It could be "grease", since cooked lubricant can get hard and brittle and, when breaking up, create indentations with sharply defined borders. At any rate, it's not worth slabbing. It's value would would probably be no more than $25.
Well that's all I wanted to hear that the object is an uncertainty, and not a definitive observation on the foriegn object that struck this coin. JCFormerly Jazzcoins Joe
Also the stuff we refer to as "grease" is usually not just a homogeneous semi-liquid like axle grease, it can be heavy grease, lubricating oils, plus dirt, dust, metal shavings and possibly even chips off a die all stuck together. Semi-liquid crud would probably be a better term for it, but grease is easier to say.
Cool Half! Good find. But looking at the planchet, it appears to have horizontal lines on it. Have you compared the thickness to others?
I was thinking if it were a capped die error wouldn't the rim also show some evidence of this ...the rim is crisp....I vote it was a half eaten tootsie roll that mades it way into the minting process