Halve dollar error? Please advise

[rfishoutofwater]

Picked this up from a teller tray at my pick up bank a little bit ago. Still on a high from my silver score earlier. Had to pick up some dimes, nickel and pennies. Anyhow this was in the teller tray. Looks like a mint error. What do you all think?

 

[rfishoutofwater]

Here are some pictures

 

[Wickaboag]

I'm not well versed in errors, but it (could) be a "greaser."
They put grease on the coin machines, and sometimes it smudges the coins some I guess.
Maybe it's worth mega bucks!
WIcka

 

[rfishoutofwater]

i was thinking a grease die error

 

[cooper36]

Not sure hope it is and worth a fortune.

 

[sagittarius98]

Greased die, you can sell it on eBay for a few dollars, but no coin shop would buy it.