I know what it is... I am interested in the how or why it exists. Is it a slight misalignment of the collar and the die that causes finning?
Many different striking errors can create a double rim effect. When overall striking pressure is too high, or if striking pressure is increased at one pole due to die tilt, coin metal squeezes into the narrow gap between die neck and collar, leaving the coin with a thin vertical flange that is called a “fin.” Not my words Randy but hope this copy & paste helps.
Well, all you are going to get out of me is that a fish has fins. But I’m going to read about it now!
I looked online to read about it and this came up and saw his collection. http://www.error-ref.com/?s=Finned+rim His look better. Lol. I do have some but I always thought of it as MAD. Ty for the lesson.
@Randy Abercrombie My thread from my birthday Feb 9th, 2017 Finned Rim Explained - 6000th Post | Coin Talk
This was posted recently. Good photos of finning. https://www.cointalk.com/threads/la...-oz-marine-silver-medal.403818/#post-23260585
Sometimes the fins will break off of the struck coin when it is ejected from the collar die and will become a strike through in a following struck coin.
Oh dear, I can see it now: Woman sues U.S. Mint for cutting herself with a finned coin Just my sick humor, forgive me please.
Here is the largest fin I have ever seen on a coin, token or medal. This is one of those fancy Civil War tokens that were was made for collectors. It was struck on a gold filled planchet. The Fuld patriotic die variety numbers are 129/349. Here is the token. And here is the fin. Obviously, this piece was never intended to be used in circulation.
Perhaps the most famous "fin" of all is the 1907 High Relief $20 gold with the "wire rim." It seems be the most common variation for that "trophy coin." Check out the left side of this one.
