Planchet Errors Annealing Errors Improper Annealing?1964 D ((Improperly anniealed 5 cent nickle is this this the error everyone sees?))
IMO it looks more like environmental damage. As if it spent some time in the ground. Check this site: http://www.error-ref.com/improper-annealing/
After following link i noticed the 1992 showing same issues this picture here I have a 1992 P that looks odd here are a a few pictures of my coin.
IMO your coin does not look like the 1992 D you posted. (Taken from website that I gave the link for). On your 1964 You can see the CN color on the entire bust. And, as I said the rest of the coin looks like ED. Calling some experts: @Fred Weinberg; @mikediamond; @JCro57; @paddyman98: @Paddy54; @furryfrog02; et al.
Yep. Enviro damage, ground find. Looks like hundreds I've dug while detecting. Same with the '92-P coin.
I also say Environmental Damage to your Nickels. I Metal Detect. I have found hundreds of nickels just as yours that were exposed to the elements. Dirt, soil, sand, weather and chemicals will affect the Copper in the Cupro-Nickel Here are my examples - It also affects clad coins -
I will jump on the bandwagon since I was summoned lol. But it has already been answered. Your coin was sitting in the ground for quite awhile. Spender.
+10 It will take some time and research to understand the differences. On the surface (pun intended) they look "similar". But (for simplicity) one is corrosion and has the indications of corrosion (which varies with exposure, compounds exposed to, aging, etc), whereas the other is the state of the metal during the minting process.
I think this is environmental discoloration. Characteristics of an improperly annealed planchet include at least some remaining mint luster, and, in most cases, coin edges of a lighter, almost new coloration from where they scraped the collar upon ejection. Improper annealing leaves and oxide film on the coin, usually from an overheated furnace or from a film of oil which was on the planchet at the time of annealing. This coin shows neither of those characteristics.
Most of the black beauty nickels are 1958 and 1959 but there are other dates. Yours is rusted/ environmental damage. If the rim is the same color as the coin, it's not an annealing error. (I believe this is because after the planchets have been annealed and cooled, they go through a machine to upset the rim, before being minted. This makes the rim the brighter nickel color while the obv and rev are still darker from being improperly annealed. Please correct me if this is wrong.) There are a couple of threads here with excellent photos of true black beauties. I suggest you use the search box, bring up those threads, and read about it, and compare those photos to your coin.
Here are a few other pictures of dark nickles i found today. This a total curve ball why are the top coins of these images bellow allot smother finish and way shynier? Coins are same year but same mint but way diferent?
The top nickels in your photos are just less worn so they are in better condition. Some coins circulate heavily, others may sit in a coin jar for years, every one has a different history.