Not really worried about any value, just trying to figure out how these came to be. The first cent looks like a crumpled aluminum can, but the printing is still sharp, not stressed. The rim is still round and flat, only the interior of the coin shows any bending. I don't think this could be done in a vise, even with heat. Side shows layers and a small flaw. hmmmm Now this next one has me stumped. Silver-grey, nice finish, appears to be zinc. I've read most the post I could find about zinc cents, but still couldn't find any answers. Most dealt with acid dipping to reveal the zinc core. But this being a 77 and supposed to be 95% Copper, so the next thought would be plated. I do need a better scale, but I believe it to be the same as a normal copper cent 3.11 grams. The small flaw/nick seems to show the inner metal to be the same composition as the outside of the coin. Guess I could give it another scratch somewhere to see, but I'd rather not. Any thoughts? Would ncg give this the time of day, or just auto-body bag it?
On the first one, my first impression is post-mint, but the design elements are so well preserved that it bears further investigation. The second coin looks the same color as a cent that has been heated.
Since this one is a 1991D, we know that it should be copper-coated zinc. Because of their vastly different melting points, with copper at 1085 C and zinc at 420 C, it is possible to heat it to say 500 C and have a liquid inner zinc core and a thin solid copper outer shell. Now imagine just bumping it with something- the copper deforms and the zinc flows. Upon cooling, it would look like the cent you have. I think this is what happened mainly because all the details of Lincoln's face are still on the "dented" parts whereas if it were a problem with the planchet before being struck it would not have struck normally. You're correct about the weight and it being a 95% copper cent- there is a common chemistry demonstration that takes a copper cent and coats it in a thin layer of zinc to make "silver pennies". The next (optional) step is to put it in a bunsen burner and let the thin surface layer of zinc mix with copper to make brass, thus creating "gold pennies". Bottom line, in my opinion both have been experimented on and are neat finds, just not something to send in as a true mint error.
Thank you for the great explanations. Just what I needed so I can put these two to rest. Actually, taking the 77 on to that third step sounds kinda fun, I may have to give that a try.
there's a third possibility that the coin was dipped into a 500 deg solder pot or place a solder iron and apply a resin core solder to it till it is tinned completely. I have done this to several cents when work was slow, it also removes the green oxidation from the coins.
I think 500 deg. would remove any foreign material. You work around metal plating and coating I presume. Good post tdm. Rhubarb
good guese but no. i used to work in electronics, soldering stuff. i would suggest that washing ones hands after handaling that coin if it was tinned. solder is a mixture of 50% or 63% lead and the balance is tin.
