(not actual coin, example use only) Could someone please provide me with the dimensions/weight tolerances for the 1868 aluminum Shield Nickel Proof? Internet searches reveal little more than what I was already aware of though there is a significant chance I am not looking in the correct place. Any and all information you feel relevant in determining authenticity or pertinent to properly identifying the coin would be appreciated as well. Thank you all in advance.
Are you looking for this sort of information: https://coins.ha.com/itm/patterns/1...ngc-r8-as-a-set-total-16-coins-/a/1181-6006.s Or this: https://coins.ha.com/itm/patterns/1...ow-r7-pr64-ngc-cac/a/1215-3444.s?type=NGC1215 Judd does not list the weight, but it does say that it was struck from normal dies - so dimensions should match a regular nickel. More importantly, if you're trying to authenticate one, it appears like all of the specimens I can find have the same die markers - the diagonal die scratches in the shield being the most obvious. Do you suspect that you have one?
In the 19th century, they made all sorts of trial and pattern strikes on all sorts of unusual metals. This coin was one piece of a 16 piece full mint set made in aluminum, made at the special request of the head of the Mint. It was intended to be a gift to a foreign mint, and a few extra sets were made. Read the Heritage auction above for more information about this particular set. A couple of the sets have been broken up, but that one remains in its original case. I got to see it at a show a few years ago, and it is simply spectacular.
For what it's worth, I find 8.92 for the specific gravity of the standard US nickel alloy, and 2.72 for aluminum. So, if the aluminum strikes have the same dimensions as the standard 5-gram nickel, they should weigh 5 * (2.72/8.92) = 1.525 g. If someone were trying to fake these, though, I'd think using the wrong metal would be their least likely mistake. You'd need to focus first on general appearance (are the design and lettering right), and next on die markers, as @physics-fan3.14 already suggested. A new example of this pattern would be big news. Please keep us posted!
I would never be so fortunate. However my brother recently discovered one that he described as being "too light to be real". He is bringing the coin with him this wednesday for a family function for me to inspect. Its not likely authentic, most likely a replica if it is indeed aluminum. However it's best to be aware of what I'm looking for in the coin.
I've never had the privilege to view a complete set in person. I'm only aware of three compete sets still in existence, but as for individual coins out there I am uncertain.
A couple of the sets were broken up, and if you read the Heritage auction above a couple of the sets are untraced presently. It is highly unlikely that a random person is going to find a coin like this, but I suppose its possible. Far, far more likely is that he has a counterfeit (modern or contemporary). A contemporary counterfeit would still be cool.
Indeed, it may be my final day. Thank you for the information. The ballpark weight will be most helpful.
Update: I was just informed by his oldest son that the coin was found recently in the 780lbs of silver coinage I gave him 23 years ago. I believe i may be ill. 2nd Update: My apologies. The above information is not correct. I confirmed this with my brother myself as I felt an urgent need to wake him from his slumber to verify this information. It was found in his wife's grandmother's belongings after her mother past away a number of months ago. The coin is being shipped today so hopefully by no later than Tuesday I will be able to share photos here with everyone. I will no doubt require a great deal of help. Ha ha
It was in 1886 that the electrolysis process of making aluminum from its ore became a reality. Before this, aluminum was one of the most expensive (if not THE most expensive) metals on earth.
I apologize for the lengthy wait concerning an update on the status of the coin. The culprit being personal health issues combined with my inability to properly identify the metal composition. The coin has since been identified as being a tin alloy containing trace amounts of copper, lead and silver. If I am correct in saying so this would indicate being made of a pewter alloy prior to 1970. Identification was indeed done by means of material being removed from the coins edge as I am sure some of you are fearing. Alas though the mystery has been solved it was done so at a cost greater than the value.
Thank you very much for the followup. I wonder what the best approach would be to determine whether it's a contemporary counterfeit, or even an off-metal pattern strike? (Don't know if any of those are known in pewter...)
