I was confronted today with a off metal coin, I do not have pictures as the coin is not mine. It seemed legit ( no obvious signs of PMD or aulteration )but I´m trying to be carefull so I would like to ask some of you some quesitons. The coin is bronz but should be copper-Nickel. I smelled the coin and it had a strong metal oder (much more the normal) I actually have no idea why I did that could be somethign I read in a book Hehehe Now let´s say the coin is off metal would the weight be the same as copper-Nickel ? Best rgards Siggi
I have never had the chance to see or touch a off metal coin but from what I have read is that off metals normally weigh more or less depending on what type of metal was used. Other than that the only other way to find if it is a true off metal is to go and send it to any trusted coin grader and get it tested to see if it is off metal. Hopefully it helps a little, Jimmbob82
The weight should NOT match if its a true offmetal strike, unless somehow the two metals have the same SG. An offmetal strike was supposed to be identical to a regular strike in every way but the metal in the planchet. As an aside, these were done in the old days to trial a new die, striking it on softer metal so as to not wear the die out and still get "fresh" strikes in the correct metal later. Of course, later on they were sometimes struck for collectors. The only way I know is to die match it with a known good specimen, and rule out types of known copying. Sending it to be slabbed is good if you don't know how to do these things, (I am not claiming I do either). Chris
wouldnt that "damage" the coin by sinking it in something? even distilled water can cause certain metals to corrode or verdigris if im not mistaken
Unfortunately the weight and specific gravity will probably not help you much. Copper and nickel have almost identical specific gravity and therefor weight. (Copper SG is 8.96, nickel is 8.90) Then there is the question of what the exact composition of the alloys are. But for example in US coins the early copper coin had an SG of 8.96, the post 1864 cents (bronze) were 8.84, the brass 1963-1982 were 8.83. The copper nickel cents (88% copper 12% nickel) were 8.92 and the 75%copper 25% nickel five cent pieces are also 8.92 Obviously with SG's so similar, two blanks of the same size but different alloys will have the same weight to within the allowed mint tolerance. Not as long as they are completely dried afterward.....unless you manage to find some coins made of sodium.
