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Message:: [QUOTE="SPP Ottawa, post: 1538524, member: 39508"]I have been doing some research on Canadian "brown" 5-cent coins, 1982 to 1992, and while a majority of the ones I find are instantly recognizable as environmental damage, I am find a small population of nice, clean brown nickels that are in excess of 80% copper when I test on the XRF in my lab. The post-1981 Canadian 5-cent planchets are supposed to be 75% copper and 25% nickel (like the US ones). Planchet size and weight conforms to Royal Canadian Mint tolerances for the 5-cent coins - so I think they are the result of a copper-rich alloy mixing error (possibly procured from an external smelter). I published my results in the Canadian Numismatic Journal in June of 2012. I am now finding similar US 5-cent coins. Again, most are environmentally damaged, and within mint specifications (75% Cu / 25% Ni). But, then I find lustrous brown Liberty nickel with 81% copper and a brown buffalo nickel with almost 83% copper. Before I roll up my sleeves, and dive into a hunt of finding more US brown nickels and putting them under the XRF, are any of the US nickel error experts here able to tell me if there is published work already available on this subject matter?? My searches here, online in general, and in CONECA publications are coming up empty (exceptions to my searches are, of course, when nickels are struck on penny or foreign planchets - but that is not what I am talking about here).[/QUOTE]