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Message:: [QUOTE="otlichnik, post: 5944074, member: 109731"]It doesn't take much iron (or, less likely in ancients, nickel) for a coin to respond to a magnet, especially a powerful magnet. It is quite common among Chinese and other Asian cash and can be used to help attribute to mints.  For example, Wang, Cowell, Cribb and Bowman's paper Metallurgical Analysis of Chinese Coins at the British Museum, notes (p.1) "Both the yuan coins and the 150 BC banliang coins contain traces of lead, tin and iron, consistent with them being made from the first refining of copper ores, suggesting that they were probably made close to the mines from which the ore was extracted. A distinctive characteristic of these coins is that the small amount of iron in them renders the coins susceptible to a magnet." It is likely that late Roman bronze coins, especially in periods of very high volume minting, would have used the cheapest materials available - and thus any "new" copper was likely the product of minimal processing - i.e. one refining cycle - and thus contained elevated Fe levels when compared to more refined products. SC[/QUOTE]