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<p>[QUOTE=&quot;Oldhoopster, post: 3248713, member: 84179&quot;]I believe that [USER=27832]@-jeffB[/USER] generally has the right idea. I would expect a post mint zinc plated cent to have a copper/zinc composition like you see.&nbsp; The Xrays do penetrate slightly below the surface of the sample (depends on the material but it is deeper than normal plating thicknesses).&nbsp; So your results show the zinc the post mint plating and is also picking up the copper plating layer in the original planchet below it (and some of the Zn may also the original zinc blank, but can&#039;t say for sure and isn&#039;t that important to this discussion)</p><p><br /></p><p>I wouldn&#039;t get hung up on the trace elements like Nickel and Iridium.&nbsp; They could be junk in the plating bath or electrodes, but IMO, they are just errors in the algorithm used by the machine to calculate the results. </p><p><br /></p><p>If you look at your picture of the readout screen in post #8, notice the graph above the composition readout. Based on the energies and heights of the peaks, the machine calculates the specific elements and amounts. It has Sn (tin), I (iodine), and Ag (silver) over some of the small peaks but these don&#039;t show up in the compositional analysis.&nbsp; Trace level elements can be hard to accurately tease out of the noise and I&#039;m sure the manufacturers of the handheld units are more concerned with their equipment detecting precious metals correctly than determining exotic trace elements. </p><p><br /></p><p>Maybe the mint got ahold of some of the meteorite that caused the dinosaur extinction at the Cretaceous-Tertiary boundary event (it was high in iridium) to make some experimental planchets, but more than likely, you just have a normal cent that was zinc plated after it left the mint[/QUOTE]</p><p><br /></p>

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