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<p>[QUOTE=&quot;dougsmit, post: 2255036, member: 19463&quot;]A few years back I was offered the opportunity to have some of my coins tested for metal by having a tiny hole drilled in the edge.&nbsp; I declined. Proper XRF will require having a spot polished on the edge so the reading would be coin not patina.&nbsp; I&#039;d decline.&nbsp; I do not accept any surface sampling method as valid because we know many coins were struck on flans prepared with acids (on purpose or just as a factor of handling).&nbsp; Surface enrichment and leeching of metals from burial conspire to make the surface different from the core.&nbsp; How significant is this?&nbsp; That would require a study comparing the surface results with fully destructive results on the same specimen.&nbsp; Not on my coins!&nbsp; When someone perfects a method of sampling subsurface composition remotely AND has demonstrated that the results do agree with destructive testing, we might consider it.&nbsp; As it is, I see numbers like 96.1 plus or minus 4.8 troublesome.&nbsp;&nbsp; Warren: As a statistician, can you explain the math here?&nbsp; Disclosure: I did not read the paper.[/QUOTE]</p><p><br /></p>

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