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<p>[QUOTE=&quot;Colonialjohn, post: 2124247, member: 57741&quot;]As maybe some of you know I have been using XRF and SEM/EDS analysis for several years now - I do like some of the comments and that rainbow chart - IS&nbsp; KOOL - I still believe this topic is trivial - as I think we are years away from determing methods of AT &amp; NT using surface material analysis and since the average NGC grader it seems looks at a coin for about 60s and does not use a stereo microscope, etc.</p><p>&nbsp;</p><p>However - since we are on page 22 and we are still going in circles I will just throw some tid-bits out there:</p><p>&nbsp;</p><p>1. I have confirmed by SEM/EDS that sufur and chlorine (compounds) are the two most common elements found on a coin surface. As you may know and with my new book on contemporary circulating counterfeits I use these tools simply to determine alloys and PREDICT the age of a counterfeit (i.e., modern forgery vs. period-circulating).</p><p>2. From (1) I absolutely confirm W. Weimer&#039;s simplistic coin chemistry findings of sulfur and chlorine being the two most common contaminants found on a surface.</p><p>3. When I was big in U.S. Colonials I did come across some great rarities that went into my collection. Let me use this one example. This coin was a NJ Maris 10-G ($5,000-7,500). The coin was orange surfaced cleaned from a previous pedigree. It was stripped down (don&#039;t ask) and then sulfur ointment was placed in an envelope. The coin sat there for almost a decade in this paper coin envelope. It came back say 50% naturally toned copper - so to speak.</p><p>4. Just like in our GNL book on Counterfeit 8 Reales certain trace elements in an alloy do not dicate a 18thC forgery but a modern Chinese forgery or 20thC copy. So future researchers can if they wish explore the surface of a coin surface and look for elements that should not be there say that are remnants of a toning product - however realize that whether someone adds sulfur to a coin&#039;s surface or into a flip as I did to try to revive this great rarity that someone harshly cleaned - the compounds of copper and sulfur are probably the same whether from the atmosphere or from a sulfur hair product. However using an SEM or high magnification it may be possible to look at a surface IMO and determine if its natural or if chemical agents were used based on residues, etc.. As someone has indicated I have never seen Material Analysis used for such a study.</p><p>5. My new book (Forgotten Coins of the North American Colonies - Revisited) due out in 2017 will go into greater details but not on toning but how to spot Chinese fakes based on their alloy make-up&#039;s etc..</p><p>&nbsp;</p><p>Questions - but can you make them SCIENTIFIC? Please ...</p><p>&nbsp;</p><p>John Lorenzo</p><p>Numsimatist</p><p>United States[/QUOTE]</p><p><br /></p>

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