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<p>[QUOTE=&quot;akeady, post: 3380366, member: 83175&quot;]There are a few tests which use radio isotopes and could potentially be used on coins - certainly, there is a test which can determine when gold was last melted - it&#039;s based on (IIRC) small amounts of thorium in the gold which decays, releasing helium (alpha particles being helium nuclei), which is trapped in the gold.&nbsp;&nbsp; Analysis of the thorium vs helium ratio can tell how long since the gold was molten (when the helium would have escaped).</p><p><br /></p><p>Ah - here - Google knows all...</p><p><br /></p><p><a href="https://link.springer.com/article/10.1007/s13404-018-0238-z" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://link.springer.com/article/10.1007/s13404-018-0238-z" rel="nofollow">https://link.springer.com/article/10.1007/s13404-018-0238-z</a></p><p><br /></p><p>It&#039;s also true that modern steel made since atmospheric nuclear explosions began in 1945 is contaminated by radioactive isotopes, typically cobalt, so at least steel can be dated to pre-1945 and post-1945 and probably more accurately.&nbsp;&nbsp; Old battleships were an important source of such &quot;pre fallout&quot; of &quot;low-background&quot; steel, but of course ancient coins won&#039;t have been made from steel:</p><p><br /></p><p><a href="https://en.wikipedia.org/wiki/Low-background_steel" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://en.wikipedia.org/wiki/Low-background_steel" rel="nofollow">https://en.wikipedia.org/wiki/Low-background_steel</a></p><p><br /></p><p>ATB,</p><p>Aidan.[/QUOTE]</p><p><br /></p>

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