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<p>[QUOTE=&quot;calcol, post: 2786262, member: 77639&quot;]As Doug mentioned, checking physical characteristics of the metal won&#039;t distinguish genuine from fake coins cast or struck from the &quot;real stuff&quot;.&nbsp; Even sophisticated metal analysis, like XRF which gives a trace metal readout, won&#039;t work if original metal is used, e.g. striking fake 1889CC Morgans from metal obtained from cheaper, worn CC Morgans.&nbsp; So, physical characteristics are useful for detecting wrong-metal fakes only.</p><p><br /></p><p>Electrical characteristics, like resistance, capacitance, inductance, are among the worst physical measurements to use to evaluate the metals in coins for several reasons.&nbsp; As has been mentioned, these characteristics don&#039;t differ a lot among metals used in coins (copper, silver, nickel, gold, etc.), so very expensive test gear would be needed.&nbsp; It was also mentioned that the test leads have to have a very good attachment to the DUT (device under test aka coin), which means the oxide (or sulfide or carbonate or ...) layer has to be pierced.&nbsp; Tough to do that without damaging the coin.&nbsp; Finally, electrical characteristics are dependent on geometry.&nbsp; The resistance of a coin in the 6-12 digit accuracy needed to distinguish metallic composition would be influenced by seemingly minor variations in surface contamination, wear, strike, diameter and thickness.&nbsp; Positioning of the test leads would be critical too.</p><p><br /></p><p>Variation in distribution of metals within a coin would affect resistance even if the overall composition was identical.&nbsp; As an extreme example, imagine two coins that are 90% copper and 10% silver.&nbsp; In one coin, the silver is all in a disc in the middle.&nbsp; In the other coin, the silver is all in a ring that runs around the periphery of the coin.&nbsp; If you attach the test leads to the edges of the coins, the resistance of the latter coin would measure less than the former.</p><p><br /></p><p>Better physical methods for metal analysis range from the simple like specific gravity and magnetic characteristics to sophisticated like XRF, ultrasound transmission, x-ray / gamma-ray absorption, etc.</p><p><br /></p><p>Cal[/QUOTE]</p><p><br /></p>

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