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<p>[QUOTE=&quot;Publius2, post: 7666558, member: 105571&quot;]Well, I think verdigris is a catch-all term for copper corrosion in the form of copper carbonate and/or copper chloride.&nbsp; It can be just a thin greenish coating up to severe encrustations.&nbsp; Afflicts coinage of pure copper and it&#039;s alloys such as bronze.&nbsp; In general, silver and gold alloys of 10% copper don&#039;t seem to develop verdigris as we are used to recognizing it in copper and bronze coinage.</p><p><br /></p><p>Toning is a term that for numismatists is used universally for all coin metals; copper, bronze, silver, gold, nickel.&nbsp; Toning can be very slight but can proceed to what is called &quot;terminal toning&quot; which is usually considered an end state as far as numismatic value is concerned.&nbsp; Chemically it is not an end state but most collectors usually find terminal toning undesireable.&nbsp; For silver coinage terminal toning usually makes the coin quite black.&nbsp; Below is a half dime of mine that is pretty close to achieving a terminal state on the obverse.&nbsp; &nbsp; </p><p><br /></p><p>Also, toning as we use the term does not include encrustations, blisters and similar severe disruptions of the surface but rather a thinnish tarnish on the surface of the coin.</p><p><br /></p><p>The type of corrosion that is toning will depend on the alloy metals and the environment that is causing it.&nbsp; Like silver sulfide where the corrosive element is sulfur in the coin&#039;s environment.</p><p><br /></p><p>If I&#039;ve made any mis-statements, I&#039;d be happy to be corrected.</p><p><br /></p><p>[ATTACH=full]1317501[/ATTACH][/QUOTE]</p><p><br /></p>

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