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<p>[QUOTE=&quot;l.cutler, post: 2970748, member: 13318&quot;]Syd Martin&#039;s book on the Rosa Americana coins has a section on metallurgical tests done on sample coins to determine composition as well as the frequently seen bubbling.&nbsp; The coins were all found to be much higher in zinc than they were purported to be and there was no trace of silver. There was also traces of lead in the coins.&nbsp; The coins were made on cast blanks instead of cold rolled as the Hibernias were, causing the grain structure to be different and making the coins brittle.&nbsp; The bubbling was found to be caused by corrosion or dezincification of the copper zinc coins.&nbsp; The corrosion seems to have been caused by a high sulfur content in the coins, most likely from the molds used to cast the blanks.&nbsp; The bubbling could have appeared as soon as a few months after coining.&nbsp; This is a very simplified version of the metallurgy described in the book, but it is the basics of it.[/QUOTE]</p><p><br /></p>

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