Message:

<p>[QUOTE=&quot;2manybooks, post: 9784969, member: 8267&quot;]Lead does corrode, as can older pewter that contained lead. (Modern pewter is composed primarily of tin, plus some antimony and copper.) </p><p><br /></p><p>Depending on conditions, lead can form a patina of lead oxide, which is dark gray and mostly protective (meaning it inhibits further corrosion). Most lead corrosion products are white, (primarily forms of lead carbonate). But exposure to organic acids can produce a corrosion layer that sounds similar to what you say you found on the amulet. Described as &quot;a thick, porous layer of dark grey, powdery corrosion products&quot;, such deterioration has been observed on lead artifacts stored in wooden cabinets for a long period of time.</p><p><br /></p><p>Here are some examples of corroded lead objects, taken from <u>Corrosion degradation of archaeological lead: A review and case study</u>, by A. Towarek et al., National Museum of Warsaw -</p><p><br /></p><p>[ATTACH=full]484268[/ATTACH]</p><p><a href="https://deliverypdf.ssrn.com/delivery.php?ID=113078126115092093126095100003107027035089005085064035004028017059115117053087080008083065091089031014004088016082004027098126102031067027119041092104056103109075085090111025024073009123111107050057096111063033095008025125117070124120121126114074086007100068095007097029095028072120082105110&amp;EXT=pdf&amp;INDEX=TRUE" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://deliverypdf.ssrn.com/delivery.php?ID=113078126115092093126095100003107027035089005085064035004028017059115117053087080008083065091089031014004088016082004027098126102031067027119041092104056103109075085090111025024073009123111107050057096111063033095008025125117070124120121126114074086007100068095007097029095028072120082105110&amp;EXT=pdf&amp;INDEX=TRUE" rel="nofollow">https://deliverypdf.ssrn.com/delivery.php?ID=113078126115092093126095100003107027035089005085064035004028017059115117053087080008083065091089031014004088016082004027098126102031067027119041092104056103109075085090111025024073009123111107050057096111063033095008025125117070124120121126114074086007100068095007097029095028072120082105110&amp;EXT=pdf&amp;INDEX=TRUE</a></p><p><br /></p><p>Corrosion products can often provide information about an object&#039;s history, and what environments it has been subjected to.</p><p><br /></p><p>Recently, a technique has been devised for directly dating lead objects recovered from archeological contexts by measuring the corrosion content -</p><p><br /></p><p>&quot;Meissner fraction in the superconducting state of lead archaeological artifacts is used to evaluate the mass of the uncorroded metal in the sample. Knowing the total mass of the sample, the mass of all corrosion products is established. It is shown that this mass correlates with the archaeological age of the lead artifacts over a time span of ∼2500 years. Well-dated untreated lead samples from Tel-Dor, the Persian period, Caesarea, the Byzantine and the Crusader periods as well as contemporary data were used to establish the dating correlation. This new chemical dating method is apparently applicable to lead artifacts buried in soils with pH &gt; 6.5. In such soils the corrosion process is very slow and the corrosion products, mainly PbO and PbCO3, accumulate over hundreds of years. The method presented is in principle non-destructive.&quot;</p><p><a href="https://iopscience.iop.org/article/10.1088/1367-2630/5/1/399" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://iopscience.iop.org/article/10.1088/1367-2630/5/1/399" rel="nofollow">https://iopscience.iop.org/article/10.1088/1367-2630/5/1/399</a></p><p><br /></p><p>As for the subject of the amulet, the most informative passage I have found is included an article by Frances and James Schwartz, &quot;ENGRAVED GEMS IN THE COLLECTION OF THE AMERICAN NUMISMATIC SOCIETY: 1. ANCIENT MAGICAL AMULETS&quot;, published in <span style="color: #000000"><a href="https://www.jstor.org/journal/musenoteamernumi" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.jstor.org/journal/musenoteamernumi" rel="nofollow">Museum Notes (American Numismatic Society)</a>,</span> Vol. 24 (1979), pp. 149-197.</p><p><br /></p><p>[ATTACH=full]484273[/ATTACH]</p><p><a href="https://www.jstor.org/stable/43573582" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.jstor.org/stable/43573582" rel="nofollow">https://www.jstor.org/stable/43573582</a>[/QUOTE]</p><p><br /></p>

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in