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<p>[QUOTE=&quot;Colonialjohn, post: 7637631, member: 57741&quot;]Mathur etal.(2009b) demonstratedthat US cents from the nineteenth and twentieth centuryshifted from imported Cornwall ores and Michigan ores tothe use of highly variable porphyry copper deposits around1880. Silver-based coins dating from the fourth century BC until the eighteenth century AD were analyzed by Desaultyetal. (2011), and it was demonstrated that European silvercan be distinguished from Mexican and Andean sources by a combination of Pb, Ag, and Cu isotopes. Balliana et al.(2013) investigated Roman bronzes from Northern Spain for Sn and Cu isotopes. A few analyses were undertaken on cop- per artifacts from the Old Copper Culture and compared to the native copper occurrences in Michigan (Mathur et al. 2014).In terms of wider usage of Cu isotopes in archaeometry, tur-quoise(Hulletal.2008)andglass(Loboetal.2014)werealsoanalyzed for their Cu isotopes to test the applicability for&nbsp; provenancing these materials.To sum up, the Pb isotope signature is specific for theidentification to deposits, while the Cu isotope signature isspecific to the identification of ore mineral sources withinthe deposit. In the ideal case, the combination of Pb and Cuisotopes from an artifact would not only provide informationabout the provenance but also about the type of ore used inancient times. Thus, conclusions can be made about the depthofthe miningactivitiesinancient times,evenifall tracesweredestroyed by later mining activities. The shift from colorfuloxidizedoresnearthesurfacetosulfidicoresatagreaterdepthof the same deposit would have required substantial developments in winning methods, e.g., hauling, mine draining, and timbering to support deeperadits. In addition,the extractionof copper from sulfidic ores, especially chalcopyrite, in comparison to oxidized ores requires advancements in the techniques of smelting. Preceding roasting of the ores can be postulated.Thus, the use of sulfidic ores is linked with changes in thetechniques of exploitation and smelting, resulting in the fact that the identification of ore types used in prehistoric times is of substantial interest.</p><p><br /></p><p>Mathur R, Titley S, Hart G, Wilson M, Davignon M, Zlatos C (2009b)The history of the United States cent revealed through copper iso-tope fractionation. J Archaeol Sci 36:430</p><p>&nbsp;–</p><p>433. doi:<a href="http://dx.doi.org/10.1016/j.jas.2008.09.029" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://dx.doi.org/10.1016/j.jas.2008.09.029" rel="nofollow">10.1016/j. jas.2008.09.029</a>[/QUOTE]</p><p><br /></p>

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