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Message:: [QUOTE="Colonialjohn, post: 7637674, member: 57741"]This Mathur paper is interesting - Mathur KNEW before hand the copper sources were DIFFERENT based on U.S. Mint historical records. Records exist for this time period in the mid-1800's or so as we transitioned from English to American copper sources. No records EXIST for the 18thC for U.S. Colonials but its logical to assume if we were using Cornish copper up to the mid-19thC for copper cents it was a primary source before this time. Simsbury was an exception since the Cu PURITY of this mine was WORLD RENOWNED for its purity so it was worth exporting/refining and then returning this Cu back to the Colonies. Back to the paper - Since he knew the sources were already different he just verified this with Cu isotopic analysis just to get a benchmark data set for these copper sources which did show DIFFERENT Cu isotopic fractionations. Its the beginning ... as more data is gathered/compared/stockpiled almost all copper pieces will have confirmed or almost confirmed provenances in the future for U.S. coinage. It will just take decades ... not years. JPL[/QUOTE]