I am about to do some elemental analysis of some copper coins
(English George III halfpence). I trying to figure out what to use
as standards. I expect a high likelihood of finding (in addition to
copper) minor amounts of tin, zinc, arsenic, antimony, silver, and/or
gold. But I'm not sure about indium, nickel, cobalt, and iron.
Does anyone have experience or references on 18th century English
copper?
Related to the question of what I might find is what standards to
use. Any thoughts are appreciated. The first phase of the work will
be with neutron activation analysis (I can irradiate a small group
for pilot work in the next week at the University of Michigan's
reactor, but would consider trying again later if I need standards we
don't have or can't get quickly). I hope to reanalyze the same set
of coins with an WDXRF microprobe and possibly laser ablation ICP-MS.
Some of the questions I'm looking at will be comparisons of regal
coins and counterfeits to see if counterfeits vary in metal quality
as well as generally being lightweight (not all of them are!). Also
tyring to see whether counterfeits made in America can be
distinguished metallurgically. A few varieties can be identified as
American but for most varieties origin cannot be determined yet. I
hope to also look at some related issues definitely made in the U.S.
in the 1780s to see if any were made with American copper.
Any thoughts or references would be welcome.
Thanks,
Dan Freidus
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