Silver coin sources can be localized!

[delta]

Due to differences in silver isotype composition, and the presence of alloyed metals and/or impurities, it is now fairly easy to determine the geographic source of the silver in a coin. This can be historically significant. Here are some results from a survey of Spanish coins from the centuries immediately following the conquests in Mexico and Peru:

 

Link to science article.

 

I'm a lot more impressed by the methodology than the stated conclusions, which leave me unconvinced. The sample population was too small, only 91 coins over several centuries, and we are not informed how the samples were chosen.

 

[shirohniichan]

Interesting!

[Coindude]

It's pretty much the same thing they do to track down nuclear devices. It all has to do with the isotopic distribution. I guess I never thought of it being used for coins that way, but it makes sense.

[shirohniichan]

While it wouldn't be "worth it" (in terms of increasing a coin's value), I'd love to track which coins struck from eastern California silver. There were a number of silver boomlets all along the east side of the Sierra Nevada and even down to the Mojave (Calico, Providence, and other ghost towns were silver boom towns at one time).

 

Was silver from Benton used in US trade dollars? How about silver coins struck from silver mined in Cerro Gordo? Inquiring minds want to know.

[Conder101]

I've seen research like this before being used to trace the source of copper in early US state coinage and the counterfeit British halfpence. I have seen it for tracing copper sources of the early US cents and some British coinage. This kind of research is interesting but it has it's limits. Metals are commonly recycled and when it is the resulting melt comes from many sources. This will make tracing isotope ratios back to the mine source much more difficult and after several recycle/melts impossible. So these tests really only have validity on coins produced from virgin melts.

 

I also see some odd things in the article.

 

Silver coins minted in the Americas and those produced in European mints are therefore indistinguishable to the naked eye.

 

They are? You might try looking at the differences in styling and most importantly the mintmarks. If they mean that silver from America looks like silver from Europe all I can say is Duh.

 

The researchers firstly demonstrated that Andean and Mexican coinage dating from before 1492 has three distinct isotopic compositions.

 

Where did they come up with Andean and Mexican coins from before 1492?? The first coins struck in the New World didn't happen until around 1526. But they somehow used coins from before the Europeans arrived.

 

During the 1500's there wasn't a lot of treasure flowing back to Spain. I don't believe the flow of silver started to become significant until the 1600's and not really heavy until after the mid 1600's. So basically they have confirmed what could have been learned by reading the manifests of the ships coming back to Spain.

[TomB]

Similar techniques were used when Tylenol capsules were deliberately poisoned in the late 1970s or early 1980s.