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Determining the origin of gold and silver in early US coins
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68 posts in this topic

Technology of elemental XRF analysis ppresents an indirect method for determining the place or country of origin for the gold and silver used in early US coins.

Refining by US and European Mints was somewhat inefficient and normally incomplete. Trace elements found in native gold and silver ores were often retained in the final coinage products, and these allow us potentially match elemental signatures of mineral specimens mined from known locations to coins created with those metals. For early US coins we have a situation where nearly all gold and silver was obtained by melting melting foreign coins (sometimes bullion) and then adjusting the fineness to US standards.

Therefore it is possible to show that during a certain month of coinage at Philadelphia, the gold came from melted 8 Escudos and that in another month the gold origin was English. This could also help us identify when American gold from the Southern Gold Fields first gained use in American coins. Much the same could be done with silver, possibly to the point of establishing the proportions of silver used that originated from different Spanish mints.

Given the rarity of these early US coins, the logical place to make measurements at at authentication company facilities. XRF nondestructive elemental testing could be incorporated as a routine, in-house authentication step. The data would, after several years, begin to accumulate to the point where similar data sets could be obtained from European, South American, African and Caribbean sources. Elemental analysis matching to location of origin could then begin -- hopefully as a cooperative international endeavor.

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I think it would be making a large assumption that the melts used were from similar coins that used ore from specific mines.  I suppose with enough data you could tease out the stats, but initially, I think it would be tough to get meaningful data, especially with the European recycling of bars, and coins

That being said, I think it would be easier to get something on when Southern gold was first used, of CA gold was used at the southern mints.  But to say that the gold from a 1797 Eagle came from Mexico may be difficult

XRF would be the way to go in my opinion, but I believe lab instruments would have less variability for trace elements than a hand held units, and it's the trace elements that will give you information.  That also assumes the refining method(s) didn't introduce variability

Great idea for a project, and the data would be fantastic, I just think it would be difficult

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Isn't this one of the reasons that coins struck in San Fran differed from Denver and especially Philly ?  Plus the differences in equipment, tolerance levels, etc.

Add in differences in the dies and then you have "poorly struck" and well-struck coins....lustrous ones and non-lustrous, etc.

Biggest difference would probably be between the 1908-S (in top condition one of the best-looking Saints) and the 1908 NM which is very blah-looking. :)

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Lab grade equipment would be required - but the major TPGs have access to this.

I agree that it would be difficult to analyze the European gold component and that considerable data is required to get the statistical parameters well established. Internal trade patterns would help, and some European countries have metal samples going back hundreds of years. It's clearly a long term project requiring patience and consistency -- but we cannot predict what might suddenly pop-up, either.

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Just on off hand thought, but I think a lot would depend on where the ore was refined, the consistency of the process, and whether there are trace elements specific to GA/NC that won't get confounded by refined ores that might be mixed into the melt.  

I still would love to see a project like this succeed. It would be a big contribution to the body of knowledge. 

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On 3/23/2022 at 4:37 PM, RWB said:

It would be interesting to be able to pinpoint the earliest use of Carolina or Georgia gold in US coins.

Is that difficult ?  I would think we would know when those mines were opened and when they shipped to the Mints near them, some of which closed.

Edited by GoldFinger1969
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We actually know little about when US gold was first used for US coins, or even available. Documents and archives describe early discoveries, and some gold samples exist in the SI geological and ore collection (some from the old Mint Cabinet). I am not aware of anyone actually doing the data collection and measurements. But it is common for each gold or silver vein (or even placer run) to have its individual trace elements.

The earliest Carolina and Georgia gold was all placer, so there were not real "mines" until the 1830s

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On 3/23/2022 at 8:10 PM, RWB said:

We actually know little about when US gold was first used for US coins, or even available. Documents and archives describe early discoveries, and some gold samples exist in the SI geological and ore collection (some from the old Mint Cabinet). I am not aware of anyone actually doing the data collection and measurements. But it is common for each gold or silver vein (or even placer run) to have its individual trace elements.  The earliest Carolina and Georgia gold was all placer, so there were not real "mines" until the 1830s

In theory...if gold today (not sure about 100-150 years ago) was purified to 90% or 99.9% purity.....shouldn't it look the same if you struck a coin on the same mint dies ?  Or is there a real atomic or chemical difference between gold ore processed in California vs. Dahlonega and other places on the East Coast ?

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On 3/23/2022 at 3:37 PM, RWB said:

It would be interesting to be able to pinpoint the earliest use of Carolina or Georgia gold in US coins.

:)

Weren’t most of the Charlotte and Dahlonega coins from local finds?

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On 3/23/2022 at 5:59 PM, Oldhoopster said:

Just on off hand thought, but I think a lot would depend on where the ore was refined, the consistency of the process, and whether there are trace elements specific to GA/NC that won't get confounded by refined ores that might be mixed into the melt.  

I still would love to see a project like this succeed. It would be a big contribution to the body of knowledge. 

....would be interesting from a curiosity point, possibly usable data for various research or historical articles or projects, not sure just how much it would contribute to the collecting aspect of coins...nor how much of a demand for such data would materialize, prob the biggest question would be who would pay for the added expense, certainly not the average collector....decent endeavor for some doctorial candidate if could convince a tpg to co-sponsor....as for adding to the hobby minimal interest....

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On 3/23/2022 at 10:34 PM, zadok said:

....would be interesting from a curiosity point, possibly usable data for various research or historical articles or projects, not sure just how much it would contribute to the collecting aspect of coins...nor how much of a demand for such data would materialize, prob the biggest question would be who would pay for the added expense, certainly not the average collector....decent endeavor for some doctorial candidate if could convince a tpg to co-sponsor....as for adding to the hobby minimal interest....

If you're into the hobby for collecting/investing then I agree, but if your interesting is the history behind the coins, how/why they were made, how they moved through commerce, and how contemporary people used them for daily transactions, then research like this is fantastic.

The cost and access to samples could be a formidable barrier, however.  But it can't hurt to hope.  There are some studies tracing ancient coins to mine sources that I found very interesting (I don't have the sources handy.  Sorry)

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On 3/23/2022 at 10:51 PM, Oldhoopster said:

If you're into the hobby for collecting/investing then I agree, but if your interesting is the history behind the coins, how/why they were made, how they moved through commerce, and how contemporary people used them for daily transactions, then research like this is fantastic.

The cost and access to samples could be a formidable barrier, however.  But it can't hurt to hope.  There are some studies tracing ancient coins to mine sources that I found very interesting (I don't have the sources handy.  Sorry)

...interesting most definitely, fantastic?...but obviously any credible info cant hurt...yes i have read bout the sources for ores used in several of the ancient series, mining activities for both roman n greek sources come to mind.....the D n C gold issues would seem to offer the best avenues for uncorrupted sourcing....

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This is of interest to many/most, but for most coins it's basically a short 1-liner or 1-paragraph.  I'm not sure how expansive tracking the source, content, and quality of the gold/silver would be to a coin holder decades later.

I think the HISTORY of the coins and what they went through over the decades is much more interesting, makes for better storytelling, etc.

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On 3/23/2022 at 10:37 PM, GoldFinger1969 said:

This is of interest to many/most, but for most coins it's basically a short 1-liner or 1-paragraph.  I'm not sure how expansive tracking the source, content, and quality of the gold/silver would be to a coin holder decades later.

I think the HISTORY of the coins and what they went through over the decades is much more interesting, makes for better storytelling, etc.

Very much of the early Philadelphia struck gold came from foreign coin being remelted, formed, and struck as U.S. coinage. This data project would be especially useful for Philadelphia coins. The branch mints, remember, were established specifically for localized metal finds. The percentage of re-coining at the branch mints is unlikely to be much at all, but the Philadelphia, and to a slightly lesser extent New Orleans, might prove very interesting. 

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Refining techniques in the late 18th and early 19th century were poor when compared to improved processes after mid-century. That left trace elements which can be used to identify the source of the gold or silver.

The actual cost of collecting data would be small if we assume the authentication companies do the XRF on every early gold and silver coin submitted as a part of normal workflow. The raw data would merely be a table of dates, denominations, XRF results, and date of the test/equipment used. There would be no ownership or organized acquisition of specimens. (Note: XRF analysis can be performed through hard plastic using correct techniques. But the handheld units are not consistent enough for good results.)

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On 3/24/2022 at 11:44 AM, RWB said:

What I've suggested is a scientific study about knowledge, not coin variety or "value" in money.

It'd be of interest...but of more interest would be hearing how guys like Paul Wittlin found the overseas hoards that they repatriated. 

Did they talk to bank executives...private bankers....the holders of the coins themselves......did the bank contacts accumulate the coins into a sufficient number or did they literally dribble out 1 or 2 or 3 coins....did bags of DEs remain untouched and unmoved for decades or did they get moved more frequently....was anybody else but American numismatic representatives interested in these coins....etc.

Some of this is covered in your book but since many of the principals are decesased it's no longer possible to directly interview them which means we need to research it from scratch.

Edited by GoldFinger1969
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On 3/24/2022 at 10:42 AM, RWB said:

Refining techniques in the late 18th and early 19th century were poor when compared to improved processes after mid-century. That left trace elements which can be used to identify the source of the gold or silver.

The actual cost of collecting data would be small if we assume the authentication companies do the XRF on every early gold and silver coin submitted as a part of normal workflow. The raw data would merely be a table of dates, denominations, XRF results, and date of the test/equipment used. There would be no ownership or organized acquisition of specimens. (Note: XRF analysis can be performed through hard plastic using correct techniques. But the handheld units are not consistent enough for good results.)

I am not versed on the finer points of XRF use. I have a couple of questions. Is XRF used routinely by the TPGS? Is it in any way costly to do, including costs in time? What is the capital equipment cost to set up a useful XRF setup?

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A lower-end lab grade XRF runs about $15k. Like any precision instrument, it must be properly maintained, calibrated and used by people who understand what they are doing AND understand how to interpret the raw results. The hand held units, especially ones run by jewelers are rarely correctly calibrated, cleaned, or otherwise maintained, and the operators are only slightly more knowledgeable that some phony ambulance chaser.

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Typically, NGC performs this work only when necessary to determine composition, as with many pattern coins, mint errors, etc. It will perform this work at a customer's request for a fee. It used to be $75, but I don't know whether that figure is still current.

I can't imagine it ever being done "routinely," given the huge number of coins that come through here daily.

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"Routinely" would only be for late 18th and early 19th century gold, and possibly only to 1804 for silver. Amortized test cost would be a lot less than $75. PCGS and NGC both make a substantial profit on this service under present very low utilization rates.

A couple of years ago I considered leasing equipment and offering the service at major coin shows. But the limited duration of shows plus G&A made it impractical.

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On 3/23/2022 at 5:59 PM, Oldhoopster said:

It would be a big contribution to the body of knowledge. 

Now that I do not have any prior commitments, I will devote my time by trying to determine why Yukon gold is different, and, of course, whether gold alleged to have been found in Ghana is markedly different, too.  One day, you'll say, "Q.A., I do believe I heard of him once. And  if, as you say, he made something of himself, I will take all the credit!"   😉 

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On 7/17/2022 at 12:51 PM, Quintus Arrius said:

Now that I do not have any prior commitments, I will devote my time by trying to determine why Yukon gold is different, and, of course, whether gold alleged to have been found in Ghana is markedly different, too.  One day, you'll say, "Q.A., I do believe I heard of him once. And  if, as you say, he made something of himself, I will take all the credit!"   😉 

Gold (and metal)  deposits are formed from melted rocks solidifying deep underground over long periods of time.  There's a lot of other stuff in the melt that will solidify at different times, sometimes staying separate, but most times forming oxides (think of granite).  Over time, extremely hot, highly pressurized water (because its deep underground) may circulate through the solidified rock and concentrate the metals. 

This happened over millions of years.  Since the composition of the original rock varied depending on the location, the trace minerals will vary as well in the metal.  That's why gold deposits are different.  

It's a little more complicated than that, but that's the general idea.  Hope this helps

Edit to add:

So if you know the trace element characteristics of the coin, you can match those concentrations with the metal in the ore body and get a general idea where the gold is from.  

Edited by Oldhoopster
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For anyone interested in pursuing a project like this, or if NGC decided to avail itself to providing XRF analysis "free" for coins that could benefit from this sort of learning experience, I would direct their attention first to purchasing a copy of the book Statistics For Experimenters (Box and Hunter).

This book is actually an enjoyable read, so much so that — as I found myself referring to the book many times from the laboratory library of the company where I worked — I bought my own copy.

My suspicions are that to undertake this project in a meaningful way, each coin that would undergo XRF would need to have several measurements taken and the data stored.  This would then open the door to revealing how many measurements per coin would be required, and also how many coins might be needed.  Both of these ideas — measurements per coin and number of coins — would be revised as more and more data would come in.

In the process of this project, just think how much you would learn:  experimental design, critical thinking, statistics, spreadsheet management, and the language of expressing results and conclusions.  This "general" skillset is in demand in all of the Science/Technology/Engineering/Mathematics (STEM) disciplines.  A young enough individual, motivated and with an outgoing personality, could write their "ticket" to work wherever they wanted with this sort of self-taught expertise.

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The same process can be used to aid determination of restrike vs original based on alloy differences caused by both immediate alloy mixing and time-based changes in refining capability. A simple example:

1836, 38, and 39 flying eagle dollars were evidently restruck on one or more occasions approximately 20 years after the original manufacture. Silver refining improved over this period, and the restrikes were almost certainly of higher quality alloy (fewer and/or different impurities). These data can be collected from multiple samples and used to separate originals from restrikes and empirical resolve current controversies about die orientation and other factors.

As USAuPzlBxBob implied, current technology makes this a simple, non-destructive data collection and statistical correlation project. If the two major TPGs decide to cooperate and coordinate data collection, results could be available within a year or two as the dollar coins cycle though sales and owners. The TPGs could also make a meaningful, positive contribution to numismatic knowledge by offering to reholder specimens gratis. 

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On 7/17/2022 at 1:34 PM, Oldhoopster said:

Gold (and metal)  deposits are formed from melted rocks solidifying deep underground over long periods of time.  There's a lot of other stuff in the melt that will solidify at different times, sometimes staying separate, but most times forming oxides (think of granite).  Over time, extremely hot, highly pressurized water (because its deep underground) may circulate through the solidified rock and concentrate the metals. 

This happened over millions of years.  Since the composition of the original rock varied depending on the location, the trace minerals will vary as well in the metal.  That's why gold deposits are different.  

It's a little more complicated than that, but that's the general idea.  Hope this helps

Edit to add:

So if you know the trace element characteristics of the coin, you can match those concentrations with the metal in the ore body and get a general idea where the gold is from.  

Ironically, I watched a very good History channel video that explained this almost exactly as you said. In California in particular, seismic activity pushed plates of the earth's crust into buckled ridges forming shelfs with long cracks running though these bucked plates, like this /\/\/\/\/\/\/\/\/\. The heat of the below mantle and the force of rock crushing rock created intense heat that pushed extremely hot liquid (liquid quartz essentially) that collected particles of gold that went into the cracks between the buckled plates. The liquid cooled, and so did the newly concentrated gold. What was left over is quartz gold veins. 

The difference in gold come from the different impurities contained within (platinum, silver, etc.) 

@Quintus Arrius, I could send you a link to the video if you wished. The visual would probably make more sense than my description.

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Good! By making careful measurements on 1848 CAL quarter eagles, we might be able to identify the district from which the gold originated. (Although the coins were made from refined gold, the Mint's work left many trace elements including iridium, osmium and platinum.)

Edited by RWB
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On 7/18/2022 at 3:47 PM, FlyingAl said:

Ironically, I watched a very good History channel video that explained this almost exactly as you said. In California in particular, seismic activity pushed plates of the earth's crust into buckled ridges forming shelfs with long cracks running though these bucked plates, like this /\/\/\/\/\/\/\/\/\. The heat of the below mantle and the force of rock crushing rock created intense heat that pushed extremely hot liquid (liquid quartz essentially) that collected particles of gold that went into the cracks between the buckled plates. The liquid cooled, and so did the newly concentrated gold. What was left over is quartz gold veins. 

The difference in gold come from the different impurities contained within (platinum, silver, etc.) 

@Quintus Arrius, I could send you a link to the video if you wished. The visual would probably make more sense than my description.

It helps to have an interest in geology.  I spent some time during my career working with ceramic raw material suppliers, picked up some basic knowledge, and tried to learn more whenever possible.

Nothing like riding around a talc mine at 7700 ft in Montana surrounded by huge Cat trucks and loaders.

 

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