Unique, "EB on Breast"1787 Brasher Doubloon from
The Gold Rush Collection
The Coloration of Dahlonega Gold Coins
By Carl N. LesterPreface
It should be understood that the color of the Dahlonega gold coins was more a function of the minting methodology employed at the facility, than of the raw material from which they were produced. In fact, the Dahlonega Mint produced gold coins from a variety of gold sources: naturally-occurring gold (from Georgia, as well as other states), foreign gold coins, gold bullion, scrap gold, etc. The Dahlonega Mint even produced coins from gold that was brought in from great distances. For example, the Dahlonega Mint actually coined a great deal of California gold from 1851-1854, which was brought back by local miners returning from the California gold fields. Thus, there is no foolproof way to know whether or not a particular Dahlonega gold coin was produced from locally mined metal.In a nutshell, there is historical evidence, as well as modern scientific evidence, that the gold coins produced at Dahlonega had a "high" silver concentration (when compared with gold coins produced at the parent mint in Philadelphia). Although some other regions (such as California) generally had lower purity gold (with a much higher silver concentration than Georgia gold), the lower purity gold had to be refined prior to minting, thus removing most (or perhaps virtually all) of the silver. The resulting gold would then be alloyed with copper and perhaps a small amount of silver. Thus, the resulting gold coins had less silver than their Dahlonega cousins.
By the way, the "green gold" characterization of Dahlonega gold is a visual interpretation of color differences among coins and is therefore very subjective. It has been my experience that the green gold designation for Dahlonega coinage is fairly common in numismatic references and periodicals. However, I know one well-known numismatic author who characterized the color of Dahlonega gold coins as a "pale yellow." The point is: the Dahlonega coins generally have a different coloration, but that difference has been described in various ways by various experts. Another factor in discussing the coloration of gold coins is whether or not a specific coin is in the "original state," which usually means that it has an "aged patina," much as would a carefully preserved antique, or whether it has been cleaned/chemically treated.
Discussion
It is common knowledge in the numismatic world that, generally speaking, the coins from the two southern gold mints (Dahlonega and Charlotte) tend to have a lighter coloration than their Philadelphia Mint counterparts. I have studied Dahlonega gold coinage for several decades and am quite familiar with this characteristic. For the purposes of this discussion, I am referring to the coloration that the coins had when minted, and not to any “aged patina” (often called “toning”) that the coins acquired in subsequent years. Admittedly, since all of the coins from Dahlonega are now at least 141 years old, this is a “fine line” with something as subjective as one’s perception of a coin’s coloration, but a distinction that is necessary if we are to be able to make sense of this.By law, gold coinage during the operation of the Dahlonega Mint (1838-1861) was 0.900 fine, meaning 900 parts per thousand (by weight) pure gold. The remaining 100 parts constituted the alloy (pure gold being too soft and malleable to produce coins that would stand up to the rigors of circulation). By law for that time period, the alloy for gold coins was copper and silver, provided that the silver did not exceed one-half the alloy. Thus, the silver content could be up to 50 parts per thousand. It was therefore lawfully possible to have coins with varying concentrations of silver, about which we can today make observations relative to the coloration differences.
Generally speaking, a gold coin with 100 parts per thousand copper alloy is distinctly orange in color. Gold coins with silver and copper tend to be less orange, and if the silver content is high enough, the coins do not look orange at all, possessing a light “green gold” color. As a consequence of this imprecise specification for the alloy, the mints at Dahlonega and Charlotte had the flexibility to have a higher silver content than the parent institution, the Philadelphia Mint. Although it would be an interesting case study, I have not “analyzed” the coloration of the gold coins from the other branch mints (i.e., New Orleans, San Francisco, Carson City, and Denver).
Clair M. Birdsall authored an excellent book in 1984, entitled The United States Branch Mint at Dahlonega, Georgia: Its History and Coinage . As part of his groundbreaking research, Mr. Birdsall had a number of Dahlonega gold coins non-destructively analyzed (by X-ray fluorescence) for their silver content. The facilities which performed the analyses were the Chemistry Laboratory of Clemson University and the Central Scientific Laboratory of Union Carbide Corporation, Tarrytown, NY. Two standards were used for calibration of the silver content in these analyses: One was an alloy of known weights of gold and silver at the Union Carbide Corporation Tarrytown Technical Center. The second was an 1855 Philadelphia Mint gold dollar, which had been determined to contain 1.13% silver by a process known as ICP Emission Spectroscopy, also done at Union Carbide, Tarrytown. The silver content of the analyzed coins follows:
1838-D half eagle: 4.8 % (48 parts per thousand)
1845-D quarter eagle: 5.0 % (50 ppt)
1846-D quarter eagle: 4.3 % (43 ppt)
1847-D quarter eagle: 4.3 % (43 ppt)
1847-D half eagle: 4.0 % (40 ppt)
1850-D gold dollar: 3.7 % (37 ppt)
1853-D gold dollar: 3.9 % (39 ppt)
1853-D half eagle: 3.6 % (36 ppt)
1854-D half eagle: 1.3 % (13 ppt)
1854-D gold dollar: 1.4 % (14 ppt)
1854-D half eagle: 1.3 % (13 ppt)
1855-P gold dollar: 1.13 % (11.3 ppt)
I added the Philadelphia Mint gold dollar at the end for comparison purposes.
One notices that the Dahlonega coinage produced from 1838-1853 has a silver content of 36-50 parts per thousand, which is approximately 3.2-4.4 times higher than that of the lone 1855 gold dollar from the Philadelphia Mint.
One also notices the drop in silver content for the Dahlonega coinage produced in 1854. Mr. Birdsall noted in his book that apparently the Director of the Mint at Philadelphia, James Ross Snowden, had written to Dahlonega Mint Superintendent Julius Patton (in September 1853), where he pointed out that the coins produced at the Dahlonega Mint were a different color than those made at Philadelphia. Mr. Birdsall did not have access to Mr. Snowden's letter, but its content can be inferred by the reply letter sent by Supt. Patton on October 8, 1853. Patton states that he had maintained a silver content of 73 (parts per thousand), "but would now change to comply with your late instruction." Although the X-ray fluorescence analyses above do not confirm the 73 parts per thousand of silver claimed by Supt. Patton, they do indicate a significant drop in the silver content in 1854, in apparent compliance with Snowden's directive. Oddly, Supt. Patton’s claim of 73 parts per thousand of silver is actually above the legal limit of 50 parts per thousand. According to Mr. Birdsall, Mint Director Snowden claimed that the silver content of the Philadelphia coins was 8 parts per thousand, even lower than the 11.3 parts per thousand for the 1855 Philadelphia Mint gold dollar that was analyzed by Union Carbide. It should be noted that there may be 1853-dated Dahlonega half eagles (and possibly quarter eagles) that were minted in late 1853, after the Dahlonega Mint was directed to reduce the silver content, that have a silver content more in line with the 1854 Dahlonega coins that were analyzed.
Because of their low silver content, one might expect the Dahlonega gold coins of 1854 to be an exception to the "green gold" coloration of many of the Dahlonega coins. As an interesting “data point,” I recently purchased an 1854-D half eagle that is not “green gold.” In fact, it probably has the most orange coloration of any Dahlonega gold piece that I own. This observation is consistent with the low silver content of the 1854-D coins that were analyzed above. It’s unfortunate that Mr. Birdsall did not analyze more Dahlonega gold coins, including some minted after 1854, to see if the reduction in silver content was continued until the facility closed in 1861.
I have a theory as to why most Dahlonega (and Charlotte) gold coins were higher in silver content than their Philadelphia Mint counterparts. I also have a suspicion that the comparison would apply equally well to San Francisco Mint gold coins, which contained primarily California-mined gold. It is well-established that the gold mined in the southern Appalachian region was higher in gold content than the gold mined in California. The Georgia Gold Rush , by David Williams, states (on page 79) that “Georgia gold averages about 95 percent pure and is rarely less than 90 percent as compared with the 88 percent average of gold found in California and Alaska.” If one assumes that the average for the Appalachian gold was at least 0.950 fine, with the balance being silver, then it is obvious that the gold could be prepared for coinage simply by the addition of the proper weight of copper alloy (in order to reduce the fineness to the legal standard of 0.900 and still being assured of having no more than 50 parts per thousand of silver). On the other hand, if one assumes that the California gold averaged less than 0.950 fineness (and assuming that the 50 parts per thousand limit for silver was enforced), the only way it could be rendered acceptable for coinage is through a refinement process known as "parting," or separating the gold from the silver "impurity."
Thus, at least for the deposits of Appalachian gold, I believe that the Dahlonega Mint routinely left in the naturally occurring silver (the easier course of action if the fineness of the deposit was at least 0.950). The Philadelphia Mint apparently parted most of its gold, probably because of legal necessity, due to the high silver content. The evidence suggests that at the Dahlonega Mint some silver was added back in after parting, a process which it had to employ on occasion (especially during the early 1850s when it was receiving many silver-laden California deposits). However, the amount added appears to have varied from mint to mint. For example, Mint Director Snowden identified the silver “target” (in 1853) at Philadelphia as 8 parts per thousand. Dahlonega, on the other hand, when adding silver following the parting of a deposit with a high silver content (e.g., deposits from California), would typically have a silver “target” of between 25 and 50 parts per thousand. The silver content of the two analyzed 1853-dated Dahlonega coins (which probably contained California gold and thus had to be parted) fell within this range. According to data in the Birdsall book, approximately 79.4 % of all bullion deposits at Dahlonega in 1853 came from California. The high silver target at Dahlonega was revised after Mint Director Snowden’s directive in late 1853, resulting in coins with less silver content, at least for the 1854-dated coins which were analyzed.
In summary, we have contemporary evidence in the historical record that prior to 1854 the Dahlonega Mint produced coins with considerably more silver content than those of the Philadelphia Mint. The historical record also shows that the Mint Director at Philadelphia complained to the Superintendent of the Dahlonega Mint about the coloration difference in the coins produced at Dahlonega. He therefore directed Superintendent Patton to reduce the silver content. We also have modern scientific evidence (silver content of surviving specimens of Dahlonega coins) that confirms the high silver content of Dahlonega coins produced prior to 1854, as well as much lower silver content for Dahlonega coins produced in 1854, after the Snowden directive was implemented. Collectors today note the distinctive coloration of many Dahlonega gold coins, being described variously as a “pale yellow” or light “green gold.”