Contributed by Bob Evans, Curator of the Treasure of the SS Central America
Three of the seven gold assayer ingots selected for use in the Forty-Niner “Horseman” Commemorative Coin program provided valuable samples for cutting-edge research into the nature of the ingots themselves.
For our detailed chemical analysis of the gold, my colleagues and I used small samples, less than 2 grams, which were taken from Justh & Hunter ingots with serial numbers 4220, 4258, and 4282. Portions of the samples were submitted to a laboratory for modern bullion assays for gold and silver, allowing us to check the accuracy of the original assays, as stamped on the bars. Another small portion of each sample was submitted to another lab for inductively coupled plasma optical emission spectrometry (ICP). This method, with its complicated-sounding name, is useful for determining miniscule traces of other elements present in the sample, and for demonstrating the unique individual chemistry of the ingots. A small “chunk” of each remaining sample was examined using a scanning electron microscope and its electron dispersive spectroscopy function.
This testing is part of a comprehensive study of historical ingots that I am conducting with the cooperation of two other geologists: Fred Holabird, mining geologist and Americana dealer, and David Fitch, mining geologist. Both Holabird and Fitch have been involved with the production of ingots from mining operations, and Holabird has researched historical gold and silver ingots for many years as an expert in mining history.
Questions regarding the authenticity of certain ingots have cast shadows over this area of numismatics for the past few years. The uncertain provenance of the material stems from several sources: Sometimes, unknown material emerges as it is found with metal detectors or blind luck, buried in various places. Also, source information was potentially lost during that period from 1933 until 1973 when it was illegal for Americans to own gold bullion, and the holders of historical ingots either turned them in to the government or kept them a closely-guarded secret. In some cases, those owners passed away without ever conveying the history of the materials to their heirs. In addition, and in recent years, counterfeit ingots may also have been produced. Obviously, these false products share a lack of provenance information with possibly genuine bars.
The ingots recovered from the SS Central America provide an unquestionably authentic standard against which the characteristics of other ingots can be measured and compared. The ingots from the “Horseman” Forty-Niner Commemorative Coin program are particularly valuable because they have provided tiny samples for destructive testing (the few tenths of a gram used from each of these samples is not recoverable). The techniques of these modern scientific tests produce results more accurate than other, non-destructive methods, and the results of the methods can then be compared.
During my ingot studies I have travelled around the country examining the microscopic details and overall character of ingots held in major collections, including those housed in the National Numismatic Collection at the Smithsonian Institution, and the Bank of California Collection in San Francisco. The results of these examinations are being compiled and the data are being compared to the information derived from the SS Central America ingot samples provided by Monaco Financial.
I am very excited about this research and the opportunity the ingots from the “Ship of Gold” afford to cast the light of truth on the sometimes difficult subject of historical ingot authenticity. Such ingots speak volumes about the people and practices that made them. But only when authenticity can be established can stories be trusted. I hope that these studies contribute to a clearer understanding of genuine historical treasures.