So I had my Athenian owl and Faustina aureus X-rayed today. I know there are many discussions about the possible purities on these… well, on these, we have definitive answers: The results:
I am new to ancients, but just going on my observations, my guess is that both, their intentions were pure gold and silver, given that all of the other impurities are spread out pretty evenly among many other elements…. I am interested to see what the others think. Please discuss.
XRF only penetrates to a depth of 100 microns or so (lots of things that could cause it to be more or less, but I find 100um to be a good working estimate). So you're only measuring the surface, which could be different from the bulk if any processing or environmental enrichment occurred. I would say that the Ag and Au of the surfaces should be close to the 96% and 93% you posted Also, I wouldn't put a great deal of faith in the trace elemental analysis unless the unit was calibrated for those elements. Since so many energy peaks overlap, the algorithm needs to be pretty good to get that data.
Perhaps the other normal heavy elements are father down the list and not visible on the screen , such as ones like lead are usually associated in small % with gold and silver. The refining of flakes can produce a different % of the associated metals than vein or nugget ore. IMO, Jim
IMHO, unless the coins are out of the case, PREPARED to remove contamination, and then put on a REAL piece of equipment in a major lab that does these kind of examinations on an hourly basis; the results may not be precise enough to put into a research paper. Anyway, I guess your coins are genuine and mostly made of silver and gold. Thanks for posting. I wish every coin minted before 1900 could be "fingerprinted" in this way. I have read that researches have been able to determine the mine where the silver used to make the coin came from.
Assuming the coin was made primarily from metal obtained by smelter ore. Each ore deposit will have different types and amounts of trace elements, so with accurate analytical equipment, developing a "mine fingerprint" is possible The problem with coins is that mints had a tendency to remelt older, worn out coins, higher purity coins (if they are debasing the new coins), and coins from other regions. Those things can throw the analysis off, making the determination of the ore challenging.
Oh geeze I want one of those analyzers. When I first became aware of them, they cost about as much as a new car. With things as they are, they're now closer to half or a third of a new car. But I want one a lot more than I want a new car.
Was looking at SEMs for work about 10 years ago. A bench top model was only $75k. Now that would be cool to have in the basement
your sample size is too small...you can't gain any empirical data without many more research samples.
They dropped and then went back up. Maybe the same problem of many electronic devices. A nanoimage unit is at a "low" level with approx. 60,000 for the base unit. Accessories extra But the resolution is much better than the one I trained on in 2015-17 (I forget exact ). Jim
I think your machine needs calibrating. I’ve xrf tested 1000’s of coins including several hundred Athenian tets and aurei. Never, and I mean never does ruthenium and indium appear, and only in minuscule amounts do cobalt, rhodium and palladium show up. The top are always gold and silver depending on the coin, then copper, lead and gold or silver (the opposite of the coin). Next on the list would be zinc, nickle, iron, arsenic, tin. Only then would you possibly hit rhodium, cobalt and palladium. It’s even more unusual that the same, very rare in not non-existent metals in these coins, shows up on both your tests. Barry Murphy
When I wanted to check on the metal content of an ancient coin, I went to a mining engineer. His business is to test the purity of bullion and ore samples. He had the equipment and of course knew how to use and calibrate it. I had various parts of my coin examined by electron microscope and xrf. Since he was an individual operator, and I a collector, his rate was reasonable. My recommendation is to find a similar operation in your area. Given the value of your coins, that you want only two pieces tested, and since you are an individual, I’m sure the experience will be both affordable and educational.
Well they were scanned through the slab, maybe that's why? No idea. It's a friend that has the scanner, it was done just for the heck of it. I'm not really worried about pursuing it further, I just thought it made for an interesting thread and it gives me a ballpark on their purity... Thanks for the replies everybody!
