Metal Porn Supplemental: The Baht Chain Mad Scientist Edition
Weiss
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So I mentioned two weeks back that I had a 5 troy ounce, 24k gold necklace hand made for me?
I happen to live in a town adjacent to one of the biggest engineering campuses in the world--and they have whole schools devoted to materials sciences and technology.
I arranged to visit one of their professors who specializes in micro- and nano-material technology and he introduced me to one of his advanced students who is the main lab technician. Together, we did a pretty thorough energy-dispersive x-ray analysis of the necklace to find out if it really is .9999 pure gold, and if not, what purity it is.
The x-ray analysis lab itself is pretty amazing. They're primarily producing and testing crystaline structures of new materials to be used in emerging technology.
This is a high resolution xray fractometer--one of three in the lab--that they use for analyzing crystaline structure. They run close to $100k each.
For the chain, they decided on the Shimadzu EDX-7000 Energy Dispersive X-ray Fluorescence Spectrometer. It's capable of measuring very tiny samples without being destructive and with a high degree of accuracy. This device runs $15,000 to $30,000 depending on the set up (computer, software, etc). This one was attached to a tank of uber pure helium, IIRC, to give it the most precise readings possible. Crazy cool stuff.
Here's the EDX with my necklace positioned over the 5mm lens of the device:
After running a diagnostic and calibration on the spectrometer, the first test began. This initial analysis took maybe 3 minutes start to finish. The device measured every element present above a certain threshold--designed to weed out environment. For example, we didn't want to see the oxygen, helium, or carbon present around the sample. Those are part of the natural environment and didn't have any bearing on the chain's purity.
Once the initial "broad scan" test concluded, the software displayed all of the elements present (again, excluding non-metallic environment). The test produced some interesting results. The xray spectrometer showed the necklace to be mostly pure gold. Also present in much smaller amounts were a few elements that weren't surprising: Silver, Iron, and Potassium. Those could be explained by the crucible in which the gold was melted, or even the sweat of my skin.
However, the device detected trace amounts of the rare earth elements Scandium, Samarium, and Neyodimum. We're talking .2% each, so far less than 1% of the total mass of the chain. But their presence kind of baffled the lab technician. Some of these are used in rare-earth magnets, which can be used in testing precious metals. We also hypothesized that their presence might be a ghost, kind of a false positive, if their chemical signature looked similar to the larger traces of silver, iron, or potassium.
So the next step was to run a "specific element" test with filters applied for these suspect materials. We omitted Potassium (K) from the list, figuring that it was most if not all surface contamination. This second test took a little longer to complete, and its accuracy is in part dependent on the length of time the test runs. The idea was that if these trace elements appeared even after filters for them were applied, we'd know with much greater certainty that these elements were present.
After that final analysis was concluded, the results were pretty impressive. Based on the best technology we could apply, this chain that was supposed to be .9999 pure is about as close to that as you can get with a real-world item produced in a jewelry store and worn on my neck for the last couple of weeks. Pretty cool, huh? 
--Severian the Lame
Comments
That's pretty cool!
I don't metal porn often, but my co-worker brought in his stuff he is getting rid of at some point. Thought I'd stack it up and take a pic.
way cool
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Very interesting, thank you for sharing !!!
Great report, Weiss. I learned something new today.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
@Weiss ....Very interesting report and glad to see the results were as expected. Cheers, RickO
@Weiss I was about to ask if you’d had a chance to do the testing.
Sincere thanks for the report.
Thanks, guys. Would I have posted this lengthy report if the chain had been significantly less than 99.9% pure?
When we finished, the technician invited me to come back if I ever had anything else I wanted to test. That's a gracious offer--they're very busy professionals. I imagine if I'd had to pay for an analysis like this it would have run several hundred dollars if not more.
But he seemed to have genuinely enjoyed using his knowledge and experience in a non-academic, real world application. I racked my brain to think of anything else I had that would be interesting to test, that my arsenal of equipment (Sigma tester, acid test kit, digital scale, digital calipers, rare earth magnets) was unable to test.
I mentioned I had the first coin ever made. The "trite" from the country of Lydia in what is now western Turkey. It's my icon on this page and has been for 10 years or more. It's made of electrum--the natural alloy of gold and silver found in streams around that region. It would be interesting to see what the ratio is, and if there are other elements present.
It's in an NGC holder now. But the technician thought there was a good chance the spectrometer would be able to see through it.
--Severian the Lame
Fascinating stuff. I'd be very interested to see what the test run had to say about that Lydian coin.
Here's a warning parable for coin collectors...
Forgot to mention I shared the analysis with the jeweler who made the chain. His reaction was predictable: Duh. I told you.
But I think he was glad for the scientific affirmation.
FWIW: My piece had been formed from APMEX .9999 gold grain or "shot", specifically used for jewelry. He showed me the receipt.
https://www.apmex.com/product/22778/1-oz-gold-grain-shot-9999-fine-order-by-the-ounce
--Severian the Lame
Awesome thread!
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That was one of the best reads I've had in a while. Extremely interesting. Thanks for sharing
@Weiss Do you know how deep the machine tests? I know that the smaller XRF machines only test a few microns deep.
@davidk , the technician said they have confidence in this device up to 10 microns. Apparently the disadvantage of any xray device is that the more energy you throw at an object doesn't go deeper, it just disperses more.
--Severian the Lame