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Copper Nodule From Nevada?


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Found a copper ore nodule scanning some mine tailings in n Nevada, 94 on the Deus and very heavy. XRF readings at the local pawn shop were; Fe 1.53%, Zn 27.37%, Sn .632%, Cu 67.68%, Pb 2.37%. Sure wish there was a little Au in there, next time I wish. Or, could this just be a melted fitting buried in the tailing pile way in the desert high on the side of a hill?

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Ya, you sure do find all kinds of strange melted, rusted globs out there. Just one more thing to confuse us new guys...at least I never thought it was gold and the hunt goes on. Keep telling myself the only way for sure to not find gold or anything else cool is not to try, still it's a head game.

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Looks like you cleaned this up between photos.  What were the steps you performed?

Just brainstorming here, but I sometimes wonder how accurate these XRF measurements are.  One interesting thing (IMO) is the 1.5% iron content.  Looking at Wikipedia:

https://en.wikipedia.org/wiki/Brass

I see that there is something called "manganese brass" which is very close in composition to what you have, except with manganese instead of iron.  Manganese is the next door neighbor of iron in the periodic table, and that means its X-ray line energies are close to iron's.  Could the XRF identification be incorrect and this is manganese brass?

 

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Hi GB, The first treatment was a quick scrape with a knife blade while visiting with Peg Leg John at his trailer on my way back from the hunting grounds, I always stop in to say hi and see how John's doing. Also, his money has been tight for him lately and he had some trouble with thieves and such in the area, so I buy some crystals from time to time or try and make the day better in other ways if I can (gas, smokes..), the piece was pretty green from the oxidation and we thought galena with some copper, nothing that special. I was looking for information on the piles of dirt it came from so I thought 5 bucks for an XRF was worth the time. The middle pic is what it looked like at the time of the test. After testing for fun I tossed it in a big rock tumbler filled with park clad and laundry soap for a couple of hours and then gave it a buff with a buffing wheel and compound. Still worth the 5 bucks as everything tells me that chunk of melted brass has some age and those piles of red dirt and crystals have been there fore a while. 

The big crystal and some of the small ones as well as most of that trash came from the piles without going beyond the surface more than a few inches. The smoky quartz was a gift from john to my wife, he knows she likes rocks and sent her this on this trip. If you find yourself in the area stop in and pay him a visit, he appreciates the company, is very helpful and is full of great stories.

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  • 2 weeks later...

The percentages of the elements in your find from XRF match well with commercial brass known as Alpha brass. From Wikipedia: "Alpha brasses are malleable, can be worked cold, and are used in pressing, forging, or similar applications. They contain only one phase, with face-centered cubic crystal structure. With their high proportion of copper, these brasses have a more golden hue than others". The Romans used a gold colored brass alloy called orichalcum similar to your find to make coins. This is a Vespasian dupondius from 77-78 AD.

 

 

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