DesertNuggets Posted January 26, 2016 Report Share Posted January 26, 2016 I found this metal detecting the other day. I didn't think much of it until I got home.. It was like 80% black. Some sort of tarnish. This is what it looks like after a short soak in acid. Its a brassy color in the sunlight. Extremely heavy for its size. Looks well traveled and that makes sense considering where I found it.It passes a 14k gold test but nothing higher. Fails platinum and silver tests.Dry weight: 1.16gSpecific gravity: 19.33 Quote Link to comment Share on other sites More sharing options...
Gold Seeker Posted January 26, 2016 Report Share Posted January 26, 2016 Well the specific gravity if your calculations are correct is dead on for it being pure gold, or is has other metals in it that add up to the same specific gravity of gold. I would suggest using a XRF spectrometer to find it's hidden secrets. Quote Link to comment Share on other sites More sharing options...
Tortuga Posted January 26, 2016 Report Share Posted January 26, 2016 Some kinda not-so-pure gold nugget? Quote Link to comment Share on other sites More sharing options...
Admin nuggethunting Posted January 26, 2016 Admin Report Share Posted January 26, 2016 Hey DesertNuggets, No question it's a gold nugget, but probably more of an Electrum nugget. Many gold nuggets contain a much higher silver percentage, some as high as 20% or more making them an Electrum nugget (80% gold, 20% silver). Hope this helps a bit, Quote Link to comment Share on other sites More sharing options...
Gold Seeker Posted January 27, 2016 Report Share Posted January 27, 2016 Hey DesertNuggets, No question it's a gold nugget, but probably more of an Electrum nugget. Many gold nuggets contain a much higher silver percentage, some as high as 20% or more making them an Electrum nugget (80% gold, 20% silver). Hope this helps a bit,Rob, I was thinking Electrum as well but he said it tested negative for silver. Quote Link to comment Share on other sites More sharing options...
DesertNuggets Posted January 27, 2016 Author Report Share Posted January 27, 2016 Thanks guys and Rob. I was thinking maybe electrum with some sort of pgm. Palladium maybe.Maybe it failed the silver test because it's alloyed? Or maybe my silver test solution is bad. It's a couple years old. Or just might not have silver in it.I'm going to try to find a place to XRF it for me. Quote Link to comment Share on other sites More sharing options...
boulder dash Posted January 28, 2016 Report Share Posted January 28, 2016 I think it's gold, try cutting a little window in it. Quote Link to comment Share on other sites More sharing options...
adam Posted January 28, 2016 Report Share Posted January 28, 2016 Platinum does not tarnish- However, silver does tarnish the same way it looked before you cleaned it. I would lean on electrum, or mercury coated gold Quote Link to comment Share on other sites More sharing options...
Tortuga Posted January 28, 2016 Report Share Posted January 28, 2016 I think it's gold, try cutting a little window in it.Good idea but with something so small I'd just leave it as is. If it was a couple ounces or something I'd definitely be more inclined to know. Quote Link to comment Share on other sites More sharing options...
boulder dash Posted January 29, 2016 Report Share Posted January 29, 2016 Adam has a good point. Could it be covered in nasty looking mercury. Try heating it with a torch in the outdoors. Quote Link to comment Share on other sites More sharing options...
jasong Posted January 29, 2016 Report Share Posted January 29, 2016 Give it a streak test on the back of your toilet lid or some other unglazed ceramic, gold streaks gold, brass is more brassy-brownish. Or if you have some nitric acid, brass starts reacting right away, gold doesn't do anything. XRF is definitive though.19.33g/cm3 is too dense to be 14k gold so I would try the specific gravity test again.I've found electrum nuggets down to 59% gold/41% silver, none of mine have been tarnished out of the ground though but who knows maybe different soil types react different, so with all that oxidization on it I'd have to guess brass brazing slag but these things are impossible to tell from pics.Make sure to reply back after you figure it out one way or another, a mystery needs a solution! Quote Link to comment Share on other sites More sharing options...
Afriscot Posted January 29, 2016 Report Share Posted January 29, 2016 Rob, any chance this nugget is manganese coated nugget like the ones that we find? Quote Link to comment Share on other sites More sharing options...
DesertNuggets Posted January 29, 2016 Author Report Share Posted January 29, 2016 Thanks everyone. I torched it. Same color. Still brassy. I soaked it in pure 10k test solution and it didn't even react. Maybe I'll try higher. The little window I created when I did my gold/silver/platinum test is pure brassy. None of that black stuff is on the inside.Still no luck finding an XRF scanner. Gold buyers and jewelry stores are who I should be calling right? Quote Link to comment Share on other sites More sharing options...
DesertNuggets Posted January 30, 2016 Author Report Share Posted January 30, 2016 Well I torched her again but this time for longer. She is looking much more like gold now. I'd say the brassyness is gone and it's just a light yellow now. Looks just like lower purity gold. I give up on specific gravity tests. With a sowing string I get 19.33. With a paper clip I get 10.54 or 11.6 depending on where the nugget is in the water column. Quote Link to comment Share on other sites More sharing options...
jasong Posted January 30, 2016 Report Share Posted January 30, 2016 Merc reacts to nitric acid (10k testing solution) so it can't be mercury if you didn't see a reaction. The torch must be oxidizing something if the color is changing.I'd give it a streak test. Difference between low purity gold and brass is pretty easy to spot on a streak. Quote Link to comment Share on other sites More sharing options...
Dakota Slim Posted January 30, 2016 Report Share Posted January 30, 2016 Pegleg found a bunch of black nuggets. Quote Link to comment Share on other sites More sharing options...
adam Posted February 5, 2016 Report Share Posted February 5, 2016 A friend found a black nugget one time , it wound up being brass. It had a black tarnish or something on it. Quote Link to comment Share on other sites More sharing options...
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