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Sounds like it's got some mercury sticking to it. You can drive off the mercury with heat, just make sure that you do it outdoors and stay upwind. (Better yet, get or make a mercury retort to recapture the mercury.) An overnight soak in vinegar might also do the trick.

Rick

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Yep! Mercury would NOT go black!

It's Manganese oxide or some other ferrite oxide.

A bath in muriatic acid should do the trick.

It will not mess with the gold.

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Muriatic acid is what they use to clean brick, concrete, stone, etc., you should be able to find it at home improvement/ hardware stores, you can also get it at any place that sells swimming pool chemicals.

Follow all the precautions on the label, i.e. rubber gloves, safety glasses, avoid contact with skin and don't breathe the fumes, etc.

http://www.homedepot.com/webapp/wcs/stores/servlet/Search?keyword=muriatic+acid&selectedCatgry=SEARCH+ALL&langId=-1&storeId=10051&catalogId=10053&Ntpc=1&Ntpr=1

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Any hardware store..be sure to have some baking soda and water handy to dump the piece in after the acid bath to neutralize any acid residue.Scrub with an old toothbrush dipping it in the baking soda paste.Watch your eyes and if on your skin will burn it and turn yellow.If the muriatic dosen't work,,use nitric if you can find it.Much more dangerous however.

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If the muriatic dosen't work,, use nitric if you can find it. Much more dangerous however.

Nitric acid should only be used when you know the exact purity of your gold. Anything below 14k will be dissolved.

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Nitric acid should only be used when you know the exact purity of your gold. Anything below 14k will be dissolved. If that happens then you'll have to precipitate out of solution.

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K Mart probably has Meriatic!

Lime Away has some in it and may do the job.

Yep, It will HURT you if you don't use Common Sense. It makes fingers go away in about 30 seconds flat.

Keep a bucket of water mixed with baking soda at hand.

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Yep, muriatic acid is safe as long as you hold your breath while pouring it in the jar and putting a lid on it and while pouring it out and then diluting the remaining residue with water. We used to clean the iron oxide off of corundum with it.

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Muriatic is crazy stuff. I had a jar with about 2oz in on the work bench. Maison type jar, lid secure and tight.

Every thing metal within 2ft of it Rusted in two days.

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Simple thing to try.... peroxide. Had black coating on my bigger nuggets as well. Hydrogen peroxide dissolved it overnight. IF of course its the same staining I experienced. Nuggets were black as a boot. Almost threw them out.. if it was'nt for another forum member...i probably would have :yikes:

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That is pretty odd, and I wonder how many times I tossed them thinking it was garbage. I think I have some picker sized gold at home, which I thought was iron mixed with gold. I never thought it might be a coating. I often find gold mixed in with some type of white soft rock (not quartz) It reminds me of chalk. I figure it is just low grade ore.

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  • 2 years later...

Can you guys please post pics of these black gold nuggets? Or send me an email with the photos? I tossed out a nuggety looking fist size, super heavy, black rock some years back and have been kicking myself ever since after reading about black gold nuggets since then. The area I was in had red/orange river bedrock, tons of hotrocks, and mudholes to boot, and evidence of mining all over the place and craters in the limestone ridges. My MXT meter in Prospect mode blanked out over this rock at a foot deep, altho it screamed like a silver dollar. Ps, how did your detectors react to these black gold nuggets?

Thanks.

-Tom

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Can you guys please post pics of these black gold nuggets? Or send me an email with the photos? I tossed out a nuggety looking fist size, super heavy, black rock some years back and have been kicking myself ever since after reading about black gold nuggets since then. The area I was in had red/orange river bedrock, tons of hotrocks, and mudholes to boot, and evidence of mining all over the place and craters in the limestone ridges. My MXT meter in Prospect mode blanked out over this rock at a foot deep, altho it screamed like a silver dollar. Ps, how did your detectors react to these black gold nuggets?

Thanks.

-Tom

Tom, all of the black nuggets I have heard of could be scraped to reveal the color of the gold, most of them are only covered with a thin manganese coating.

Here's one such manganese coated gold nugget that has been posted on the internet, it's not completely covered with the manganese coating but you can get the idea of what it would look like if it was.

DSC_0008copynx.jpg

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Yup, that's what it looks like. I get lots of them.

Just stick in your lower lip and when you get back to the truck, it'll be shiny gold!!

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Was replying to azblackbird,bro.

NOpe- to the forum for all to reply to.

I wouldn't mess with A/regia,either, when "RUST AWAY", LIme AWay, Vinegar,Oxalic or pool acid( HCL) will do the job.

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