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Author Topic: How to tell if gold in rock is real?  (Read 19986 times)

2gloves

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How to tell if gold in rock is real?
« on: 07/01/2013 23:55:54 »
Sorry I'm new. Hope to find help here.
Take a look at the picture please.
What steps can I do to test, remove the gold, etc?

CliffordK

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Re: How to tell if gold in rock is real?
« Reply #1 on: 08/01/2013 01:36:34 »
Isn't "Real" somewhat relative?   

Your Iron Pyrite looks quite real to me.

The resolution of your photo is a little course, but pyrite is supposed to have a cubic structure which I believe your crystals have.

Pyrite is also a semiconductor.  I'm not quite sure the resistance, but if you had gold, there would be viurtually NO electrical resistance from one side of a flake of gold to the other.  Try an ohmmeter, and you should find at least some resistance.

RD

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Re: How to tell if gold in rock is real?
« Reply #2 on: 08/01/2013 03:19:53 »
 Iron Pyrite is magnetic, Gold isn't.

Quote

Simple field tests can reveal whether you have encountered real gold or Fool's Gold. Fool's Gold will scratch glass whereas real gold cannot. Additionally, being composed with Iron as a basic ingredient, Fool's Gold will be attracted by magnets while gold and other precious metals are not affected by magnetic fields.
http://www.gold-traders.co.uk/gold-information/what-is-fools-gold-made-of.asp

Boogie

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Re: How to tell if gold in rock is real?
« Reply #3 on: 08/01/2013 03:53:45 »
I thought Iron Pyrite needed to be fused before becoming magnetic?

Anyway, if you think you have visible gold, take an unglazed tile of ceramic (underside of your toilet lid will work) and scratch the mineral against it. If it's gold, you will get a gold streak. If it's fools gold (pyrite), you will get a black streak. Fool proof!


Don_1

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Re: How to tell if gold in rock is real?
« Reply #4 on: 08/01/2013 12:28:17 »
....... And if you get a brown streak, you've pooed yourself.

Bill S

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Re: How to tell if gold in rock is real?
« Reply #5 on: 08/01/2013 19:24:00 »
Quote from: Boogie
If it's fools gold (pyrite), you will get a black streak.

Or just a scratch on the inside of your toilet lid.  Streak plates are of very limited value with the harder minerals.

CliffordK

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Re: How to tell if gold in rock is real?
« Reply #6 on: 08/01/2013 19:29:39 »
One should note that gold may be found in some of the same places that iron pyrite is found.  So, while the gold color in your stone may not be elemental gold, it is quite possible that there would be a s all amount of gold contained in the stone.

Bored chemist

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Re: How to tell if gold in rock is real?
« Reply #7 on: 08/01/2013 20:51:50 »
Iron Pyrite is magnetic.


No it's not.

Bill S

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Re: How to tell if gold in rock is real?
« Reply #8 on: 09/01/2013 00:41:58 »
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No it's not.

B C is right, of course, but heated in a closed test tube, or on charcoal with sodium carbonate, it leaves a magnetic residue.

Bored chemist

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Re: How to tell if gold in rock is real?
« Reply #9 on: 09/01/2013 09:27:14 »
Heating things in closed containers like test tubes isn't a good idea.

Heating pyrites in the presence of air will oxidise it to a mixture of iron oxides (which will be magnetic) and sulphur dioxide which stinks and is somewhat toxic so I'd not try it indoors.

Bill S

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Re: How to tell if gold in rock is real?
« Reply #10 on: 09/01/2013 20:29:39 »
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Heating things in closed containers like test tubes isn't a good idea.

Have not tried it myself, but when I first met the idea I had grave doubts about its safety.  :)

OokieWonderslug

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Re: How to tell if gold in rock is real?
« Reply #11 on: 10/01/2013 02:28:34 »
Heating things in closed containers like test tubes isn't a good idea.


Yeah I did that once and it exploded. Left a permanent stain on my ceiling.

Boogie

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Re: How to tell if gold in rock is real?
« Reply #12 on: 11/01/2013 21:50:10 »
Quote from: Boogie
If it's fools gold (pyrite), you will get a black streak.

Or just a scratch on the inside of your toilet lid.  Streak plates are of very limited value with the harder minerals.

I guess you would know then, that you don't have gold right? The OP was asking for a test for gold.

Bass

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Re: How to tell if gold in rock is real?
« Reply #13 on: 12/01/2013 02:31:58 »
crush the rock really fine (say -80 mesh) and pan.  If there is any coarse gold, it will remain in the bottom of the pan.
Even easier, send the rock to a laboratory, and have them run a gold assay on it.  Fire assays are more accurate, but also more expensive.

2gloves

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Re: How to tell if gold in rock is real?
« Reply #14 on: 14/01/2013 06:44:10 »
Iron Pyrite is magnetic, Gold isn't.

Quote

Simple field tests can reveal whether you have encountered real gold or Fool's Gold. Fool's Gold will scratch glass whereas real gold cannot. Additionally, being composed with Iron as a basic ingredient, Fool's Gold will be attracted by magnets while gold and other precious metals are not affected by magnetic fields.
http://www.gold-traders.co.uk/gold-information/what-is-fools-gold-made-of.asp
Ok, I took a file and filed some of the "gold" & rock and placed the filed flakes onto a magnet. Not magnetic. I then placed the rock/gold grinds that I filed and put into a gold pan. They stayed at the bottom.
Next step to try an ohm meter. Also I thougt I read somewhere about using acid to test gold?
Thank you all for your thoughts and input:)

Bill S

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Re: How to tell if gold in rock is real?
« Reply #15 on: 18/01/2013 20:48:45 »
2gloves, have you tried cutting your specimen with a knife?

Gold can be cut, pyrite will blunt your knife before you will make an impression on it, chalcopyrite will crumble.

Another good test is to heat a small amount to melting point, preferably on a charcoal block.  All compounds of gold will give you a malleable bead of gold.

Spacetectonics

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Re: How to tell if gold in rock is real?
« Reply #16 on: 24/02/2013 18:18:39 »
Easy one!
Gold No reaction to acid!
Fool gold solves in acid!
Aqua regia ..I think could!!

http://en.wikipedia.org/wiki/Acid_test_%28gold%29

:)
« Last Edit: 24/02/2013 18:33:26 by Spacetectonics »

CliffordK

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Re: How to tell if gold in rock is real?
« Reply #17 on: 25/02/2013 05:36:44 »
I found this piece of pyrite for sale recently.



At least I think it is pyrite.

Anyway, I confirmed that a magnet does not stick to it at all.

I'll check the electrical conductivity as soon as I can find a 9V battery.

CliffordK

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Re: How to tell if gold in rock is real?
« Reply #18 on: 09/03/2013 09:28:13 »
I got my electrical multitester working again.  & a little bigger piece of pyrite. 

My NdFeB magnets still don't stick to the pyrite at all.

Depending on my crystal size, and where I was measuring it, I was getting a resistance of 1000 to 3000 ohms across larger crystals.  A gold nugget would be much closer to ZERO.  Gold embedded in another matrix might be more variable.

Bored chemist

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Re: How to tell if gold in rock is real?
« Reply #19 on: 09/03/2013 19:59:04 »

My NdFeB magnets still don't stick to the pyrite at all.


That may well reflect the fact that pyrite isn't magnetic.

 

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