Pyrites specimen?

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TTKooAu

TTKooAu

Grant Westbrook
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A buddy of mine has this specimen with pyrites visible, but given it's pedigree we suspect it may contain some colour.
Ramjet kindly gave me a link to a Specific Gravity calculating video, so we will get set up and work out the gold content.
The specimen has a fair amount of quartz in it but I'm not sure what the red material is, should I assume a specific gravity of 2.6 to 2.65 like you would for quartz?
1383794201_img_0017.jpg

1383794240_img_0018.jpg

1383794268_img_0021.jpg


Anyway, once I get it worked out I'll get back to this.

TT
 
G'day TT, sorry to say but you have buckleys of working out the gold content of that with a SG test. There are too many different minerals of unknown quantities in that specimen which will mess with your results.
The only real way of testing it is to crush it into a fine powder and pan it off. Often with pyrites like that the gold is locked in the sulphides and needs to be roasted to release it.
Good luck with it.

DD
 
What about sulphuric acid Diggerdude? Could he possibly put some acid on the pyrite, or can pyrite handle the acid? Is Pyrite mixed with gold a different substance?
 
Sulphuric acid might not be ideal, as Pyrite is iron sulphide, and decomposes into sulphuric acid when leached with water. Hydrogen sulphide gas will also be another undesirable byproduct from adding acid.

One of the main reasons why the old timers only took gold from oxidised material in the old mines, is that the sulphides had broken down and oxidised ovef time, leaving free gold in the ore. They could not extract gold from complex sulphides found in the fresh rock/veining at depth.

I'd just keep is as a nice specimen, but be aware that pyrite will eventually oxidise over time when exposed to the air. :)
 
Never tried sulphuric but doubt it would work. The idea of roasting it is to oxidize the sulphur out and therefore release the entrapped gold.

DD
 
I'm pretty sure to test with Stannous Chloride the gold must be in solution with either Aqua Regia or other solution.
 
So I just happened to be in the shed trying out my recently arrived Falcon MD20, when I passed it over the lump of red rock I have had for a while, believing it to be layered with pyrites. The MD20 seems to be telling me that there is some kind of metal within the structure.....hmmmmm.

https://youtu.be/L7LXpUOQ3dw

After filming the previous video, I turned up the sensitivity of the MD20 to just under its threshold and tried everything again.

https://youtu.be/kECEQvoVrf4

So I had to crunch the pyrites outcrop and see....(note the classic dohh moment.... :8 )

https://youtu.be/GCURv9fNT3g

Well the panned out results showed about 5 very tiny specs of metal that looked like gold, and I could only see them with a 30x voile, but they don't show once photographed with the usb microscope, the lights from the scope seem to blend them in with the colour of the accompanying pyrites and mica. This leads me to the conclusion that it isn't gold, from my experience gold always looks like gold, regardless of light condition.

As for the red rock, any of you had experience with a Falcon MD20?. Am I using it correctly?

Cheers TT
 

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