The chemistry of supergene enrichment???

[Ragnor]

Well, I been looking into it. My brother and I have been trying to get as good of understanding as we can of the processes involved. It seams there are two kinds of supergene. One where the calcite vein material gets disolved by sulphuric acid causing the gold to mobilize down the vein forming a pocket and another where the gold and sulphides are actually disolved into solution and travel until they come in contact with a basic component causing the gold to precipitate.

I think my undersanding is pretty clear on the first case. However I am wondering if anyone can better explain the chemistry of the second type described here.

What actually disolves and mobilizes the gold bearing material and sulphides. Sure sulphuric can disolve some materials but wouldnt it need a nitric component to disolve the gold? and what exactly would precipitate it? The best we have figured out is gypsum or somthing of that nature?

Would testing for basic ground conditions then indicate favorable conditions for supergene enrichment in a primarily acid environment?

Hows it all work? Can anyone steer me to good sorces of information or explain it real clear for me?
I suppose I need to read the disertation on basement chemistry again....

The area we will be prospecting next year is a group of sulphide ore bodies, mostly dikes and maybe a few chimeny's. Some of which seam to have formed under water and some perhaps not. We know that some precipitates are formed in thick layers of red iron tetroxide. But we are not sure what basic ph indicators we should be looking for aside from gypsum. Some of the precipitate is also formed in clays.
Officially the free milling gold is associated with a hornfelds halo surrounding the sulphide bodies

I am attempting to get my hands on a manuscipt that should shed some more light on the subject. But I'm hoping perhaps I can gleen some information from here in the mean time.

We are in the Western Cascades in Washington not much carbonates here that I am aware of. I recon the acidic material must come into contact with basalt then and that precipitates the material? If so then what other materials would form indicating a nuetralized acid solution?
Anyone know how that works?

 

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[motohed]

Ragnor , there was a time in my life I could of helped you asnwer some of these questions , but I had a major accident in 2003 with a major head injury . I find now simple sentence structure and spelling are sometimes hard . I have good days and bad days . I went to college four over 8 years for chemestry and geology and you would think it would be wrote memory , but it's just not so . I won't ever give up , but it sucks when you look for your keys for an hour and they have been in your hand with something else the whole time . I'm fortunate that travaling and my evey day things like gravel mining mechanic, etc . I still have .

 

[KevinInColorado]

Ragnor , there was a time in my life I could of helped you asnwer some of these questions , but I had a major accident in 2003 with a major head injury . I find now simple sentence structure and spelling are sometimes hard . I have good days and bad days . I went to college four over 8 years for chemestry and geology and you would think it would be wrote memory , but it's just not so . I won't ever give up , but it sucks when you look for your keys for an hour and they have been in your hand with something else the whole time . I'm fortunate that travaling and my evey day things like gravel mining mechanic, etc . I still have .

Good on you for being so tenacious ...and for contributing here even if it's hard sometimes! Glad to have you with us on tnet!!

 

[Goldwasher]

Water oxidizes the sulfides making sulfuric acid, gravity and time do the rest

 

[Dakota Sioux]

Ragnor maybe one way could be the shearing of a fault deep underground under extreme pressure and temperature that would provide a space for metamorphic decomposed water and quartz from hydrous rocks to form into solution with metals and gold. The solution would be forced upwards through the cracks and finally to a pressure and temperature that was low enough to precipitate it out. This is one possible way of vein deposition in addition to ph contact scenarios.

 

[rockbar]

Give this guy's videos a look.

 

[motohed]

I know one thing at some point that the acids become neutalized and that is where the gold will be found , I just can't think of the natural neutralizers at this point , sorry my mind comes and goes but if you can figure out the natural neutalizers , I would definately try to figure out these properties that will in the long run help you find the the gold and other minerals

 

[Ragnor]

Thanks man, may your clarity be restored.

I know one thing at some point that the acids become neutalized and that is where the gold will be found , I just can't think of the natural neutralizers at this point , sorry my mind comes and goes but if you can figure out the natural neutalizers , I would definately try to figure out these properties that will in the long run help you find the the gold and other minerals

 

[Ragnor]

Much appreciated, that's a very informative series.

Give this guy's videos a look.

 

[Alex Burke]

I think the "basic component causing the gold to precipitate" is a carbon bearing wall rock that reacts with the solution to make methane, this forms bonds and scavenges the gold out of solution, there are many types of carbon rich rocks as you know like shale for example. The gold could also drop out of solution from a large pressure drop. There are also other ways it gets deposited like Sedex etc but I think this is what you are asking about, possibly I don't understand this science super well but this guy does check out parts one and two of this series. He talks about carbon rich rocks and gold solutions at around 8min 30 sec in the second part of series.

 

[Ragnor]

Well I have recently become aware of the action of carbon rich materials in the precipitation of gold and it has piqued my interest. I have seen layers of shale in sandstone in the vicinity of a gold bearing stream in the area and I intend to investigate that further when the snow melts. I also have some carbon rich material I collected from a seam in sandstone from some distance away from that area. It just caught my attention so I collected it. I think I may have to burn some of that and see what's in it.
However, those types of deposits have not been mined historically in this area. What I am looking at here is more where very old intrusive bodies have been exposed to meteoric decomposition and mobilized downwards untill they interact with 'somthing' that will cause rich secondary enrichment. Pocket gold. The saving grace of my particular area is that the primary deposits have been leached making the primary ore spotty and not commercially viable. Gold in quartz or even calicite he is 'almost' unheard of. However, if one can find layers where the leached materials redeposited, well, that would be a good day. I'm working on understanding that chemistry. The information you guys are sharing is definately helping and I appreciate it. Keep em coming

I think the "basic component causing the gold to precipitate" is a carbon bearing wall rock that reacts with the solution to make methane, this forms bonds and scavenges the gold out of solution, there are many types of carbon rich rocks as you know like shale for example. The gold could also drop out of solution from a large pressure drop. There are also other ways it gets deposited like Sedex etc but I think this is what you are asking about, possibly I don't understand this science super well but this guy does check out parts one and two of this series. He talks about carbon rich rocks and gold solutions at around 8min 30 sec in the second part of series.

 

[motohed]

I think , I would try to crush the material rather that burn it , Carbon burns hot and you may melt other materials into the gold , not that it is bad but it will be more steps to retrieving the gold

 

[Ragnor]

I think , I would try to crush the material rather that burn it , burns hot and you may melt other materials into the gold , not that it is bad but it will be more steps to retrieving the gold

Here is the carbon/sulphide material I collected. It's probably been laying out behind the barn for 12 years now. I think somone told me to look for dark colored rocks or somthing and these looked very out of place. Don't know if I can even rememeber where they came from now. But they are several miles from the main ore body, so who knows.

 

[nadavis]

Good topic. I have a group of hardrock mines, with what seems to be a large debris type placer in the valley right below. The gold in the quartz all seems to be very small and fine and mostly but not all free milling. The gold in the placer below is frequently a lot larger and also is porous. I have been wondering if it could be a type of supergene origin the source being a solution of sulphides leaching out of the mines above and precipitating the gold out when it comes into contact with ? I was looking at a piece with a loupe recently and could clearly see the gold stuck to some black stuff, almost forming around it. At the time I was thinking the black stuff was maybe magnesium, but now I am thinking it looks a lot like those dark rocks of yours. If I put a drop of hcl acid on it would it react if it was a carbon material? any other way I could verify if it is carbon based?

 

[Ragnor]

Good topic. I have a group of hardrock mines, with what seems to be a large debris type placer in the valley right below. The gold in the quartz all seems to be very small and fine and mostly but not all free milling. The gold in the placer below is frequently a lot larger and also is porous. I have been wondering if it could be a type of supergene origin the source being a solution of sulphides leaching out of the mines above and precipitating the gold out when it comes into contact with ? I was looking at a piece with a loupe recently and could clearly see the gold stuck to some black stuff, almost forming around it. At the time I was thinking the black stuff was maybe magnesium, but now I am thinking it looks a lot like those dark rocks of yours. If I put a drop of hcl acid on it would it react if it was a carbon material? any other way I could verify if it is carbon based?

This is what I found and didnt find any alternatives. Knowing myself, carrying a bottle of HCL in my backpack is a very risky proposition.

The "Acid Test" for Carbonate Minerals and Carbonate Rocks

 

[Ragnor]

I think , I would try to crush the material rather that burn it , burns hot and you may melt other materials into the gold , not that it is bad but it will be more steps to retrieving the gold

After thinking about this for a while. I believe this material has to be burned in order to reduce the water soluable salts back to a metalic form.

 

[Ragnor]

Well I been crushing it in a fence post driver. The ugly carbon yields Metal! I'm frickin' Stoked! LOL. The first batch was cross contaminated but there was a crushed piece of wire gold that I had never seen before. The second pan doesnt have any pure gold but has lots of sulphides and what I'm hoping is pgm's. It's silver colored with a smear of gold on the surface. When I get a good batch of it I'll post some pics.
Had that stuff laying around all those years, lol.

 

[Ragnor]

Well , sorry about the dodgy quality of these images. It's hard to photo through the microscope clearly. This stuff is very small.
I'm guessing the primary material is silver due to the black oxidation and the stick like structure of the crystals.

These images are at 300X





Images are after a 10 minute soak in vinegar to brighten it up.

 

[Ragnor]

Not quite focused but I recon it shows well enough.



I repanned the material and found these.

 

[motohed]

This is what I found and didnt find any alternatives. Knowing myself, carrying a bottle of HCL in my backpack is a very risky proposition.

The "Acid Test" for Carbonate Minerals and Carbonate Rocks

Thanks for the link to the Geology site Ragnor !!!!
I will also say wear a good quality resperator as Carbon can be almost as bad ,as Aspestus for the lungs when your crushing it . The cheap paper masks just won't do .