Black sand pyrite sulfides and gold

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im1badpup1

Well-known member
Joined
Oct 25, 2017
Messages
90
Hi everybody im new to the forum and prospecting. A quick history of myself is ive a long term interest in geology mineralogy and a practising amateur chemist over the last 20years. It doesnt mean im smart or educated though.

Anyway i was recently hunting minerals corundum and garnet and came across an alluvial blacksand deposit. Ive never panned before but took a sample home and panned with a enamel pie tin and lo behold found small and microgold20171015_131321.jpg

An idea of scale i put a flake on my fingernail hereView attachment 120171020_093129.jpg

Theres small lead particles also present at the bottom of the pan with the gold.

Ive tested to be sure and it is indeed gold

Ive ordered a goldcube to seperate the free gold for now.

Ive been studying the other material in and around the alluvial black sand deposit and theres more of interest..

Theres a lot of sulfides. Pyrites etc. Both hydrothermal vent deposits and free ore released from vein deposits by weathering. I really could do with some direction in whats the best thing to do with these. In processing them. And the black sand concentrate. Il elaborate on this with some pictures of minerals and streaks in next post
 
I took a sample of heavy minerals within the black sand layer. The rocks vary in colour mainly grays reds green hue. Almost all are very very dense. I streaked 100 or so for further clues. Ive a multitude of colours from dull blacks lustrous all the way to dull gray and shiny grays. Some red streaks n browns. Ive some what have a yellowish streak too. I cant see with a magnifying glass any gold particles in there.
I broke some rocks open a few days ago. A lot of sulphurous smells and sparks. Some had a very distinct acetic acid smell instead. Vinegary. Now ive attached a pic of sample mineral rocks streaks and the inside of them after splitting. Some have dulled a lot since breaking as they was almost entirely shiny i side but theyve left highlighted shiny sparkly silver veins not particularly visible when i first split them.
20171029_085318.jpg

Originally i intended to seperate the samples before testing further but in practise yes i could the larger rocks but id be dealing with tons later on pea gravel size so excepting a magnetic itd be very difficult to seperate the majority of smaller sulfide pyrites or whatever they are out.

I researched best as i could the origins of the alluvial material to find relevent data indicating the precious metal contents. This is where i start to get lost and advices would be welcomed.

For example the sulfides in the area of origin have been assayed extensively throughout and ppm reading vary hugely for gold. Its unclear to me when they have stated "an ore sample was taken from quartz vein 6m wide comprised of 5 to 8 pcent sulfides with a ppm value returned of 50ppm of gold present within the sulfides" does this mean the sulfides plus the quartz vein are included in the calculation ppm?

Some facts im certain of when trawling through literally hundreds of research geological documents is the sulfides dominate here in my case as a source of gold. But theyre not the source of the freegold i panned. that source has never been scientifically verified. But the values in sulfides ranging from a few ppm to in exceptional cases over 1800ppm and the confusing ppm calculations ive seen over gold content im interested in exploring the sulfides further.

Is it generally a waste of time processing sulfides and is the usual process to go to the oxide via a roast then smelt or chemically extract at that point?
 
"Anyway i was recently hunting minerals corundum and garnet and came across an alluvial blacksand deposit. Ive never panned before but took a sample home and panned with a enamel pie tin and lo behold found small and microgold"

Is this alluvial black sand deposit along side of a current water source - stream, river, etc. Or is it a old high bank deposit from ancient water action?

Can you post a picture of the deposit?

James
 
im1badpup1 said:
I took a sample of heavy minerals within the black sand layer. The rocks vary in colour mainly grays reds green hue. Almost all are very very dense. I streaked 100 or so for further clues. Ive a multitude of colours from dull blacks lustrous all the way to dull gray and shiny grays. Some red streaks n browns. Ive some what have a yellowish streak too. I cant see with a magnifying glass any gold particles in there.
I broke some rocks open a few days ago. A lot of sulphurous smells and sparks. Some had a very distinct acetic acid smell instead. Vinegary. Now ive attached a pic of sample mineral rocks streaks and the inside of them after splitting. Some have dulled a lot since breaking as they was almost entirely shiny i side but theyve left highlighted shiny sparkly silver veins not particularly visible when i first split them.
20171029_085318.jpg

Originally i intended to seperate the samples before testing further but in practise yes i could the larger rocks but id be dealing with tons later on pea gravel size so excepting a magnetic itd be very difficult to seperate the majority of smaller sulfide pyrites or whatever they are out.

I researched best as i could the origins of the alluvial material to find relevent data indicating the precious metal contents. This is where i start to get lost and advices would be welcomed.

For example the sulfides in the area of origin have been assayed extensively throughout and ppm reading vary hugely for gold. Its unclear to me when they have stated "an ore sample was taken from quartz vein 6m wide comprised of 5 to 8 pcent sulfides with a ppm value returned of 50ppm of gold present within the sulfides" does this mean the sulfides plus the quartz vein are included in the calculation ppm?

Some facts im certain of when trawling through literally hundreds of research geological documents is the sulfides dominate here in my case as a source of gold. But theyre not the source of the freegold i panned. that source has never been scientifically verified. But the values in sulfides ranging from a few ppm to in exceptional cases over 1800ppm and the confusing ppm calculations ive seen over gold content im interested in exploring the sulfides further.

Is it generally a waste of time processing sulfides and is the usual process to go to the oxide via a roast then smelt or chemically extract at that point?

Are any of the samples in your picture, or any of the heavy minerals within the black sand layer, magnetic?

James
 
"Ive ordered a goldcube to seperate the free gold for now."

Good choice. IMO, a three stack model is sufficient.

Are you going to use it on site of the deposit? What will be your water source? Even if you set-up as a self-contained operation, you have to get a fair amount of water in there in the first place to set it up.

Have you screened any of the black sand to determine the most common grain size? The pics of your samples used to create your streaks appear to be rather large.

James
 
20171029_135530.jpgHi james ive a neodynium in the post with my goldcube. I dont have one to check but... i tried my ctx3030 detector and pinpointer probe and had no signal. The small gray lead and gold gives a signal. None of the sulfide rocks give any signal at all.
Ill post tomorrow on magnetic results its at postoffice to pickup i missed delivery thats all.

The blacksand deposit theres a very fine and dense sand in the pan at the end with the lead and gold. It kind of sets or cements and only pans off in really thin layers. I get some small sulfide pea size in this. The rests black sand lead n gold. On top of that a coarser black sand layer i think is something else n i suspect if anything thats magnetic. Eg iron oxide. Im not an expert on the geology but the chemistry i can tell its a different material. Density. Texture. Coarseness Its behaviour been manipulated. in comparison.

Ill post you a picture or several if you like of the black sand deposit in the next few days when im back there.

About the sulfides. Ive seen massive erratics certainly a few 100kg in size and think theyre hydrothermal in origin. But theres certainly sulfides from volcanic veins and metamorphic origin too. Some still have mother rock on them i can identify as been from a specific area. Theyre far smaller not many have cubic crystalline structures. Some are globular.
 
Ive just pyrolyised a small piece of one of them larger rocks it gave off a sulpurous smell and left me with redbrown oxide plus tiny unknown prills of a metal. To be fair it may of come off the stainless spoon im not 100%

Ive worked with some materials in the past n have to hand a number of things what will help i think.
Ive the equipment and competence and mercury too hand. Ive worked with making salts of mercury and postreaction recovery of spent hg to recycle so oxidation of sulfides and mercury extractions one way to go.

Ive worked with hypochlorite and TCCA too doing hoffman degradation elimination and reaŕrangement so adapting to a recovery method along this route wouldnt be a bad thing. I dont think no one here who experimented along these lines knew the mechanism of action in naocl -hypochlorite solutions is also controlled by temperature. I worked in cold conditions to favour a particular mechanism temperature control had to be within 2 degrees 12c the hypochlorite was more problematic and prolonged but TCCA swift and convenient. Im going to try a chlorination on some gold flakes and see where i get the desired result conditions from and too.

Ive made sodium and potassium cyanides before but id rather not its.not a synthesis i like. I can probably make any chemical i cant acquire. Ive access to smelting equipment n ive a adjustable amp n volt electrolysis kit..

I did have kindof a plan but because i have an erratic deposit with a mechanically unsortable material mix im unsure how to run the full route.
Sulfide>oxide>smelt>AR>displacement?
Sulfide>oxide>hg extract/chlorine route..
 
"I really could do with some direction in whats the best thing to do with these. In processing them. And the black sand concentrate."

I'm still a noobie on the chemical refine end. But, if I had a black sand deposit like that in front of me, I would be running what I could through the gold cube to densify. Screen the concentrates (even down to <100), separate the concentrates from any magnetics, and then pan the concentrates or run them on a Miller table.

The gold pan is a very cheap and wonderful analytical tool. Work on your panning skills - it's worth the time. I have seen desert hard rock miners use a gold pan with a small tub of water and analyze crushed ore samples to see if the samples are worth further analysis with a assay test.

Speaking of crushing - I would be running the larger pieces through a hammer or ball mill and repeat the panning or assay tests on them. You could also use a dolly pot on site to crush the ore down to more manageable sizes.

Of course, all of this is dependant on the size of your deposit and the amount of time you want to invest. From the looks of your panned sample, I would be chasing the free gold first.

James
 
Thanks james yes the freegold n cubes going first.
Ive a second heavy metal in with the concentrates 20171030_111134.jpg

The dull gray material. Looks like lead but could be zinc i guess too. Looking closely theres a third soft gray metal in there too.
The golds been removed with mercury im going to retort this too theres some mercury contamination still.
Some of the heavy material near the end of the pan with the concentrates in this pic20171030_111258.jpg
 
im1badpup1 said:
Thanks james yes the freegold n cubes going first.
Ive a second heavy metal in with the concentrates 20171030_111134.jpg

The dull gray material. Looks like lead but could be zinc i guess too. Looking closely theres a third soft gray metal in there too.
The golds been removed with mercury im going to retort this too theres some mercury contamination still.
Some of the heavy material near the end of the pan with the concentrates in this pic20171030_111258.jpg

That's the strangest looking concentrate I've ever seen. But, my black sand cons experience is only from my years of gold dredging within the rivers of California's mother lode regions.

Why the use of mercury in your gold panning efforts? The pic you posted of the free gold found in your first panning efforts certainly were large enough for easy retrieval. Please tell me you have past experience with mercury and retort use and that you are aware of its toxicity issues.

When you say you are going to retort this too, are you saying that you plan on putting all of your cons in your retort or just the pregnant mercury you panned out? I certainly would not recommend retorting any other material until you know for sure what you are dealing with.

If there are small amounts of mercury left in your pan, just keep panning to consolidate any spattered mercury and then use a gold pan snuffer bottle to suck up the loose mercury.

James

stansport_gold_panning_snuffer_bottle_1298555_1_og.jpg
 
Yes ive used mercury before i used to make salts from it for chemical catalysed synthesis . Go from the elemental form to oxide or nitrate and or chlorinate. Recover the spent impure hg post reaction then redistill and reuse.
Ive all the glassware and equipment still. Its no problem for me to rig up gas generators either. Anhydrous hcl gas for example.
There was spots of elemental mercury in one area samples i took it made no difference to me at that point i was going to treat it all as contaminated so adding some i had made no real difference to me. Its sucked up all the pinhead size gold.
I was planning to heat the gray metal seperately to drive off any mercury contamination and collect any what does as thats what i first saw it on.
Sorry i forgot to post pic of the fine black sand concentrate i seperated il do it later. Ive panned through it three times to make sure i missed nothing.

Just to clarify
il retort the mercury
Then retort the gray metal to remove any residual hg coating
Mercurys going back in container afterwards.
would it be premature to dissolve the metals then recovered in aqua regis and use a displacemant to seperate each one according to reactivity?
 
cosmetal said:
"Ive ordered a goldcube to seperate the free gold for now."

Good choice. IMO, a three stack model is sufficient.

Are you going to use it on site of the deposit? What will be your water source? Even if you set-up as a self-contained operation, you have to get a fair amount of water in there in the first place to set it up.

Have you screened any of the black sand to determine the most common grain size? The pics of your samples used to create your streaks appear to be rather large.

James
What is a goldcube, please?. Thanks.
 
https://www.google.com/search?q=goldcube&ie=utf-8&oe=utf-8&client=firefox-b&gfe_rd=cr&dcr=0&ei=W4T4WZP8Bubk8Afx7YnAAQ
 
Pics of blacksand
Closeups
Shook the bloody thing flat n think any bits of lighter material has obscured the detail of the black concentrate. Il take some more if need be
20171031_024354.jpg20171031_025238.jpg

Ive never took or viewed closeup detail of sand before its beautiful lol.

Cuchugold-
A goldcube is an underflow sluice designed to take 1/8th or smaller material and concentrate it catching heavier particles in the pressure drop in waterflow the underflow current causes. And the vortex matting aka rough conveyer belt holds the material.
Its basically preset with correct flowrate and setup to go once prepped theres less mistakes you can make operating as a novice and from ppls testimonials its very good at its job.
 

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Thanks Goran. I got that too. What is the maximum capacity of this device?.
Also thanks im1badpup1.
 
cuchugold said:
Thanks Goran. I got that too. What is the maximum capacity of this device?.
Also thanks im1badpup1.
https://goldcube.net/

One of their drop down promos states "Tons to ounces in minutes."

Dubious claim at best (unless their counting the weight of the processing water :shock: ), but, it does move pre-sorted material fast. However, you are left with a cons that still has to be processed further by pan, table or blue bowl device.

James
 
Picked up my neodynium n52 magnet today and separated out the magnetics.
None of the large sulfide or ore looking rocks was magnetic.
Hardly any of the small upto 10mm sulfides are magnetic. Heres a pic of the non magnetic heavys the very largest is about 10mm ive seperated from the black sand concentrate.20171102_094849.jpg
Very little of the black sand i concentrated down by repeated panning was magnetic either. Less than 10% for definate.
Pic of the demagnetised black sand concentrate i recovered my gold from
Apoligies about pics been in wrong place i dont know why its happening its driving me nuts

Ive a couple kilos black sand and a couple kilos of the upto 10mm stones seperated. Id like to test them for unknown or hidden pms.
The black sand looks like it could do with been much more concentrated ill try to size it and classify down my cube should be here in the next day so ill run it through that and try adjusting flow to drop the heavys.

Do you think the stones upto 10mm in size are of a sufficient concentration to proceed with next step? I was thinking of grinding them down and roasting them to convert to oxides next.20171102_095308.jpg

Ive researched the geology of the area best i can and best guess is sulfides are mixed pyrite galena hametite theres a silver content in one and also zinc.
If i made the oxide. Demagnetised the residue. If i then added glacial acetic acid and extracted lead acetate iron acetate. Then extract with hydrochloric acid to remove soluble zinc hcl ?
Im trying to think how best to remove what i can and test to determine silver and what % if i can. And for now just a spot test to see if theres a gold content in the sulfides. Its only for a sample test.
 

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"Do you think the stones upto 10mm in size are of a sufficient concentration to proceed with next step? I was thinking of grinding them down and roasting them to convert to oxides next."

It is my understanding (from this board) that the roasting is a no-no without first knowing what exactly you are roasting. Need a fire assay first to detect nasties like arsenic, etc.
 
Ah ok cosmetal. I should read the guidelines. For a fire assay i could oxidise and reduce in one step. I guess its prudent in most circumstances to send it off and get a professional analysis. Yes theres arsenopyrite its a mix.

A clue of the gold source. What is this in the pic.. i see them ranging in size from microscopic to several mm. Is it a precipitation of elemental metal gold alloy with silver thats been caught in a crystal lattice or rather the edges of the crystal development. Ive seen hundreds if not thousands over the years but never one in situ embedded in anything. Sometimes there is a complete circle or ring of gold. Always there is a heavier thicker deposit on one side. I find them most often like in the pic with an incomplete ring. Theyre usually twisted up from movement.
20171105_042537.jpg
 
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