What's the best way to seperate Pyrite from gold?

[eagle2]

Any kind of liquid soap.

On the sulfide ores, after roasting, try a leach of Sodium Sulfide or Thiourea.
To get info there are references here on the forum or Google these keywords.

 

[Shecker]

I use to have a mine in which all of the gold was in pyrite. I would roast the ore using only the heat of a campfire. This drives the sulfur off from the pyrite and turns it into magnetic iron. A magnetic separator would yield a clean pyrite concentrate and I would dissolve the iron with H2SO4. Just A thought.

Randy in Gunnison

 

[Irons]

Smitty,

Listen to Irons about arsenic poisoning. The initial poisoning is bad enough. Years later I had the lower half of my right ear surgically removed at the age of 42 because of basal cell skin cancer attributed to arsenic in my system. I was the youngest guy the V.A. had ever seen with this form of cancer at the time. My nose will be next. I have other tumors on my face and behind my right ear and shoulders etc. It's not fun being disfigured because of this stuff. Respect this material! Especially if you use a crusher or hammermill to pulverize this material making it easier to absorb it through your skin.

My exposure to arsenic was due to the negligence of the Penwalt Chemical Corp in Bryan, Texas on Finfeather Rd. The rather large sum of money I recieved in settlement is of course long gone but the cancer remains.

Sincerely,
Wayne

Wayne is right. Always assume that Pyrites contain Arsenic. Even ones with no precious metal content will have some. The question is how much. Hot HCl will generate AsCl3 which is volatile on heating. Arsine is another volatile Arsenic compound. One good breath of it will kill you.
If you find a promising Sulfide deposit, send a sample to an assayer like Acme that can tell you
what the Arsenic content is. The lowest concentration I've seen in these parts was 35 PPM. Not much but still very dangerous for long term exposure.

You may get away with it for a long time but then like me, get a sample loaded with it and that one will get you.
Arsenic poisoning is very painful and you will have no doubt you've been poisoned, especially when your urine starts looking like tomato juice. It hurts.

 

[Rag and Bone]

Has anyone heard of gold in Pyrite from the midwest? Northern Wisconsin to be more precise. I found a source.

Irons, you must be one tough dude. I hurt just thinking about what you said.

 

[Oz]

Irons,

If you roast your black sands and pyrite to a red heat and hold it there for 5 or 10 minutes will you have destroyed the toxins so it is safe to proceed with chemical dissolution with out poising yourself? It would be simple to make a rig for roasting ores that would be safe to leave out unattended.

 

[Oz]

Agreed Rag and Bone! No amount of gold is worth me peeing tomato juice. Just not that tough! :shock:

 

[calgoldrecyclers]

Oz,
pyrite is not an arsenic ore. arsenopyrite is. also orpiment. and realgar.
identifying the two is fairly simple with easy to do tests. pyrite streak is greenish black, while arsenopyrite is dark grey to black. specific gravity of pyrite is 5.1, while arsenopyrite is 6.1. arsenopyrite hardness is 5.5 to 6. pyrite hardness is 6 to 6.5.
pyrite when struck with a hammer, sparks, and gives a distinct odor of sulphur ( freshly struck match ). arsenopyrite when struck with a hammer, gives off a smell of garlic.
pyrites fracture is conchoidal ( like how glass breaks )
arsenopyrites fracture is uneven.
arsenopyrite and pyrite are different in color. arsenopyrite is a brassy white to grey, pyrite is brassy yellow.
hope that dispells any dangers in roasting pyrite.

 

[Lou]

Has anyone heard of gold in Pyrite from the midwest? Northern Wisconsin to be more precise. I found a source.

Irons, you must be one tough dude. I hurt just thinking about what you said.

That's why he's called "Irons"--tough as iron


Roasting it is probably the best way to remove the sulfides and make SO2 out of them. Heck, you can even run the SO2 into NaOH water and make some sodium sulfite.

 

[Oz]

Calgold,

That is great information about the different ores, the problem from my point of view is that all the iron sands I have pulled out of waterways are a mixed lot and of small size. If I was hard rock mining it would be effective testing as you suggest. I even have a reddish pink iron sand I get in one area that will evenly mix in stratifying with your more traditional black sands.

Because of these mixes I am trying to find out what effect the roasting has on the cyanides. I prefer to treat all iron sands as suspect, so I don’t get a “gift” like Irons did.

 

[calgoldrecyclers]

Oz,
ahh yes. the black sand dillemma. i save everything that i cannot recover and send it off to a smelter to be processed. you know, the micron gold. 400,000 plus colors per ounce. i have seen various methods for recovery of flour and micron gold, but few if any actually work. this is where refining with acid comes into play. unless, you know alot about the hazards and dangers, and are proficient in refining, i would leave it to the refiners. thats what they know. prospecting is what i know.

when you said you find a reddish pink material in your black sands, is it more reddish than pink? more pinkish than red? a metallic substance? or more like a silicon? i have found more than not that garnets, tourmalines, rubies, and proustites are littered in amongst the black sands. because the specific gravities are identical, i guess.

have you tried looking at your black sands through magnification? a strong light pointed towards the source helps. what may look like a grain, actually turns out to be a crystal and so forth.

what do you mean by "cyanides"? do you suspect there to be cyanides intermixed in the black sand?

 

[Oz]

My bad, I misspoke saying cyanides I meant arsenic. Cyanides are killed even with regular cooking (as in food) temperatures if I remember correctly.

“when you said you find a reddish pink material in your black sands, is it more reddish than pink? more pinkish than red? a metallic substance? or more like a silicon? i have found more than not that garnets, tourmalines, rubies, and proustites are littered in amongst the black sands. because the specific gravities are identical, i guess”

In my dreams! I have found a few odds and ends like that in other areas but am not a gemoligist like you. Let me tell you about the area; there is an old abandoned mine that I go into that is literally a mountain of near solid hematite/magnetite, I can get solid pieces as big as one wants. There is some oxidized copper here and there as well and some magnetite with small gold iron pyrite crystals.

Now 10 minutes away at my girfriends house is where I found the reddish/pink sands. Her yard is littered with boulders that are a red sandstone material with river worn quartz in the matrix. Oddly enough there are almost no black sands present here. Last weekend I took a quick sampling using a pie tin of all things, this weekend I will be bringing my screens and pans and see how it classifies with riffles.

Of note; her driveway was restoned with stone from a local rock quarry. It is a 30% grade so after 6 months of storms I panned some concentrates from the bottom of the hill and found 3 flea bite pieces of gold.

 

[calgoldrecyclers]

Oz,
it sounds like you might have found gneiss. is it banded? or more like granite? if its gneiss, you wont find any gold with it. if its granitic you have a much beter chance. quarries rarely are aware of striking gold. or a gold vein for that matter. they are interested in the rock and thats about it.
good luck and happy hunting!
Ezra

 

[Oz]

Not even close, I hope I have my camera with this weekend and will take a picture of a representative rock at her place. This is what I saw in googleing “gneiss” and why I think it is not it. what is here is not banded at all.

http://en.wikipedia.org/wiki/Gneiss

 

[calgoldrecyclers]

Oz,
O.k. well that sounds promissing. are they fairly large boulders? or is it more like river gravel (2 1/2" diameter rocks)? little black specks littered throughout? could be a feldspar biotite. (good indication of minerals present) unfortunately, the soil in and around the areas of houses, usually dosnt come from that area, it is usually shipped in on dump trucks. but, you can be pretty sure it came from somewhere in that area.
do y'all have horsetails out there? a type of fern that grows out in the woods. google a pic. i have heard that horsetails contain gold. 610 grams for one ton of horsetails. wet weight or dry, i couldnt say. i would guess that you dry and incinerate then process the ashes. you could ceratinly gather a ton a week, not a bad haul at todays prices.
well, let me know if you obtain a pic, im a little intrigued to know what it is.
have a good weekend, i'm headed out to my claim.
Ezra

 

[calgoldrecyclers]

Rag and Bone,
if you have found pyrite, it is a very good indication of gold present. it would be processed as a by product, but gold no less. whenever you find minerals such as calaverite, krennerite, sylvanite, quartz and pyrite, it is a very good indication. just remember, gold is not always the buttery yellow people envision in their minds. depending on the associative minerals and gangue, gold can be tinged red, black, green, silver, brown, reddish brown, etc. gold now adays is processed as a by product of coper, silver and lead ores. with the occaisional open pit, large heap, cyanide leach, micron gold processing. about three percent nationwide, comes from placer deposits.

when you're out and about, look for copper ores and their associative minerals and scheelite (tungsten) sperrylite (platinum) iridosmine (osmium) but, be careful if you do come across iridosmine, it is poisonous. worse than large doses of arsenic. it is the osmium content that makes it unstable.
it will more than likely be found in grains and flakes in your black sands.
osmium being the heaviest mineral. SG of 22.5.

according to my copy of a range guide to mines and minerals, looks like you are in copper country. excellent opportunity for specimen hunting on the old tailings piles.

if you are looking to understand and identify what you are looking for, i suggest finding and reading a copy of De Re Metallica, by georgious agricola, written in 1557. they have reprinted copies translated into english that wont cost more than twenty or thirty bucks.
it is definitely a good read.
hope that helps a little,
Ezra

 

[Oz]

calgoldrecyclers,

Here are a few pics. This is not locally quarried stone brought in by a developer building houses, only the driveway is imported. The yard is littered with this kind of stone making up over 70% of the “soil” by volume, some as big as a truck. There is a 10 foot wide stream at the bottom of the property and a 30% grade leading down to it the whole way. Any input would be welcomed.

It looks as if it might quit raining so I am off to the iron mine with a new eye to other minerals.

 

[calgoldrecyclers]

Oz,
looks like a sandstone conglomerate. it should break and chip off rather easily with a pick axe. the blocky looking rock in the foreground of pic number two, looks like ironstone. a copper bearing gangue material.
what you want to look for is granite with interdisspersed flecks of a lightish grey mineral. limestone replaced by quartz, and so on. any igneous/ metamorphic rock you can find. smack it apart and notice how the rock fractures. pay close attention to the mineral where the rock has fractured. you will need a loupe to get a good look.

looks like they may have been poison ivy in pic number one, watch where you step!
that stuff is like the plague to me.
good luck on your many ventures and happy hunting!

 

[Oz]

Calgold,

Ignore the file name these are under. These are not the greatest pictures for color and it was getting dark when taken. These are not representative of the stones found in the iron quarry they were hand picked from a mountain of overburden tailings that are piled up against an exposed rock face of solid magnetite several hundred feet tall. They are predominately green.

In the first picture you can see some of the copper has oxidized from a green to a blue around the iron pyrite crystals (upper cluster) and the lower cluster of coppery colored crystals.

The second picture shows the green at the bottom transitioning to a silver colored crystalline structure with a small core area of crystalline hematite? Forgot my magnet.

The last picture has bands of dark metallic crystals with the right side cleaved showing the iron face in the green stone.

There are also some stones that are a purer green that tend to be crumbly. This is just 10 minutes away from the sandstone pic location where the stream yields virtually no black sand. The geology is all shifted around here. There is also one of copper colored fine banding in it. I would love to hear your opinion on these 3 pics as you seem to know more than I and I am just guessing on some parts.

I wish I had more time there but it is now posted, closed off and patroled by the local police. They gave me an escort away. Its too bad as it is a neat area, I did get the new owners name from the officers and will attempt to get written permission to visit again.

 

[calgoldrecyclers]

Oz,
that greenish looking gangue looks like granite, or perhaps limestone.
i would suggest breaking off a couple of chunks where the fissures/ veins are and crushing the samples. then you can pan out the samples. from the pics, looks like it may be pyrite, bornite, and perhaps carrolite.(light silver color) often, the presence of pyrite, is an indication of gold within the same host rock or gangue.

the smaller bands of green, to me, indicate a presence of copper.
a malachite type of oxidataion. perhaps chrysocolla.
do you know anything about the area? was it a mining district at some point?

as to the large boulders at your friends house, chip off what you can, grind the samples and pan them out. i suspect you may encounter values.
look for a geological survey for the area you are in. i think that will give you a better idea. it is hard to tell what something is from a picture.
is the material fairly weighty?
more so on one end than the other?

let me know what you find out.

 

[Anonymous]

If the gold values are not locked up in the pyrite simply screen the material down to a fine particle size. Mortar the oversize until it clears the screen and run in a spiral wheel. I usually do this twicw with a steeper angle on the second pass. Remove the magnetic sand with a magnet. Then clean with muriatic acid.................Bob