Auriferous Pyrite?

[theblade]

I’ve been doing a lot of research about past mines in the area where I live, the slate belt of NC. Basically all gold around me is in quartz with varying properties and surrounding rocks.

The closest mine however, about 1.5 miles away, I finally found after tons of reading was quartz with auriferous pyrite. The mine itself was a 6 foot quartz vein that they mined for about 2000 feet.

I found the rocks below a while ago and have been trying to determine what they were and if it was worth investing more time into seeing if gold is in them and if so if digging more is with it.

I wanted to get others opinions on if they thought these rocks could be auriferous pyrite. This is only a small example of what is in the area.

 

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[OreCart]

There is a saying in farming, "It is just a guess, unless you test!" And that is true in mining.

The old duffers did not dig out the shovels and picks and dig for 2000 feet without getting something out of it, and a simple assay, thou rather expensive, will tell you for sure. Even then it will only tell you total gold, and not "free gold".

But it would be silly to start something based on a single assay. Through a host of them, a determination of feasibility can be understood. It starts by taking a good sample, and not "salting the sample" just to get an indication of gold, but what real world situations will be like.

After that, there are laboratories where you can send in your crushed ore and they can determine what the best method is to get as much of the gold as possible. It is expensive, but not as expensive as getting all set up and realizing the envisioned method of extraction, primary crushing, secondary crushing, recovery and smelting did not work with your particular type of ore.

Alternatively, you can find someone with the type of recovery method you envision using; wilfrey table, miners wheel, etc and send an ore sample to them and see what the percentage of recovery is. In that way, you know BEFORE You invest in a method you later find out does not work well enough.

A lot of variables come into play, but you will need roughly 1/2 to 1 ounce per ton of ore of recovered gold to make it all worthwhile.

 

[winners58]

Auriferous just means a deposit, usually mixed with heavy minerals, is there gold in the pyrite? a lot of times there is.
a lot of old mines were worked for the free gold, crush, rod mill, shaker table. other ore's need processing,
leach, roasting, flotation etc... You can hi-grade and have an inexpensive assay done for just the gold/silver content.
look for the tailing piles sometimes they can still have gold the old-timers left behind.
https://www.greatfallstribune.com/s...pays-millions-gold-dug-mine-dumps/1794109002/

 

[Clay Diggins]

Auriferous means "gold bearing rock". If there is gold in the pyrite it will be finely divided free milling gold. Generally recovery is difficult with poor returns when the gold is contained in the pyrite but there are notable exceptions.

Most of the producing mines in North Carolina were worked before 1850. After 1850 the richness of the gold bearing ground in California pretty much put the eastern gold mines out of business. Gold was very hard to come by in pre 1850 America so the North Carolina and Georgia mines were the best thing going and could be profitable. Not so much after 1850.

If the mine was still in operation into the 1850s and later it probably produced good paying ore. If so just crush the ore to a fine powder and carefully pan the result. If there is gold it will be very small.

Heavy Pans

 

[Terry Soloman]

...

 

[theblade]

Auriferous means "gold bearing rock". If there is gold in the pyrite it will be finely divided free milling gold. Generally recovery is difficult with poor returns when the gold is contained in the pyrite but there are notable exceptions.

Most of the producing mines in North Carolina were worked before 1850. After 1850 the richness of the gold bearing ground in California pretty much put the eastern gold mines out of business. Gold was very hard to come by in pre 1850 America so the North Carolina and Georgia mines were the best thing going and could be profitable. Not so much after 1850.

If the mine was still in operation into the 1850s and later it probably produced good paying ore. If so just crush the ore to a fine powder and carefully pan the result. If there is gold it will be very small.

Heavy Pans

Thanks really good to know! The mine actually opened in 1896 and was reopened in 1933 until it flooded, one report from 20-30 years ago mentioned it could still be a viable mine. So I imagine they must’ve produced a decent amount of gold from it, especially to dig 2000 ft worth of tunnel for it.

The rock I have is NOT from that mine. I am going to try and find some trailings to see if what I have is similar to what was there. Unfortunately the area where I live is undergoing massive development and very little of these old mines and the land they were on are or will be left. A recent road project even noted some of these mines saying there was no reason to preserve them as there was no historical significance, so they just get paved over....

I’ll try and get a dolly pot made or piece one together and crush and pan out what I have and what I find from the old mine and let you know.

 

[smokeythecat]

There is probably gold in it. With that said, you will need to crush and smelt some. Having a professional do an assay on it would e even better.

 

[OreCart]

Thanks really good to know! The mine actually opened in 1896 and was reopened in 1933 until it flooded, one report from 20-30 years ago mentioned it could still be a viable mine. So I imagine they must’ve produced a decent amount of gold from it, especially to dig 2000 ft worth of tunnel for it.

The rock I have is NOT from that mine. I am going to try and find some trailings to see if what I have is similar to what was there. Unfortunately the area where I live is undergoing massive development and very little of these old mines and the land they were on are or will be left. A recent road project even noted some of these mines saying there was no reason to preserve them as there was no historical significance, so they just get paved over....

I’ll try and get a dolly pot made or piece one together and crush and pan out what I have and what I find from the old mine and let you know.

One thing to keep in mind is, back in the old days, they had to mine about 1/2 an ounce of gold per day to be profitable. Today we can mine a considerable less; but it depends on your lifestyle of course.

 

[theblade]

I’ve got a dolly pot being made that will be ready next Monday or Tuesday, so I’m hoping to get a good amount of this rock crushed. In the meantime I rigged up a little area to crush some small pieces. I crushed a piece about the size of a golf ball just to get an idea of what’s in these. I couldn’t crush it all because the base broke off and I lost some dust but nonetheless it was enough to see just how loaded with pyrite these rocks are. I dont think there is any visible gold in this pan, but the pan sucks so I’m getting a new one. If the pans look like this after crushing more rock I will get an assay. My worry is there’s a decent amount of gold, but locked up in pyrite.

 

[theblade]

Well I stopped by a prospecting shop today to look into a few supplies and advice. After showing them my rocks he became very interested and pulled out his MD20 to check. I brought a few rocks smaller than a fist and they ping gold all over them. He had a card to make sure it was calibrated and every area he touched went off going towards the rock and not pulling away. Wish I had the dolly pot today now but once I get it crushed and panned I am going to borax heat it in a crucible to see what I can come up with and will let you all know.

 

[arizau]

I’ve got a dolly pot being made that will be ready next Monday or Tuesday, so I’m hoping to get a good amount of this rock crushed. In the meantime I rigged up a little area to crush some small pieces. I crushed a piece about the size of a golf ball just to get an idea of what’s in these. I couldn’t crush it all because the base broke off and I lost some dust but nonetheless it was enough to see just how loaded with pyrite these rocks are. I dont think there is any visible gold in this pan, but the pan sucks so I’m getting a new one. If the pans look like this after crushing more rock I will get an assay. My worry is there’s a decent amount of gold, but locked up in pyrite.

Your pan is not the problem IMO. As was mentioned in a post above, if there is any free milling gold associated with the pyrite it will likely be tiny. The best way to pan for tiny gold particles is to screen and pan it separately by batch of only like sized particles. What you may find by screening is that the gold is smaller than 50 mesh and likely smaller than 100 mesh. Mixing just those two sizes (actually three since there is also minus 100 mesh), not counting anything larger, reduces the chance of being able to retain the minus 100 mesh gold in the pan.

Good luck.

 

[OreCart]

There are lab's that will take your ore too, and run it through various devices and determine what the best method is for extracting the most gold for the least amount of work.

It is a pricey test, but far cheaper to pay for that, then get all geared up in a particular set-up and realize it does not work well.

I am a HUGE fan of micro-mining, but also believe we must follow what big mining does too. That means doing a lot of testing and exploring before making the jump to actively mining.

My goal now is to find the best possible vein, then assay it, and determine if I can make a go of it. I freely admit I am scared to invest in quarrying, crushing, separating and smelting, right now, but it is why I am going to trench across some of my property (like the big mines do) and see what is there. That will give me a sense of vein frequency, width, and length. Assay's will follow; all before investment.

 

[theblade]

Your pan is not the problem IMO. As was mentioned in a post above, if there is any free milling gold associated with the pyrite it will likely be tiny. The best way to pan for tiny gold particles is to screen and pan it separately by batch of only like sized particles. What you may find by screening is that the gold is smaller than 50 mesh and likely smaller than 100 mesh. Mixing just those two sizes (actually three since there is also minus 100 mesh), not counting anything larger, reduces the chance of being able to retain the minus 100 mesh gold in the pan.

Good luck.

Thanks and yea I agree the pan isn’t the problem. Stated that more so because the pan is tiny and so scratched up it’s hard to tell what’s what since so much stuff gets stuck in the grooves. Hard to tell from the pics how bad it is.

I did get a new pan from the place I stopped by yesterday which is much better. Have items coming Monday to smelt the gold with borax. So, hopefully next Monday or Tuesday I can get a decent amount of rock crushed and panned and then smelt it to see how much gold there is. With how much the MD20 was going off on the rocks, I’m hoping there’s a decent amount in them.

 

[theblade]

Yea trenching I have done in my yard has helped show the rough area of the vein. I know it goes from SW to NE, which is typical in this area for veins. The big question for me will be how deep it goes. Many areas around me followed these veins down to 100’ and the veins at times were several feet thick. So much of what I have found is surely just some loose rock that’s come up closer to the surface and not even the main vein itself.

 

[theblade]

So the welder is running behind so I don’t have my dolly pot yet. I’m building the mini metal furnace though so it’s ready once I do have the dolly pot.

For fun here is some eye candy of a rock I found in gravel I bought for a French drain.

 

[OreCart]

Yea trenching I have done in my yard has helped show the rough area of the vein. I know it goes from SW to NE, which is typical in this area for veins. The big question for me will be how deep it goes. Many areas around me followed these veins down to 100’ and the veins at times were several feet thick. So much of what I have found is surely just some loose rock that’s come up closer to the surface and not even the main vein itself.

Yeah quartz is funny because of the way it forms. I got veins of the stuff running in bands 20-40 feet apart, but a lot of it is disseminated quartz too. The does not guarantee gold, but it does increase the chances that the host rock having it.

In my gravel pit I got an outcropping of bedrock, and it has both a vein and disseminated quartz. I also found some galena while digging out a load of gravel which was an interesting find.

 

[theblade]

Mini metal foundry is done. Letting it cure, then will glaze my crucibles and hopefully have a dolly pot next week to finally crush some rock and see what’s inside!