Wisconsin Driftless Clay

[amSteve]

My home sits on the edge of flood plains of the Black River not far from LaCrosse Wisconsin. Having come across some YT vids about flour gold finds in the driftless region I picked up on one of the traits that I know my property has - stratified clay beds at creek sides. I've picked up enough panning skills to have found 2 - count 'em 2 flakes of gold.

I only own about 6 acres but it has several fairly steep ravines with a number of springs of varying sizes. The springs converge to create a creek that flows something like 15 gallons per minute. One of these has cut thru a bank of clay and left exposed about 3 feet above the creek bed.

The research I've done has me understanding the potential here as follows...

• Low probability of nuggets.
• Flour gold sits at the top of the layer of clay and probably hasn't traveled very far
• Flour gold recovery by pan is not practical

I'm going to need to devise a way to probe each of the springs more systematically than i have so far and, if warranted, scale up (automate?) the recovery of flour gold.

As of this point my biggest question is the possibility that i'm not seeing smaller flakes -- one of the YTs shows a guy cleaning up using a miller table that, after collecting the visible flecks he's able to scrape the matt and produce a small pile of gold dust. Given the amount of sand i have here, that might add up to something worth something.

I'm also interested in learning about how to probe the still covered clay that sits under 20-30 feet of loom and sand. It's going to have to be an approach that doesn't include heavy machinery.

I'd be highly appreciative of any thoughts on those questions.

 

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[arizau]

My home sits on the edge of flood plains of the Black River not far from LaCrosse Wisconsin. Having come across some YT vids about flour gold finds in the driftless region I picked up on one of the traits that I know my property has - stratified clay beds at creek sides. I've picked up enough panning skills to have found 2 - count 'em 2 flakes of gold.

I only own about 6 acres but it has several fairly steep ravines with a number of springs of varying sizes. The springs converge to create a creek that flows something like 15 gallons per minute. One of these has cut thru a bank of clay and left exposed about 3 feet above the creek bed.

The research I've done has me understanding the potential here as follows...

• Low probability of nuggets.
• Flour gold sits at the top of the layer of clay and probably hasn't traveled very far
• Flour gold recovery by pan is not practical

I'm going to need to devise a way to probe each of the springs more systematically than i have so far and, if warranted, scale up (automate?) the recovery of flour gold.

As of this point my biggest question is the possibility that i'm not seeing smaller flakes -- one of the YTs shows a guy cleaning up using a miller table that, after collecting the visible flecks he's able to scrape the matt and produce a small pile of gold dust. Given the amount of sand i have here, that might add up to something worth something.

I'm also interested in learning about how to probe the still covered clay that sits under 20-30 feet of loom and sand. It's going to have to be an approach that doesn't include heavy machinery.

I'd be highly appreciative of any thoughts on those questions.

Panning for fine gold recovery....use screen classifiers to create batches of equal sized material from your bulk concentrate and pan them separately. When gold is approximately equal in size to the sands it is mixed with it is pretty easy to pan since it is about 5 or more times as heavy as the other individual particles. Go to the Gold Cube website and open and read the section on the Golden Rule classifiers. At least for now, I would select the Cleanup Pack. There are cheaper sets available but not as good as these....I have several different types.
Good luck!

 

[ConceptualizedNetherlandr]

Get a cheap cement mixer ( which might be a challenge with the new tariffs).

Elevate the mixer about 2 feet and secure it.

Fill with water half way. Take a measured sample, like 2 gallons material. Weigh it then feed it into the mixer as it spins slightly tilted so the blades interact with the material. When you decide the clay is dissolved tilt the mixer until almost spilling over your safety catch tub. You are not to be dumping anything out at this point.

Run water in at a speed not to exceed the capacity of your collector intake ( not the catch tub, that is for spillage ) Divert the collected outfall across a long sufficiently tilted stretch of the smallest perf plate you can find with a nugget trap [*A] at the outfall. Anything that outfalls past the trap is tailings.

Not a sluice ( a first cut classifier) but a long gutter width 'U' bent perf over an actual gutter to catch what passes. Collect that in a large tub. Large enough so any micro gold does not blow out with the over flow. This is not high flow friendly because of the particle sizes involved. Keep in mind the water flow going into that terminal collection tub is the same as what washed the material out of the mixer. So a larger volume and diameter than the mixer is necessary to avoid washout. hint: use a small mixer.

Sieve that to various sizes and then use your fav hydraulic method to process. [*B]

It takes forever to clean up clay and fresh water ( as opposed to recirc) is required ( at least for the last rinse). Faster and better to just use new water all the time. This is sampling, a larger mining operation will probably use resirc at early points unless fresh water supply is not expensive..

When the mixer is churning out clear water and the entire setup is clear water increase the speed a tad, you then have all the fines you will ever wash out. Hose down the perf.

Dump & Wash the mixer out into a collector tub and have a look at those nice clean useless gravels. If there was anything too heavy to flush out it would be there. Screen that to whatever size you figure and check. [*C]

Weigh any colors A+B+C and determine the grams per ton for that sample.

Then decide if it is worth your effort to 'mine' that stuff.

When you know what the particle size profile is you can decide how to scale up for process quantities.

With clay size materials. Surface forces are at play complicating separation.

Seek out materials which are coarser sizes, if water could have moved large material to there it could have moved gold as large as one sixth the diameter.

Keep a record of how much of the larger stuff washes out of your samples, The material left in the mixer.

 

[amSteve]

I appreciate the detailed reply. I need to explore your understanding of flour gold's behavior in fluidized clay slurry. I've taken about 2 gallons (in a five gallon bucket) of clay from the upper seam of an exposed clay bank. I've added enough water to break it down completely so I'm able to re-fluidize it at will. There is very little gravel in this --- some but probably not more than a cup's worth.

My question is, if I've fluidzed the batch, how long will it take flour gold to sink far enough that I can pour the upper part off without pouring fg out. I'm at the stage of proof of presence as opposed to recovering every single flake.

 

[KYgotGOLD]

I appreciate the detailed reply. I need to explore your understanding of flour gold's behavior in fluidized clay slurry. I've taken about 2 gallons (in a five gallon bucket) of clay from the upper seam of an exposed clay bank. I've added enough water to break it down completely so I'm able to re-fluidize it at will. There is very little gravel in this --- some but probably not more than a cup's worth.

My question is, if I've fluidzed the batch, how long will it take flour gold to sink far enough that I can pour the upper part off without pouring fg out. I'm at the stage of proof of presence as opposed to recovering every single flake.

Try an agitator in clay/water mix to speed up the process.

 

[amSteve]

Try an agitator in clay/water mix to speed up the process.

Thanks but at this point it only takes a few seconds to re-fluidize. The question is the speed at which the clay fines settle vs. the flour gold. I'm at the ready with a 100 mesh screen but i'm expecting the clay to fall thru that. (maybe i should shut up and give that a try).

 

[ConceptualizedNetherlandr]

When particle sizes get small enough density/gravity are no longer the dominant force at play. Water viscosity/kinematic viscosity and the spectacular surface area to mass ratio open up particle charge forces. Think Van der Waals. Ions. You move from classical physics to molecular physics/chemistry.

And then there is the problem of 'visible' or not. There are no easy answers.

Read up on Carlin type deposits. Basically solution gold as a contaminant in other things like pyrite which itself is in dolomite/limestone. The Carlin–type deposits represent some of the largest hydrothermal gold deposits in the world.

Some interesting work has been done with HBr chem on gold.

Check your local geology sources and figure out what the chemistry of that clay is then you can try solution and precipitation separations. But if nothing is large enough to see you need things like AA/GF to get numbers.

Now, in your case it seems you think the gold may have moved physically as particles large enough to see. If that is the case the trick is to wash it up and look at it. You will wash away all the solution gold with that cloudy clay water. Do what you can in the way of separations then throw some cheap chemicals at it, like acid followed by distilled water rinse.

I'd still seek out the largest particle materials you can find. Get a cement mixer. They come in handy for all sorts of thing. If you do a bunch of separation operations over time you accumulate nice piles of various size sands and aggregates and you already have your materials for concrete, just add cement and pour those things you always wanted

 

[amSteve]

I've screened everything down to -100 - very little didn't make it thru the 40, very little that made it thru the 40 didn't make it thru the 80 and even less that made it thru 80 didn't make it thru the 100. The -100 (roughly a gallon) is incredibly dense and now takes quite a bit of work to fluidize. I'm guessing i go straight to the miller table now.

 

[ConceptualizedNetherlandr]

I would screen that even smaller. 200 then 400. Then on each size fraction try hydraulic separation. I always wet sieve and it seems you can always get smaller material to fall out of any size that was retained. Because they stick together. Scrubbing is key.

Get a very well controlled water flow source. Neck it down to tubing size. Add some weight so it rests at the bottom of a tall container and let the water flow to fluidize the material. A pitcher with a pour spout is a good first try. tilt it so you can collect the outflow directed to the next size smaller screen. Yes, you will have fines pass that you thought had been previously screened out. Those that pass would be heavier than the larger stuff. Toss what collects in the sieve.

Keep increasing the flow, very gradually until you have reduced the contents of the pitcher to have removed most of the lighter materials. What do you see now? Clear glass is your friend.

Terminology is important. clay is very small stuff. You are dealing with mostly sands.

See these

https://archive.lib.msu.edu/tic/stnew/article/1991sep4.pdf

https://upload.wikimedia.org/wikipedia/commons/a/a0/Wentworth_scale.png

 

[arizau]

I've screened everything down to -100 - very little didn't make it thru the 40, very little that made it thru the 40 didn't make it thru the 80 and even less that made it thru 80 didn't make it thru the 100. The -100 (roughly a gallon) is incredibly dense and now takes quite a bit of work to fluidize. I'm guessing i go straight to the miller table now.

Are you dealing with concentrates or just raw, dug, washed and screen classified material?

 

[amSteve]

Check your local geology sources and figure out what the chemistry of that clay is then you can try solution and precipitation separations. But if nothing is large enough to see you need things like AA/GF to get numbers.

I've post the chem question to a very non-local, artificial source and gotten the following:

I ask:

Given the 'Quaternary alluvial deposits' nature of my property, and looking for the easiest path to verifying presence of flour gold, is the chemical composition of my clay subject to DIY chemical analysis become practical. I'm less interested in recovery than a test to verify presence.

A chem process was suggested:
he chemical precipitation test using aqua regia is a more advanced method for verifying gold presence in clay samples. Here's a detailed explanation:


IMPORTANT SAFETY WARNING: This process involves highly corrosive and dangerous chemicals that produce toxic fumes. Proper safety equipment (chemical-resistant gloves, eye protection, fume hood/well-ventilated area) is essential.


Materials needed:

• Hydrochloric acid (muriatic acid, 31-36%)
• Nitric acid (68-70%)
• Ferrous sulfate (iron(II) sulfate)
• Distilled water
• Pyrex glassware
• Heat source
• Filtering apparatus
• pH test strips

Procedure:

1. Prepare aqua regia by mixing 3 parts hydrochloric acid with 1 part nitric acid (CAUTION: mix slowly, never add water to acid)
2. Take about 100g of your 100-mesh screened clay and place in a Pyrex container
3. Add enough aqua regia to cover the sample (approximately 3:1 liquid to solid ratio)
4. Heat gently (do not boil) for 1-2 hours to dissolve any gold present
   • Gold will form gold chloride in solution
5. Allow solids to settle, then filter the liquid through filter paper
6. Dilute the filtered solution with equal parts distilled water
7. Add ferrous sulfate crystals (about 10g per 100ml of solution)
   • This causes a chemical reaction: Au³⁺ + 3Fe²⁺ → Au⁰ + 3Fe³⁺
   • Metallic gold precipitates as a brown/purple powder
8. Allow precipitation to complete (usually takes 24 hours)
9. Filter again to collect precipitate
10. Examine precipitate under magnification - gold will appear as tiny metallic brown/purple particles

The gold content can be roughly estimated by weighing the dried precipitate, though commercial assay would provide more accurate quantification.

Alternative safer approach: If you're uncomfortable with these chemicals, I'd strongly recommend either the physical separation methods or sending samples to a professional assay lab.

I've initiated contact with local assay service -- if less that a few (re: 3) hundred dollars it seems a no-brainer. Failing that price point, any thoughts re the veracity of the process that's outlined?

 

[amSteve]

Are you dealing with concentrates or just raw, dug, washed and screen classified material?

I guess i'd need to ask what 'concentrates' are if not material that's been washed and screened.

 

[arizau]

I guess i'd need to ask what 'concentrates' are if not material that's been washed and screened.

Ordinary placer concentrates consist of heavies collected from a sluice or after rough panning. Those processes eliminate the vast majority of blond sands and other worthless material/reduce the bulk volume of material that will ultimatelty be searched for gold. Black sands (usually iron minerals) and/or other naturally heavy minerals predominate the smaller sized concentrate makeup.
Good luck.

 

[amSteve]

Good luck.

I accept.

 

[Assembler]

My home sits on the edge of flood plains of the Black River not far from LaCrosse Wisconsin. Having come across some YT vids about flour gold finds in the driftless region I picked up on one of the traits that I know my property has - stratified clay beds at creek sides. I've picked up enough panning skills to have found 2 - count 'em 2 flakes of gold.

I only own about 6 acres but it has several fairly steep ravines with a number of springs of varying sizes. The springs converge to create a creek that flows something like 15 gallons per minute. One of these has cut thru a bank of clay and left exposed about 3 feet above the creek bed.

The research I've done has me understanding the potential here as follows...

• Low probability of nuggets.
• Flour gold sits at the top of the layer of clay and probably hasn't traveled very far
• Flour gold recovery by pan is not practical

I'm going to need to devise a way to probe each of the springs more systematically than i have so far and, if warranted, scale up (automate?) the recovery of flour gold.

As of this point my biggest question is the possibility that i'm not seeing smaller flakes -- one of the YTs shows a guy cleaning up using a miller table that, after collecting the visible flecks he's able to scrape the matt and produce a small pile of gold dust. Given the amount of sand i have here, that might add up to something worth something.

I'm also interested in learning about how to probe the still covered clay that sits under 20-30 feet of loom and sand. It's going to have to be an approach that doesn't include heavy machinery.

I'd be highly appreciative of any thoughts on those questions.

It sounds like the recovery rate is to low and will rule out much excavating to get to both the better clay layer and the the bed or bedrock of the creek.

Perhaps where the better clay layers are and the creek bed / bedrock is exposed a metal detector can be used to find the best layers / deposits of black sand. Try to focus on just working these layers as they get exposed by the creek or slides etc. All of the rest is costing you time, effort, money with out any measurable realistic returns.

If you can locate the better layers of black sands you could find many flakes then just the two you have found so far.
Focus on finding the flakes and the fines will be right next to the flakes.
A simple sluice box and pan can go a long ways in testing and processing.