# Placer Rhodium



## kjavanb123 (Dec 21, 2021)

Hi everyone 

I was sampling the dried river bed in Aan ophiolite zone that some chromite ore mining had taken place. 

I sieved the sample into minus 1mm mesh and plus 60 mesh. 

Using Deano AR test for ore, I dissolved the finer part in simmering AR and after brown fumes were gone, filtered and collected brown solution. 

A drop of that solution reacted with stannous chloride testing solution and first turned to brown then pale purple. 

Added sulfamic acid at room temperature to remove any excess nitric.

I did the stannous test again on solution and no color change. 

Prepared a DMG solution, and added to the main AR solution and got this canary yellow perticpitant.



I filtered and zinc cemented the yellow powder which after washing turned to almost white color. I added zinc powder but the mix color changed to brown instead of the usual gray color. 

Added hcl to mix above and got small black powder left. 

I am testing further to find out if that black to gray powder is Rhodium, or Platinum. 

I was looking for PGM flakes since the up the river is massive Perioditite and Dunie and lots of Serpantine. 

Thanks


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## Lino1406 (Dec 21, 2021)

No white compound of PGM is knowm


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## kjavanb123 (Dec 21, 2021)

Lino1406 said:


> No white compound of PGM is knowm


Hi Lino

Thanks for the reply. The first drop resembles Pd drop as the canary yellow.


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## orvi (Dec 21, 2021)

kjavanb123 said:


> Hi everyone
> 
> I was sampling the dried river bed in Aan ophiolite zone that some chromite ore mining had taken place.
> 
> ...


Aside palladium, also nickel (II) and platinum (II) can form insoluble DMG complexes. Other metals also complex with DMG, but the complexes formed are readily soluble. 
Drop on the photo look like typical Pd(DMG)2 to me.

Now i am confused with that what you say. You precipitated assuming Pd (and maybe something else) from AR liquid, filtered the yellow precipitate and cemented remaining mother liquor with zinc to get white residue ?

If you can, maybe try to heat a bit of the obtained powder with concentrated sulfuric acid. If rhodium is present, you will see typical pink-red colour of Rh


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## kjavanb123 (Dec 21, 2021)

orvi said:


> Aside palladium, also nickel (II) and platinum (II) can form insoluble DMG complexes. Other metals also complex with DMG, but the complexes formed are readily soluble.
> Drop on the photo look like typical Pd(DMG)2 to me.
> 
> Now i am confused with that what you say. You precipitated assuming Pd (and maybe something else) from AR liquid, filtered the yellow precipitate and cemented remaining mother liquor with zinc to get white residue ?
> ...


Hi orvi

Thanks for your reply. That yellow drop was when I added DMG to main AR solution. 

Once I filtered the yellow powder and washed it with water it became pale yellow almost close to white. 

I added zinc powder to that and got the following mix. 



This was dark gray when it was yellow Pd DMG salt. However the foam on the edge had a pink color to it. 

I added hcl to the above and small amount of black powder remained which I filtered and washed. Then to test that black powder I added nitric acid, which dissolved it but no color change on solution or stannous chloride testing solution..

As for Ni(I) drop, I thought it would be red and solution must be alkaline for DMG to work. 

I completed another batch of coarse Placer part which I post with stannous result which shows very positive for gold. 

I will remove all the black magnetic fine from the Placer and smelt with silver. 

Thanks


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## orvi (Dec 22, 2021)

kjavanb123 said:


> Hi orvi
> 
> Thanks for your reply. That yellow drop was when I added DMG to main AR solution.
> 
> ...


DMG alone is close to white or off-white powder, which is poorly soluble in water. I am just guessing that you adsorbed some ions from solution to the surface of DMG, and when washing, you washed the thing away from it. This could explain the negative stannous afterwards.

Yes, nickel is very, very sensitive with DMG. But above pH 5


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## kjavanb123 (Dec 24, 2021)

orvi said:


> DMG alone is close to white or off-white powder, which is poorly soluble in water. I am just guessing that you adsorbed some ions from solution to the surface of DMG, and when washing, you washed the thing away from it. This could explain the negative stannous afterwards.
> 
> Yes, nickel is very, very sensitive with DMG. But above pH 5


Thanks for reply. I am preparing a new batch and will post the process from A to Z here with pictures.


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## kjavanb123 (Jan 2, 2022)

Hi

This is an update on PGM placer assay. 

I prepared concentrates from a dried river bead that came from mountains with few chromite mines and host rocks are Serpentine, dunite and perioditite. 

Using my homemade blue bowl, I was able to concentrate around 98grams and selected 18g of that and placed on top of the cupel. 

Then added 10.13g silver powder on top of above. 

Finally, I placed about 240g of lead sheet to cover the concentrate and silver and let it stay in my furnace. 

Here is a photo of it at the beginning of the cupel. 




After cupel was complete, I got 8.81g of silver bead which I dissolved in nitric acid. As it can be seen in picture below the nitrate solution turned orange color which indicates Pt or Pd in solution. 



I added hcl to drop silver as chloride, but solution is indeed the orange color when Pt or Pd are dissolved in nitric acid. I forgot to check with stannous at this point. 



I washed the silver chloride with hot water and rinsed to another beaker but when I checked the orange solution it was negative for Pt or Pd. 

I didn't have a test solution to confirm my stannous solution, so I went ahead and used zinc powder to drop any Pt or Pd. 

Got this black powder which I added AR and is sitting on heat to see if this was indeed PGM. 



I still have another 80g of cons to smelt. I will keep you guys posted. 

Thanks
Kj


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## kjavanb123 (Jan 13, 2022)

Hi

I ran a sample from river bed in AR and got this color, what is on the left is to check the stannous chloride solution from a very concentrated gold solution, does that spot on the right of the q tip means Palladium? 




Thanks and best regards
Kj


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## kjavanb123 (Jan 16, 2022)

Updates

Hi everyone, my hcl leaching the minus mesh 60 size of river bed sample failed due to a crack in the beaker.

So I processed the plus mesh 60 and minus 1mm size in hcl, then ran the undissolved in my homemade blue bowl, and concentrated it. 

The concs weighed 46g, I added 46g lead oxide, 90g of Flux (soda ash, borax, silica) and 10g of flour. 

After smelting completed and I poured the melt into cone mold, I was left with 19g lead button. 



I have used the lead oxide sinked into a cement cupel. So it wasn't a pure lab grade lead oxide hence the much lower lead bead. 

I cupeled the lead bead and got 2 separate beads, one silvery color and the other one black color as can be seen in the following pictures. 





I put 2 beads in nitric acid and heat it, the color of solution changed to light brown then clear and I was left with mix of powders. 

I added AR to the powder at room temperature and that dissolved the gold powder. 

I filtered the gold solution and washed the powder into another beaker and tried to heat it in AR as can be seen in the following picture, AR didn't effect the powder. 



I checked the solution with stannous chloride and it was negative for gold or Pt. 

I washed and dried the blackish powder and It weight exactly 0.003 Oz as it did after cupeling. 

The only PGMs that not soluble in AR are Iridium and Osmium. 

The powder was pretty heavy after I added water and tilted the beaker it slowly moved. 


Thanks and best regards 
Kj


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## cosmetal (Jan 16, 2022)

Can you get an ICP-MS assay done on the original sieved placer sample?

Peace and health,
James


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## orvi (Jan 16, 2022)

Difficult to say from these observations. Ruthenium and also rhodium are quite resistant to AR, but finely divided powders like you should obtain from nitric leaching should be attacked to some extent after some boiling (mainly Rh).
Also note that AR solution alone on heating can turn yellowish-orange/brown, and as the NOCl and chlorine boil out, it clear up quite a bit.

Best thing would be to run ICP or XRF analysis to get some clue as was suggested by cosmetal. This could save you quite a bit of time and frustration with home-testing and receiving unconclusive results.


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## kjavanb123 (Jan 16, 2022)

Thanks guys. I will look at the ICP testing.


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## kjavanb123 (Jan 18, 2022)

Hi all

I decided to cupel both powders from processing the last placer. 

But I keep finding placer gold in pretty much any river bed around town. Host rock is Serpantine or Dolomites. 

I just picked a kg of sample from this dried bed which is few feet from a dam just an inch of the surface. 







I used a sieve to separate them into minus 60 mesh and plus 60 and minus 1mm.

I used equal part lead oxide as the dried concentrate, and 4 parts of Flux plus 2 parts flour to get melt more fluid. After that I smelted the charge and cupeled the lead bead to get 2 pieces of silvery buttons as seen in the following pictures.


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## kjavanb123 (Jan 18, 2022)

Here is the picture of 2 small beads resulted from cupeling. They weigh 0.001 Oz or 0.02g.



After dissolving them in boiling nitric acid, got the usual brown gold powder as seen below. 



This is from few grams of dried concentrates came from a kg of gravel of the surface in a dried river bed, far from the mountains that are mostly Serpantine and shales. 

Is this a good sign to proceed and maybe dig deeper to get more volume and see what the yield is? 

Thanks and regards
Kj


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## orvi (Jan 18, 2022)

kjavanb123 said:


> Here is the picture of 2 small beads resulted from cupeling. They weigh 0.001 Oz or 0.02g.
> View attachment 47904
> 
> 
> ...


As hobby golddigger, definitely yes. Go deeper.
Just inch from the surface is nothing for gold. If gold is present in particulate form, bigger flakes will sink to the bottom of the riverbed, eventually they hit bedrock. But generally deeper you get, more gold you find. It is more complicated than this, but for most instances it works. When gold is very fine (flour gold), it has tendency to collect in high-friction zones and floodplains, quite commonly in the just top few inches of gravel - opposite to classic bigger chunks/flakes.
If you can get 20mg of values from 1kg of sand, man.. that is incredibly rich gravel  certainly prove it with more testing. Is the gold visible ? Or entrapped somwhere in the cons only ? Certainly try to explore it further, it could have big potential.

Try to harvest more concentrates from panning (assuming you pan the material down to cons), say 100g or so, and roast them. Then try to crush them fine and try to pan them again.
Sometimes, gold could be liberated just with this technique, if it is enough big to separate by panning. It is a quick setting and you will see results immediately.

Also if assaying that low concentrations of values, make double sure that your lead oxide or lead used do not contain any traces of silver/gold. This could terribly skew the results of analyses. Also I see you using cement cupel - this could crack miserably, making you loose some beads=not collecting them to one puddle and bead. I will advise to crush whole top of the cupel and pan out tiny beads left/entrapped.


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## kjavanb123 (Jan 18, 2022)

Thanks Orvi

I am actually very new to prospecting, I was looking for PGMs in riverbeds but ended up with gold pretty much everywhere I looked. 

Good points on the purity of lead oxide, what I usually do I cupel the Lead I buy to remove any traces of PMs which is only silver, then crush the lead oxide and use it in smelting. 

My lead for sure doesn't have any gold or PGMs, only very small amount of silver which mostly removed by that treatment. 

I also use my homemade blue bowl to get the concentrate, I always dissolve the tailing in AR to make sure I didn't lose any values. 

Gold flakes are not seen as particles in the blue bowl so must be trapped by the minerals, which smelting I suppose pick it up. 

I make sure to cupel the black powder from my last smelt to see if it is any PGMs. And dig deeper to collect more gravel say 10kg then measure the fine and coarse and weigh the concentrate prior to smelting to have a better yield info. 

Keep you guys posted 

Kj


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## orvi (Jan 18, 2022)

It is quite simple in terms of general rules how to find heavies in the river or stream, but applying these correctly for specific case/stream/river is sometimes very very challenging.

If it is a* small stream with relatively steep descending angle (go downhill) and the bedrock not very deep* (like 1,5-2 meters maximum depth), *material tend to be separated evenly* from top to bottom layer in means of heaviness. So most gold/heavies at the bottom, less on the top. This only apply assuming that in flood, *whole profile of creekbed moves in some way.*

When stream hit more planar surface and widen the valley, create meanders and *water speed slow down, layering of gold inside the sediment profile often changes drastically.* Here, biggest of the biggest floods that could happen cannot move the whole layer of sediments (often several meters high) evenly. Just to some depth - and this is very important. 
In these conditions, *larger stream or river tend to form layers of sediment*, often differentiable with various color of the sediment, different fractions of rocks (more big boulders/more sandy/just sand and boulders/mix) and* most importantly false clay bottom layers*. When digging on big streams or rivers, focus on these.
Gold and heavies will penetrate just to the bottom of this false-bedrock layer. Movement of the water cannot penetrate deeper in these conditions. Eventually after years and years it will break it and erode the sediments deeper, of course.
*On larger streams and rivers, you can very often find rich layer just on the top of the sediment,* to the minimal depth. Usually less than 25-40cm, and heavies and gold start to vanish. Big sand deposits on big rivers like Danube tend to make the richest layer directly on the top - digging just 15cm deep and all gold is practically gone. Eventually if you dig the whole layer to another false bottom quite more deeply, you will often eventually find another similar enriched layer.

For sure geology here (central Europe) and in your homeland could be totally different. But I could share my experiences in the field.

Firstly, bigger fractions usually do not contain much values. As the mountainside erode and pieces fall, tumble, crack etc. while going downhill and meeting the river or stream, most of the values from veins usually liberate from gangue rock. Vein structures usually containing sulfides/ore type minerals, which are softer than (here) mainly quartz veins and veinlets. Because of this, the vein structures easily crack around these grains/small veins and then liberate the values from bigger pieces of rock. For sure some values are trapped deep inside big rocks, but they are difficult to access and are very scarce most of the times.
I recommend to take as we use to say "wheelbarrow sample"  sift it to say 3 main fractions (15mm/5mm/>5mm) and pan these separately. You get some kind of concentrate from every one of these. Observe the heavy minerals - usually darker/black in colour as bulk. If you do not observe the distinct heavy fraction in above 5mm fraction, you can do a control smelt of the last remains in your pan - but generally said no heavies=no values in most cases, so you can skip this fraction entirely.
Most of the times the gold/silver is mainly entrapped in fine fractions (>1,5 mm) here where I live. Mainly in sulfide minerals like pyrite and arsenopyrite. But this depends largely on geology.
If there is good portion of magnetic material, you can do a test leach on it, but if it does not contain values, it will be very easy to remove it with magnetic separator or basic magnet at small scale.


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## kjavanb123 (Jan 18, 2022)

Thanks Orvi for your detailed info. I will apply them to my near future venture and get back to you all.


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## kjavanb123 (Feb 15, 2022)

Hi all

Here is an update on my gold placer. This sample was taken from few inches from the surface of a river bed that came from granite and quartz mountains. 

I sifted the sample into minus 60 mesh and plus 60 mesh. 

Fine part weighs around 96g. Here is the stannous chloride test with AR solution of this part. 



Very strong purple and AR solution volume was 400ml.

Next step I will dig more from. The same spot to be 10kg, use blue bowl to concentrate and smelt to see how much gold I get.


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