Some BC Black Sand Under the Microscope

[Heavy-Black-Sand]

A few picts of some BC black sand concentrates under the microscope ..... a couple things about these concentrates .....

* the bulk of the high purity gravity gold has already been removed via fine gold sluicing .....

* the metallics in these picts are what the fine Gold sluices have a difficult time capturing .....

* this black sand comes from Placer claims located on ground where larger scale Placer mining occurred in the 1800's, including both hydraulicing & dredging ships

* picts are aprox. 150x to 200x magnification

* assays of the heaviest black sand that comes out of the sluices box concentrate tails (after the vast vast majority of visible gold is removed) runs around 10 oz. AU per ton, with some Silver ..... assays also pick up some PGM values here and there

 

[cosmetal]

Very nice pictures - thanks! Are you using a gemological (aka gemmological in Canada and Great Britain) microscope to take the pics?

A lot of Ag showing or is that Pt? How much Ag and Pt shows on your assay?

Curious looking red stone in pict10. Any idea what it is?

Peace and health.
James

 

[4metals]

picts are aprox. 150x to 200x magnification

Were these pictures taken with an attachment for a smartphone? If so, what was it, I like the results!

 

[Heavy-Black-Sand]

Very nice pictures - thanks! Are you using a gemological (aka gemmological in Canada and Great Britain) microscope to take the pics?

A lot of Ag showing or is that Pt? How much Ag and Pt shows on your assay?

Curious looking red stone in pict10. Any idea what it is?

Peace and health.
James

* Microscope is a Optex USB Digital Magnifier ... it plugs into the computer via USB cable


* Early stage testing on the Silver/Grey pieces point towards combos containing various mixtures of AG/AU/PT/PD ... plus with what i suspect will be some type of a base metal component ... originally, I didn't know the Silver/Grey pieces were in the black sand, so most of my assay work has been Gold oriented ..... also, the Silver/Grey pieces are very difficult to gravity separate from the black sand, as they are a little lighter than the high purity AU pieces, and they are para-magnetic, so they tend to stick to the black sand tighter than the gold ... and becuase they are more of a silver/grey color, and usually 30 mesh and smaller, they don't tend to visually stick out easily like the bright high purity Yellow Gold pieces, so they tend to go by most people without notice ..... which may partially explain the lack of documentation at the BC Ministry of Mines regarding PGM's in this particular drainage ... however, there is some documentation regarding PGM occurrence in this drainage at BCMoM - but it is sparse.

But now that I'm now approaching an advanced level of gravity separation for microscopic black sand components, i'll be able to concentrate more purified batches of this Silver/Grey material for more detailed analysis ... i'm thinking about taking in a batch for an XRF analysis soon ..... but right now, i'm more focusing on piecing together the items to start doing smelts on the heaviest metals/black sands that come out of alluvial gravels for the gold content.

* Red piece is likely Garnet

 

[Heavy-Black-Sand]

Were these pictures taken with an attachment for a smartphone? If so, what was it, I like the results!

I'm using an Optex USB Digital Magnifier ... it plugs into the computer via USB cable ... it's this model here that can be seen in this kijji listing .....

https://www.kijiji.ca/v-ipad-tablet-accessories/red-deer/optex-200x-digital-magnifier-nib/1577529116

 

[Heavy-Black-Sand]

Were these pictures taken with an attachment for a smartphone? If so, what was it, I like the results!

This is what a close up of the super concentrated black sand looks like with a 3 year old Smart-Phone .... i suspect you can get apps for your smart phone to get better microscopic picts ....

 

[4metals]

The photos magnified 150-200x compared to the smartphone shots are night and day. Some of the photo’s that members post of rocks would look a lot different at 150-200x, still not as definitive as an assay but potentially eliminating some of the guesswork.

You actually did it right, both excellent photo’s and an assay.

Thanks for the info on the camera.

 

[Alondro]

* Microscope is a Optex USB Digital Magnifier ... it plugs into the computer via USB cable


* Early stage testing on the Silver/Grey pieces point towards combos containing various mixtures of AG/AU/PT/PD ... plus with what i suspect will be some type of a base metal component ... originally, I didn't know the Silver/Grey pieces were in the black sand, so most of my assay work has been Gold oriented ..... also, the Silver/Grey pieces are very difficult to gravity separate from the black sand, as they are a little lighter than the high purity AU pieces, and they are para-magnetic, so they tend to stick to the black sand tighter than the gold ... and becuase they are more of a silver/grey color, and usually 30 mesh and smaller, they don't tend to visually stick out easily like the bright high purity Yellow Gold pieces, so they tend to go by most people without notice ..... which may partially explain the lack of documentation at the BC Ministry of Mines regarding PGM's in this particular drainage ... however, there is some documentation regarding PGM occurrence in this drainage at BCMoM - but it is sparse.

But now that I'm now approaching an advanced level of gravity separation for microscopic black sand components, i'll be able to concentrate more purified batches of this Silver/Grey material for more detailed analysis ... i'm thinking about taking in a batch for an XRF analysis soon ..... but right now, i'm more focusing on piecing together the items to start doing smelts on the heaviest metals/black sands that come out of alluvial gravels for the gold content.

* Red piece is likely Garnet

I have a lot of this silvery material in my black sands recovered from a glacial moraine in NJ, material which originated 10k-25k years ago from Eastern Canada. It does tend to be about the same density as the gold flakes, very hard to wash away from them despite being very fine dust.

It'll take until my furnace is completed next year to do a smelt, but I have about 10 lbs of these sands saved up. Also, with my magnifying glass, I happened to find a few cracked open hematite grains with a tiny speck of shiny gold inside.

 

[Heavy-Black-Sand]

I have a lot of this silvery material in my black sands recovered from a glacial moraine in NJ, material which originated 10k-25k years ago from Eastern Canada. It does tend to be about the same density as the gold flakes, very hard to wash away from them despite being very fine dust.

It'll take until my furnace is completed next year to do a smelt, but I have about 10 lbs of these sands saved up. Also, with my magnifying glass, I happened to find a few cracked open hematite grains with a tiny speck of shiny gold insSome big Nickel deposits in Ontario

There are some large Nickel deposits in Ontario ... Nickel deposits are "sometimes" found with PGM occurances ..... so, if you've got a base metals like nickel or iron as an impuritiy in your individual PGM particles, it's going to drop the specific gravity of those particles - making them more difficult to gravity concetrate in Gold gravity recovery equipment ... as the micron Gold gravity recovery equipment appear to be primarily tuned to perform best around the 19 specific gravity threshold, at least thats been my observations so far.

 

[goldshark]

I don't know what quantities you are looking to process, but a ball mill or cement mixer with Mercury, may be the process of choice. Retorting, properly sealed and operated, would most likely remove more Mercury from the environment, slowly increasing your supply. If you are under close government scrutiny, you may need to retort the black sands, after your amalgam has been separated from it.

 

[Heavy-Black-Sand]

I don't know what quantities you are looking to process, but a ball mill or cement mixer with Mercury, may be the process of choice. Retorting, properly sealed and operated, would most likely remove more Mercury from the environment, slowly increasing your supply. If you are under close government scrutiny, you may need to retort the black sands, after your amalgam has been separated from it.

I have been able to obtain a jar of Mercury ... and did do some testing on the fine/micron Gold ... what i found is the Mercury didn't do as good of a job of amalgamating the fines as i thought it would ... after doing some research, it appears mercury can struggle a bit when confronted with fines that come fresh out of alluvial gravels due to various contaminants that can cover/coat fine gold ... it was suggested for mercury to perform at very high levels, the Gold should be chemically cleaned prior to amalgamation ..... i suspect the addition of copper plates would aid Mercurys amalgamation performance, however, due to the difficulty in obtaining the Mercury, the test results, and research, i decided to not pursue Mercury as an option.

The concentrating process i've currently evolved to is; fine gold sluicing, followed by a run thru an i-con centrifuge ..... the fine gold sluice does a pretty good job of capturing fines down to aprox. 100 to 200 mesh ... while the i-con pulls out fines into the 400/500 mesh range ... the added benefit of the i-con is speed - it can take a much higher feed rate than the fine gold recovery sluices.

 

[goldshark]

You need to add a little Sodium Hydroxide to the mix, while tumbling. Pyrites can "sour", or coat the Mercury, with a scum which hinders it's ability to amalgamate. SH will eliminate the "scum". Attrition in the mill will remove surface coatings, which hinder binding, also exposing Au inside the various locked up mineral varieties. Sounds like you are getting a good final product of clean Au, but you should be getting better than 1% Au in the final concentrate, if I am understanding you correctly.

 

[Heavy-Black-Sand]

You need to add a little Sodium Hydroxide to the mix, while tumbling. Pyrites can "sour", or coat the Mercury, with a scum which hinders it's ability to amalgamate. SH will eliminate the "scum". Attrition in the mill will remove surface coatings, which hinder binding, also exposing Au inside the various locked up mineral varieties. Sounds like you are getting a good final product of clean Au, but you should be getting better than 1% Au in the final concentrate, if I am understanding you correctly.

I've basically made the decision to avoid the mercury method ... to many potential risks ... but thanks for the insights on it though.

The aprox. 1.5% visible gold content in black sand concentrate referred to previuosly was obtained by washing gravel thru jigs, then concentrating jig concentrate thru a "Knudsen bowl" (not an iCon) after running many many hundreds of tons of in-situ gravel.

For small tests and hand mining runs, i've got a couple fine gold recovery sluices that perform exceptionally well ... they just lack speed.

I'm currently targeting roughly aprox. 3% to 10% visible gold content in the black sand concentrate for future smelt testing, depending on individual circumstances ... future testing will help unfold what's the best route.

 

[macfixer01]

At least the magnification quoted for that Optex microscope looks believable. So many brands really pump up the numbers to sound more impressive. They’ll use an identical looking scope and factor in larger screens and digital zoom, then claim 600X, 1200X, or 1600X. Optically they’re not any better, and just sacrifice clarity for a larger image.

 

[Alondro]

There are some large Nickel deposits in Ontario ... Nickel deposits are "sometimes" found with PGM occurances ..... so, if you've got a base metals like nickel or iron as an impuritiy in your individual PGM particles, it's going to drop the specific gravity of those particles - making them more difficult to gravity concetrate in Gold gravity recovery equipment ... as the micron Gold gravity recovery equipment appear to be primarily tuned to perform best around the 19 specific gravity threshold, at least thats been my observations so far.

We shall see what comes out when it's all smelted. What's nice is that these sands have been ground up and oxidized for at least 10,000 years. No sulfides should be left in them at all! Should be an easy smelt.

 

[Heavy-Black-Sand]

We shall see what comes out when it's all smelted. What's nice is that these sands have been ground up and oxidized for at least 10,000 years. No sulfides should be left in them at all! Should be an easy smelt.

A couple different Placer smetling experts in BC do roast them for aprox. 20 to 30 mins around the 1,100 F range before the smetling process (just to be thorough) ..... and they have a very high degree of success with their smelts ..... but i think your generally right - minimal sulphides.

 

[goldshark]

Around here, we see a considerable amount of Sulfides in our black sands. Unoxidized rock is constantly being ground up, releasing new minerals all the time. Distance traveled in the glaciers is up to 15 miles.
1,100 F can cook a rind around a Sulphide particle, kind of like searing a steak. This rind seems to keep the inner particles from completely oxidizing. Recommended temperature is not to exceed 750 F.

 

[goldshark]

A couple different Placer smetling experts in BC do roast them for aprox. 20 to 30 mins around the 1,100 F range before the smetling process (just to be thorough) ..... and they have a very high degree of success with their smelts ..... but i think your generally right - minimal sulphides.

I would still put some iron nails, or nitrate into the flux during your smelt. It won't hurt a thing.

 

[Aled]

A couple different Placer smetling experts in BC do roast them for aprox. 20 to 30 mins around the 1,100 F range before the smetling process (just to be thorough) ..... and they have a very high degree of success with their smelts ..... but i think your generally right - minimal sulphides.

Greetings Heavy Black sands. I do enjoy the fine pictures you posted. Question what type of Flux make up would you recommend for your Black sand smelting gold recovery process. Kindest Regards Avled.

 

[Heavy-Black-Sand]

Greetings Heavy Black sands. I do enjoy the fine pictures you posted. Question what type of Flux make up would you recommend for your Black sand smelting gold recovery process. Kindest Regards Avled.

Just to be clear ... the hands on smelting on my black sands to date have been done by other people - i've only just been an observer so far ..... i'm still aprox. 3 or 4 weeks away from attempting my own smelt ..... the flux recipe i'm working with right now contains a mixture of following, with the aprox. proportions of each, yet to be fine tuned .....

* Black sand concentrate ..... 30 grams

* Na2CO3 (Sodium carbonate) ..... 50 to 60 grams

* PBO (Litharge) ..... 80 to 120 grams

* SiO2 (Silicon dioxide) ..... 24 to 40 grams

* Na2B4O7 (Borax) ..... 14 to 16 grams

* CaF2 (Calcium fluoride) ..... 2 to 10 grams

* Flour ..... 5 to 8 grams

The amount of black sand in the ingredients (30 grams is the constant) ..... the range shown in the other ingredients are variable, and will need to be fine tuned, as Black Sand varies from location to location, so the final recipe has to be dialed in thru testing.

Also .... this may not be the final recipe .... there may be some additional tweeks/additions/subtractions here and there.