Well, damn. There is gold in that stream after all! Thinking of a plan.

[Boarteats]

So, funny thing happened to me this weekend. Collected some magnetite from a backyard stream for my first go at smelting iron. (Just built my first forced air propane crucible furnace.) Used a magnate to pull the magnetite from the stream bed clay.

There I was Saturday grinding up a couple of handfuls of material via mortar and pestle when I look down. What do I see? About a quarter inch piece of gold flattened against the bottom of the mortar. The gold must have been encased in one of the bigger magnetite chunks. This was a bit of a shocker! I'd panned that stream several times in the past looking for gold but only came away with bits of pyrite and flakes of mica. Moreover, the damn stream is in my back yard. Go figure...

A closer look at my magnetite (after a quick dry panning) revealed a good number of small bits of gold (needed loop to see them). So question is, why did I completely miss seeing any gold in the past? Part of the answer is that I never bothered looking closely at the black sands, iron oxides, and the such. But, shouldn't I have still seen at least a little gold. Perhaps my panning skills need some work. Might the gold only be stuck in with the magnetite and no where else?

Couple things occur to me for next steps.

1. Find a reputable assay company and send off some samples to them as a sanity check. Can anyone make a recommendation?

2. Learn how to smelt gold that is mixed in with iron oxides. My first attempt yesterday didn't go very well. Lol. Ended up with a bunch of pretty black glass with little bits of iron, gold, and graphite (from my crucible, I think) all mixed together in an unholy mess. I'm reading up an Chapman flux and cuppellation (sp?) now. Should have probably done this first. Seems like a messy bit of business. Not thrilled with the idea of using lead.

Read up a little on the AR approach. Oh, hell no! As it, the wife is not thrilled with having 3000 degree blast furnace in the back yard. Adding caustic acids and other chemicals into the mix is not a good recipe for wedded bliss.

Quite an adventure so far. Any thoughts from all you seasoned, professional gold prospectors out there?

 

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[Eu_citzen]

I've read that a SMALL amount of iron can be in close contact with precious metals like platinum in nature. However, I've not seen information discussing precious metals on, covering, or alloy-ed with iron in nature. Of course, I'm new to gold prospecting. ...Anyway, the reason for the comment is that I'm starting to find pieces of malleable metal such as those in the attached pic while crushing up pieces of magnetite. Some of these suckers are strongly attracted to a neodymium magnet, so guessing lots of iron there. However, the image suggests that gold, silver, and/or copper (other) might be present as well. If so, would such an occurrence be terribly uncommon?

"Pure" iron is rare in nature, so what you're finding is likely as Arizau suggests. Top one looks like wrought iron, so.. Surely old and not natural.

 

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[Boarteats]

Yup. Makes sense for this area. Lots of bog iron. Hundred + years ago there were quite a few small time smelting ops. Thx.

....as an aside
Actually, set up a small bloom furnace a while back to better understand process old timers used to smelt iron from bog iron. Source is primarily hematite. Lots of work and really dirty. ...Smelting cast iron from magnetite in a crucible furnace is much easier and cleaner.

 

[arizau]

Here is a pretty simple but interesting experiment for you (at least it was for me) since you seem to have at least a passing interest in gold. Gold is oleophilic, sticks to oil or vice versa, so take another look at post #7.

1. Coat the bottom of an pie pan or whatever* with a smoothed thin coating of crisco.
2. Add some of your black sand fines and do some crude panning and dump and rinse off the loose material. Don't fill the pan each time just do several thin layered ones so the bottom does not get scrubbed too much. Make sure the water is not too cold so as to keep the grease sticky.
3. The grease will likely be coated or speckled with particles, some of identifiable gold if there was any in the sands to begin with.
4. There will probably be other particles (some maybe similar to that described in post #7 ?) stuck to the grease too so scrape out the mixture and either burn off the grease or dissolve it with a solvent and pan it again to separate the gold if you saw any to begin with. A little redundant here but you get the drift.
5. Put what you have left over in your mortar and grind it and pan again. Don't forget to look for gold smears in the mortar.
6. Done

With the exception of grinding, I have done this and caught and separated gold from some minus 100 mesh concentrates. I reduced about a quart of previously panned concentrate to less than a 1/8 tsp so at that point the panning was easy and the gold recovered was close to microscopic! Note: This not a usually accepted method for prospectors but the oleophilic nature of gold et al is still being used in commercial ops to produce concentrates.

Have fun if you try this.

Good luck.

*If you use a plastic gold pan then thoroughly degrease it before using again....oiled gold is subject to floating and lost while panning.

 

[Boarteats]

@Arizau, that worked great! Was able to pan down to a very small amount of heavies where the fine gold is concentrated enough that its color can be seen amongst the black sands. Best advice that I've gotten so far! Next step, build an automated mechanism for grinding the magnetite. Will take a hard look at mendoAu's rod mill suggestion.

 

[mendoAu]

Wasn't my suggestion re: rod mill but thanks anyway...HA!
Gotta figure if you use a steel pan (not to spendy and believe it or not some are made in Japan) you can skip the scrapping out thing and go directly to heating/panning. Thought I found a "find" several years ago in a garage sale...WOW, an old steel gold pan, until at home and with some cleaning up found "made in Japan" stamped on the bottom...go figure.

 

[arizau]

@Arizau, that worked great! Was able to pan down to a very small amount of heavies where the fine gold is concentrated enough that its color can be seen amongst the black sands. Best advice that I've gotten so far! Next step, build an automated mechanism for grinding the magnetite. Will take a hard look at mendoAu's rod mill suggestion.

Here is the absolute best info available about fine placer gold recovery from black sands concentrates by using a rod mill. https://open.library.ubc.ca/media/stream/pdf/24/1.0223469/4. The design and methodology starts on page 37.

 

[arizau]

Wasn't my suggestion re: rod mill but thanks anyway...HA!
Gotta figure if you use a steel pan (not to spendy and believe it or not some are made in Japan) you can skip the scrapping out thing and go directly to heating/panning. Thought I found a "find" several years ago in a garage sale...WOW, an old steel gold pan, until at home and with some cleaning up found "made in Japan" stamped on the bottom...go figure.

Yup. I did the process (except for final panning) in an old stainless steel fry pan and burned it on a bbq grill.

 

[KevinInColorado]

Here is the absolute best info available about fine placer gold recovery from black sands concentrates by using a rod mill. https://open.library.ubc.ca/media/stream/pdf/24/1.0223469/4. The design and methodology starts on page 37.

This Clarkson paper is what inspired me to build a bench top rod Mill a couple years ago. Works great. There’s a thread about my experiments on Tnet somewhere

 

[Boarteats]

Just wanted to share this pic given the help/advice that you all have provided. Used some acid to remove the iron oxides from the first piece of gold that I stumbled across while grinding up magnetite with mortar and pestle. Does this count as a nugget?

 

[mytimetoshine]

Just wanted to share this pic given the help/advice that you all have provided. Used some acid to remove the iron oxides from the first piece of gold that I stumbled across while grinding up magnetite with mortar and pestle. Does this count as a nugget?

Nice!!!

 

[arizau]

Looks to be a little on the plus or minus side of a gram. Nugget and rarely shaped compared to what I have seen. That thing has some kin somewhere close so go find them..