# Iron(II)-chloride for precipitation



## Alkymida (Oct 5, 2012)

Hi all

I´ve used Iron(II)chloride for precipitation of gold many years ago with good result and wonder why i can´t find anything about that?
To me it was very easy to make and work with and it precipitated instantly after evaporation and dilution of goldchloride with water.

Best regards
Peter


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## ericrm (Oct 5, 2012)

that is very interesting ,please tell us more


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## Alkymida (Oct 5, 2012)

Hi Eric

When all metal is dissolved in AR (3:HCl, 1:HNO3) and you have evaporated excess acids by heating whithout boiling you end up with a syrup-like substance which is taken off the heat to cool. 
You now have ruby-red crystal-mass of AuCl3/AuHCl4.
Then you dilute in water to a citrus-yellow liquid.
While evaporating you can prepare a fresh portion of Iron(II)-Chloride by dropping some iron in konc. HCl. I used some small nails in excess and got a saturated blue liquid.
I then added this to the goldsolution drop by drop with a pipette. When a drop hit the liquid it instantly made a dark/black "cloud" in the liquid which quickly sank to the bottom of the beaker. I kept adding drops till no more dark turned up.
Then i filtered, rinsed and dried the gold.
After that i sintered the powder to form metal. :0)
I think it was very easy to work with and funny to see the gold form in that way.

The procedure i read in a chemistrybook from 1972 (i got for Christmas that year):
Paul Bergsøe: "Kemi på en anden måde" (Til selvstudie af uorganisk kemi) ~ "Chemistry in Another Way" (A tutorial in inorganic chemistry)

EDIT: Spellings and i might add it was 32% HCl and 67% HNO3.

Peter


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## maynman1751 (Oct 5, 2012)

I have made and used ferrous sulphate to precipitate but never the chloride. How long does it take to prepare this solution? Interesting, Thanks!


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## Alkymida (Oct 5, 2012)

Hi maynman

The iron nails dissolves quickly - a little slower than zink.
You don´t need much.

If you take the nails out the Iron(II)chloride will turn into Iron(III)chloride. Yellow stuff for dissolving copper on PCB-boards.

EDIT: PBC-boards to PCB-boards

Peter


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## hfywc (Oct 6, 2012)

very interesting but wouldn't this contaminate the gold you are trying to refine?i would say this is useful for initial recovery or in cases where there are no other precipitant available.


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## Geo (Oct 7, 2012)

ferric chloride would indeed contaminate the gold. its best to keep other metals out of your solution if you can. 

if it was feasible or a viable alternative, one of our more learned members would have suggested such a simple and common precipitant a long time ago.


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## Alkymida (Oct 7, 2012)

Hi again

I thought about that too. But on the other hand you only use what is needed to precipitate.
It was because that was the one i learned to use years ago i asked why it wasn´t mentioned.

Best regards
Peter


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## ericrm (Oct 7, 2012)

what happen to the ferrous chloride after it has drop the gold ? what does it become?


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## Geo (Oct 7, 2012)

Peter, that is what this forum is all about. learning a better way. there are many compounds that will precipitate gold from solution, but just because they drop gold from solution doesnt mean its better than the next. as a matter of fact, there are many that are far worse to use than others because they will contaminate your refined PM's. here on the forum, we try to weed out misinformation. any new member reading this thread may be thinking "if this guy says this will work and its cheaper and easier to get than what everyone else says to use, im going to try it". the next thing you know, we will have a rash of questions of people wanting to know "why is there iron in my gold?" and "i followed directions from the forum and i still cant get my gold pure".

im not busting your chops about this and i understand your just wondering why you were taught to use it a long time ago and no one here seems to know anything about it. i promise you, if it drops gold, a large percentage of members here know about it but would rather do it the right way.


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## Barren Realms 007 (Oct 7, 2012)

It will also drop your copper and other contaminants during the precipitation and leave you with a dirtier gold to deal with.


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## Alkymida (Oct 8, 2012)

Hi again

Eric: It will turn fron Iron(II)chloride to Iron(III)chloride.

Geo: I see what you mean. Maybe it was because the textbook only was dealing with how to dissolve and recover gold, not when other impurities are mixed in.

Barren Realms 007: Yes and no. If i just put a lot in it will as you say precipitate the other metals. If i use it dropwise i will stop as soon as the precipitate doesn´t fall very quickly to the bottom. It´s in a very diluted liquid it´s done.

Best regards
Peter


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## hfywc (Oct 8, 2012)

peter,

thanks for sharing your little secret!

regards,
alan


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## Geo (Oct 8, 2012)

Peter, if you dont mind me asking. how long did it take you to get to where you knew when to quit adding the iron chloride? i guess what im saying is, did it work as expected the first time you did it without any issues. and second, did you have any problems with contamination of the final product or did you check for quality?


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## qst42know (Oct 8, 2012)

Ferrous sulfate is known to be selective and easy to make. I'm not enough of a chemist to stray from the known paths. :mrgreen:


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## bmgold2 (Dec 23, 2013)

I've been looking for this information for a while. What I have been doing is trying to get The Gold Hunter's Test Kit that I purchased recently to leach gold from some bought gold ore that I got from Action Mining that is supposed to have at least one ounce of gold per ton in it. I have been trying lots of things to get it to show a positive test for gold and have had no luck at all. I do get and orange test from the stannous chloride (or whatever their test chemical is) and am pretty sure that is indicating iron.

If there is iron in the ore, will that keep the gold from going into the solution or precipitate it back out if it does leach?

bmgold2 - former bmgold but couldn't get my old password changed and can't remember it


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## butcher (Dec 23, 2013)

I would not waste my money on the The Gold Hunter's Test Kit, My daughters bought me one for my birthday years ago, it did not work, I suspect the chemicals they use have a shelf life, and if you do not get a fresh kit it will be useless, I could not determine what the kit was for sure, its been so long ago, but I suspected it some type of thiosulfate or iodine leach, the chemicals of the leach I believe because of the dangers involved they chose fairly safe chemicals for their product, as shipping of more dangerous chemicals would become prohibitive, whatever the kit contains it is surely nothing that you could not make on your own with a few chemicals and a little know how.

Iron will leach form ore before gold will with most of the chemical leaches we use, iron in solution can look very much like copper (green) or gold (yellow) when dissolved into a solution.
other base metals will also leach from an ore of group of metals before the more noble metals will, so unless the leach is selective for a certain metal, we can expect the more reactive metals to dissolve out of solution first.

Try this test on your ore:
Powder the ore, a pinch of the ore, in a surplus mix of one part ammonium chloride, and 21/2 parts ammonium nitrate powders, mix well fuse these together with heat to a molten syrupy molten salt, cool some and add a few drops of HCl to dissolve the salts in solution, dip a Q-tip into this solution and test with fresh stannous chloride. this test can be done in the field with some simple tools in a kit, basically the NH4Cl and NH4NO3 salts in a molten fused state with the gold in the ore act similar to aqua regia, the fused gold chloride salt dissolved in aqua regia, can be tested with stannous chloride, a very sensitive test for gold ions.

With some ore it is better to flux out the base metals, and use a collector metal in the flux, then a cupel, and or use acids to see what you may have.

One ounce a ton? that sounds like a fairy tale. How much did they charge you for it, I know that store does not give anything away cheap, but nobody sells gold cheap or gives it away. Have you tried crushing roasting and panning the ore? with that much gold I would expect to see gold in the pan.


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## bmgold2 (Dec 24, 2013)

The Gold Hunter's Test Kit is a saturated salt and nitric acid leach according to their website. The indicator solution is NOT stannous chloride according to what I have read somewhere online. It is supposed to last longer than stannous chloride.

I am now thinking that something in their indicator solution is reacting with the iron and causing an orange color to the spot test. I added some known good gold containing solution to a small sample test of black sand which was giving me the orange color test. With the kit's indicator, I got the orange spot with a purple spider web around the outside of the spot (on paper towel). Then I tried a homemade stannous chloride test and ONLY got the purple spot.

At least that tells me that the iron containing solution didn't precipitate the gold. It might keep it from being dissolved in the first place (I didn't test it again yet).

As far as the Action Mining ore, it says it is guaranteed to contain at least one ounce of gold per ton. If I'm calculating right, $1200 oz divided by 2000 pounds equals 60 cents per pound. It cost me $7 plus shipping (over $10) for that pound of ore. It was sold as test ore for their assaying kits so I expect it really does contain that much gold.

I did try panning some and found no indication of free gold. I roasted some and panned it and still no visible gold. I'm pretty sure the kit would work if there was free gold in the sample (if your pinch of ore contained the free gold). Actually, if it contained free milling gold, crushing and careful panning would tell me if there was gold in it and the kit wouldn't really be needed. It is more a yes/no test and not really an assay to tell how much gold is in the ore. The color should give you an indication of how much gold by the darkness of the purple spot but not really a substitute for an assay. Might save you from sending in poor samples though.

I do plan to make my own leach and indicator but wanted to try an already made kit before trying it on my own. Not sure if that was a good idea but that's what I did. Now if I can just get it to find some gold, I'll be happy. It does dissolve gold. I used it along with a link from a gold chain to get my solution to test the indicator and my own stannous chloride tests.

I'm going to try leaching the bought ore again when I'm done playing with the last test. It is in a 1 dram glass sample bottle and it is the only one I have left. I broke the other one that came in the kit.

bmgold2


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## butcher (Dec 24, 2013)

I do not know if the Gold Hunter's Test Kit has changed chemicals or not, mine could have been The SSN/HNO3 or brine and nitric leach, its been so long ago and my memory is bad, and that seems very likely it did, I know they would have shopping problems with many of the chemical needed, and their kits would be made around that.I do not know if it was the leach or the test solution that went bad with the shelf life of the kit I had, but I do remember It did not work. 

Basically the brine and nitric leach (SSN) is an aqua regia (substitute) it is very similar to aqua regia, it would not be good long after mixing, just like aqua regia, it is gases formed that are in large part responsible for oxidation of the gold, these gases do not stay in solution long, can be driven out faster with heat, and would not have a long shelf life.

The two best known reagent to test gold in solution would be stannous chloride, and ferrous sulfate, the stannous chloride gives the violet color of colloidal gold purple of Cassius, the stannous chloride has s fairly short shelf life, especially depending on how it is made and stored, if stored in absence of air or oxygen, and with a piece of free in with a little free HCl it will have a bit longer shelf life, in the clear solution that came with the kit, I do not remember seeing any metal in solution, and the fact the solution was clear lead me to believe it was stannous chloride in the Gold Hunters test kit, ferrous sulfate or copperas would be a green solution (if not oxidized to some other salt of iron), and the test would give a brown reaction of precipitated gold, another reason I believe the kit contained SnCl2, and not FeSO4 in the kit.

I just knew I could make my own kits to do the tests.
I just soon viewed this kit like Shor's, taking common chemical and known tests and relabeling the chemical, to gain a dollar in the market.

If you cannot crush and pan visible gold, and if the ore is as high a gold content as advertized, this leads me to believe the gold is chemically bound microscopic gold in the ore, (I also assume you roasted the powdered ore before panning).

I would also roast the ore before leaching, if you do not your acid leach may not be able to pick up the gold bound up chemically like in a sulfide ore.

It does sound like Action mining is making good money on that rock, so I guess it could contain gold? Call me skeptical I do not believe rock has gold until I see it myself. :lol: 

You could also test your Gold Hunters test kit, using their leach on a known gold, and trying the test with their test solution and your own homemade SnCl2 solution. Or making up your own leach solution and test the test their test solution against your homemade.
Also testing their leach and your leach on the ore, You could even try to recover some gold from the ore with a smelt to see how that worked as opposed to leaching, also not all leaches will be effective with all ores, sometimes the ore itself can counteract the leaches ability to dissolve gold, the ores have a chemistry of their own that can affect the chemistry of the leaching solution and the gold.
Basically using different tests to find out what is working and what is not, and experimenting to try and find something that will work.


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## bmgold2 (Dec 24, 2013)

Thanks butcher,

Their indicator is clear. Somewhere I read that it contains "something" to keep it from going bad. As for the leach itself, their site states that if it goes flat you can add a little nitric acid to it to restore it. Salt water is pretty cheap and available so ...IF... you had nitric acid to add, you could just make it yourself. 

I did use their leach to dissolve some actual gold and it worked fine. Both their indicator as well as my homemade stannous chloride showed the purple or black color depending on how much gold was dissolved. What changed was when there was iron or another metal in the solution with the gold. Then their indicator gave an orange or almost brown color where my homemade stuff didn't do that. My only guess is that whatever else is in their solution is reacting with the iron.

I did roast the ground up ore but might not have done it right. What I did was to add the ore and some table salt to a stainless steel dog dish and put in in a wood furnace. I only left it in for a half hour or maybe 45 minutes. I kept checking it/stirring it and when it was hot (dish was glowing - not sure if the ore was glowing) and then cooled it down. I didn't think to dump the ore immediately into cold water so that could be part of the problem. After that, I panned (actually just fanned it around the pan since there wasn't that much in this test) and couldn't find any free gold showing up.

I have another pinch of the ore that I "roasted" in the vial along with some more leach solution and will check it out in a while to see if it caught any gold. I'll likely leave it at least overnight since it is not real warm. I'll let you know how it turns out. I need to find my propane torch and some propane to try heating up the ore quicker and easier. My oxygen tank is real low and my acetylene tank is empty or I'd have used that.

bmgold2


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## butcher (Dec 24, 2013)

For some types of ore roasting with salt can be beneficial, (depending on the ore type and the leach you planned to use), it can help to convert the gold to chloride in the high heat, a down side to this is that it can also fume off some of your gold as gold chlorides are volatile at these red hot temperatures.

Roasting sulfides in air can help to break down the sulfide bond, driving off sulfur oxide gases, sometimes these bonds are hard to break, and an iron powder can help to break the bond, gold giving up its bond with sulfide to the iron, then iron releasing them easier with the heat as sulfur dioxide gases, But of course we are adding more ore to be leached latter.

Grinding fine and roasting red hot in air or oxygen is important to break the chemical bonds, the exposure to oxygen or air is just as important as the heat needed to oxidize the ore.

Sometimes it is best to heat the ore for a while before bringing it up to red hot in the roasting procedure, to help drive of volatile gases, before oxidization in the red heat.

Oxidation can help also with iron in solution, as iron oxides (hydroxides) are not as soluble in many leaches, this can help some to lower the amount of iron your leach pulls into solution before or with your gold. it can help other to oxidize the base metals in the ore, be leached into solutions if you are pre-leaching the ore for base metals before going after the gold. 

Like double edged swords, it may work but it may be easier to cut yourself.

Ore as you know is complicated and it can complicate getting gold out, not every leach will work with every ore, and in mining many times they have to do a lot of experimenting to find a way that will work to get the gold.

Be careful with the fumes of roasting and acidifying the ore, some of these can produce extremely deadly gases, arsenic is one you would not want a lung full of.

The SSN leach would be a weak leach in my opinion, even if mixed up fresh, basically how it works is a portion of the nitric acid converts some of the salt in solution to HCl acid, this along with nitric acid forms an aqua regia, in a high brine solution, aqua regia forms gases that oxidize the gold (along with the nitric acid) the oxidized gold is picked up by chlorides in solution, when aqua regia is freshly made these gases are in solution to do work, if the aqua regia was prepared a long time before we used it it would not be as effective as we would not have these volatile gases in solution to attack the gold, this is why you always prepare your aqua regia fresh, and not make it and store it for use later. I suspect the SSN would be the same, sitting on the shelf it would not be as effective, but the salt solution could be regenerated with fresh HNO3.

The SSN leach may or may not work with your ore, or you may be leaching base metals and the leach is so loaded with base metal and there is no room for gold, or you can be getting gold into solution with your base metals from the ore...

Well sounds like you are having fun and are on the right track keep us posted, I would like to know what you get out of this ore.


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## FrugalRefiner (Dec 24, 2013)

As butcher has pointed out, roasting ores is a complicated issue. Different ores have to be treated in different ways. What works with one ore may increase your problems with a different type. There is some good information in T.K. Rose's book, _The Mettalurgy of Gold_. It's a very old book, so it is out of copyright. It is available as a free download from Google books as well as other sources.

Dave


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## bmgold2 (Dec 25, 2013)

Well, I finally got a positive test for gold from the bought ore. It's not a very dark stain but it is a light purple. I ended up using my own stannous chloride instead of the kit's indicator. The kit's indicator is still showing an orange color.

Reading through Hoke's book, it looks like stannous chloride does NOT give any color from iron, copper, zinc, nickel, or cadmium so I don't know what the kit's indicator is but that seems to have been my problem. I wonder how many of my original tests actually had a little gold in them?

I'm going to let the ore leach for another day in case it dissolves a little more gold but at least now I know there is gold in the bought ore. This ore (at least an ounce per ton) might not be the best ore for a small scale miner to deal with but I'd hate to pass it up if I had actually found it instead of bought it. I'm sure a big company would be interested in it considering they deal with much lower grade ore. I'm going to continue experimenting with it and hopefully get a little stronger indication of gold from it but considering the small amount of ore I'm dealing with in my tests, I'm happy that I got any indication of gold out of it at all.

Next step will probably be trying out some homemade leaches. My main reason for buying the kit instead of making my own in the first place was the difficulty and expense of getting nitric acid. I'm just playing around and trying to learn a little bit along the way so I can't really justify buying nitric acid since I don't have my own ore (that I know of).

bmgold2

P.S. another book I found online that has some information about roasting ore is:
Leaching Gold and Silver Ores: The Plattner and Kiss Processes. A Practical Treatise
which can be downloaded HERE:
http://www.google.com/url?sa=t&rct=...HerGSTiV8WHhfnR0XlWto8w&bvm=bv.58187178,d.cWc


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## butcher (Dec 25, 2013)

Thanks for the link to the book.
If you have too much trouble getting nitric acid you could just make your own.

I just read a little of the book you linked, what is obvious to me is they were using salt in their roasting process mainly because of the way they were going to be leaching the gold, also later in the book He speaks of where they were losing much of the gold in the ore, He traced it to the roasting process they were using, vaporizing off considerable amounts of their gold (roasting the ore with salt).
I would like to spend some time reading that book.


The stannous chloride test is extremely sensitive, it will detect very minute amounts of gold in solution.
The hard part may be to get those gold ions into solution.


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## bmgold2 (Dec 25, 2013)

Thanks again butcher,

I have everything I need to make "poorman's nitric" so I'll have to give that a try. I still have the leach from the kit that should last me for a while (unless it goes flat) since my tests are only using maybe 5-10 ml. each. Of course, I might try a larger leach once I figure out the pre-treatments needed to get the gold out of the bought ore or find some rocks that show signs of gold.

The only part of the book I read so far was the roasting part. Looks like I'll need to print out another huge book. I just printed out Hoke's book and have only just leafed through it so far although I did read some of it before. 

bmgold2


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## butcher (Dec 25, 2013)

One way to prove if the leach in your kit was a saturated salt solution, you could take a small sample of the leach, add a little silver nitrate solution, if you get a white milky solution of silver chloride, it would prove it a saturated salt (or chloride type leach).

If the leach is SSN, I do not see why you could not just add a bit of nitrate salt and a little H2SO4 to it.

Better yet just make up your own SSN Leach, with saturated NaCl and some of the poor mans HNO3 (after chilling) to remove most of the sulfate salts.

After reading Hoke's book, try the experiments in the book, these will teach you how many metals react in acids, these and the testing experiments, will be very valuable tools for you in this field of work.


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## bmgold2 (Dec 27, 2013)

Just a quick update on my experiments. I tried another test of some rocks I had. It was a piece of granite (I think) that a friend gave me that came from his hunting trip to Colorado or Wyoming (I don't remember which he said).

This rock was around a pound and a half and I am getting a light purple spot from my own stannous chloride and an orange spot from the kit's indicator. I guess I should have tried making my own indicator solution before buying the gold ore. Now I wonder if my black sands did contain gold. I already leached them once and thought they didn't contain gold due to the orange test results so I doubt I'll try again. I didn't throw any leach samples out but they are all mixed.

At least now I have enough proven ore to try making my own leach solution when the stuff I bought runs out (for testing purposes - not enough to bother recovery yet). 

Thanks for the help here.

bmgold2


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## bmgold2 (Dec 28, 2013)

Here's my results of testing to give a better idea of what I was talking about.

My positive test is not showing a lot of gold but looks like (to me) that it is a positive test. The KD-3 turned orange and did not indicate gold at all. Perhaps my leach doesn't contain enough gold to be worth showing up but I did want to know if there was ANY gold at all. My leach temperature was probably not high enough or my tiny sample just doesn't contain enough gold to show up with the kit. More experiments should get me closer to figuring this out but I'm getting closer.


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## butcher (Dec 28, 2013)

Stannous chloride is extremely sensitive for gold in solution, it does look like it reacted, but from the looks I would say you do not have much gold in solution, just enough to say there is something.

Leaching ore can be difficult, sometimes other metals in the ore would rather dissolve before the leach can attack gold, the chemistry of the ore can affect the leach, sometimes the gold can be in such a state the the acid cannot hardly reach it, or may not break the compound the gold can be locked up in. This is one reason with testing ore fire assay's normally work much better to determine if the ore contains gold.


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## bmgold2 (Dec 29, 2013)

I'll let this thread die soon but just wanted to post about one more experiment.

Last night I leached some black sands that still contained a lot of magnetic black sand. The tests started out the light pink and then got to a dark purple. This morning, the test showed NO GOLD at all.

I'm just guessing but I'm thinking the iron from the black sands got dissolved to the point where it dropped the gold back out of solution which would confirm my thoughts that the iron was keeping the gold from getting into the leach.

I'm happy that I got any indication of gold from my rocks and sand but, as seems to be the general opinion here, trying to get gold out of rocks on a small scale is just not going to pay out. It's still fun to check them out though and that was really the purpose of the test kit I bought. Recovering gold from electronic scrap might not be a whole lot better since you need a good quantity of scrap parts to get a recoverable amount of gold also. Of course, if you save the steel, aluminum, copper, etc. maybe you can make a little bit from the process. 

I'm not quite ready to give up yet but I'm considering it more a hobby than a money making process. I'm not in an area where I can go pan material out of the river with any expectation of finding gold so smashing up rocks seemed like a good idea. I spent days working in the hot Arizona desert when I first got into gold prospecting over a decade ago for a few pieces of gold that required good light and maybe a magnifying glass to see and had fun doing it so I guess this hobby is more than just getting gold. It's the adventure of FINDING it.

Thanks again,
bmgold2


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## butcher (Dec 29, 2013)

The best way to get that gold is with an education, knowing what to look for and where to find it, knowing if it is worth going after or not, knowing the value of scrap, and knowing how to recover and refine.
Basically it is the knowledge, education, and understanding that gets you gold, along with that hard work.
Gold will always be hard work to get, but without knowledge you are wasting your time trying to get it.

This is a good reason why study can be so valuable, without knowledge we can be working for nothing, or lose what gold we have, with knowledge we can determine if it is worth working for and know how to do the work.

It is about education which can be more valuable than gold, it is the knowledge that helps us to get that gold.


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## NeMonstr (Dec 29, 2013)

Make a strong solution of tin chloride. Soak paper in the solution. Drying paper. Close the paper in a jar. Store in a dry place. To use the tear off a piece. Drip solution with gold on paper.
Stored for a long time.


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