# Slag after melting pins



## Marcel (Mar 19, 2012)

Just to experiment I have melted 4,2 g of very high grade pins.
Used a tip of a teaspoon of borax, twice.
Used my new torch and my new quartzglass crucible.
Melted nicely and fast with a uniform red color.
The result was a nice button with high grade gold on the bottom, but a nasty black slag on top.






I expected the most of the button to be copper and the gold has sunk to the bottom, but when I started filing the black slag it appeared, that there was also gold underneath.
I remelted the button with a torch (propane/butane) and let it melt completly.
Same effect, nice gold on teh bottom but a black coating all over.
Did drop it in some rejuvenated diluted AP solution and put it into ultrasonic to see if it could be removed. negative.
Instead the gold appearance vanished and the button got a thin black layer again. 
Used my dremel to file and poslih the button and now it looks like a massive low karat gold piece. Very hard though, so there must be some other metal involved that hardens the gold.


Now my question of the day: What can this black coating be? How can I remove it after melting, without disolving the thin yellow gold layer at the bottom as well ?
Btw: At the moment I am reading tutorial, learning, trying out things that´s why I became silent for the moment ;-)

Edit:
Added to pics with a piece of copper to compare the color, because the gold appeares to be reddish, but is not so much red:


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## Barren Realms 007 (Mar 19, 2012)

Now you are learning why material of this kind is not melted. How much gold have you lost playing with the slag? When you process this button your gold will be in small specks insted of flakes that you can identify.


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## samuel-a (Mar 19, 2012)

Marcel

It is always nice to learn new things by experience, keep it up.

To answer some of your questions...
Copper while molten will form black oxides, especially with a torch melt.

It seems to me that this melt is not alloyed consistantly, that's why you find odd things...
The melting temp could have not been high enough

Also remember that these pins may contain some zinc, which can couse a golden skin effect.
You can clean the slag, oxides and 'golden' zinc with hot dilute sulfuric acid or HCl.

For your sake, i hope you melt this kind of stuff under a vent.


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## Geo (Mar 19, 2012)

is there a reason other than just playing for melting those beautiful pins. are you trying to make a karat gold alloy? if so, theres just not enough gold on the plating for that. i wouldn't do that to a large amount because when you process the pins either in the cell (which is best) or AP you will have mostly gold in an easy to work form.with a lump like that your work has doubled or more.


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## Marcel (Mar 19, 2012)

Barren Realms 007 said:


> Now you are learning why material of this kind is not melted. How much gold have you lost playing with the slag?



That is true, but wont happen again. I am testing my new tools and equipment. I have never worked with a torch, borax etc. and these high temperatures before, so I decided to use a few grams of pins instead of pure gold for try-outs. If I mess them up, won´t hurt too much. I want to get a "feeling" for the work with the torch, so I can better decide which way to go.
My new furnace is on the way, and there is much to learn and understand about melting, the material and the behaviour/problems before I can start the "big ones".

@Sam: Thanks, that all makes sense and explains it. Since we had a sunny day, but will consider your safety advice concerning fumes. I didnt see and smell much of that, so I was not too aware of this.

I am a person who better memorizes things that I did with my own hands, rather than reading about them.
Concerning material: I sell it, since I got quite some stock of different types and I will use the buttons to show customers how the molden material looks.


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## Marcel (Mar 19, 2012)

Geo said:


> is there a reason other than just playing for melting those beautiful pins. are you trying to make a karat gold alloy? if so, theres just not enough gold on the plating for that. i wouldn't do that to a large amount because when you process the pins either in the cell (which is best) or AP you will have mostly gold in an easy to work form.with a lump like that your work has doubled or more.


Ok,ok I messed them up!
But hey, can I be forgiven please?
The pins are intended for AP this weekend. I try to process 1 Kg and I hope it will be all good and not end up in my solution.


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## ComputerHoarder (Apr 16, 2012)

Marcel said:


> Geo said:
> 
> 
> > is there a reason other than just playing for melting those beautiful pins. are you trying to make a karat gold alloy? if so, theres just not enough gold on the plating for that. i wouldn't do that to a large amount because when you process the pins either in the cell (which is best) or AP you will have mostly gold in an easy to work form.with a lump like that your work has doubled or more.
> ...



though i may not have much say in this matter, you are forgiven, seems like a mistake i would make, and hey we are all human afterall


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## Marcel (Apr 16, 2012)

Thank you so much for forgiving me. This particular piece went to my probe collection, I had it examinated with an XRF by the way and it showed lower than 1% Au content. So it did have a useful mission after all.


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## samuel-a (Apr 17, 2012)

Marcel said:


> Thank you so much for forgiving me. This particular piece went to my probe collection, I had it examinated with an XRF by the way and it showed lower than 1% Au content. So it did have a useful mission after all.



Do you happen to remember the Zinc presence ?


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## Harold_V (Apr 18, 2012)

Marcel said:


> The result was a nice button with high grade gold on the bottom, but a nasty black slag on top.


Please tell me that you're just joking. Why do you think there's gold on the bottom? It is simply protected from atmosphere, thus is is not oxidized. 



> What can this black coating be?


Can you say copper oxide?



> How can I remove it after melting, without dissolving the thin yellow gold layer at the bottom as well ?


You do NOT have a thin gold layer on the bottom. That's all in your mind. Pickle the button in dilute sulfuric acid, which will dissolve the copper oxide, leaving behind clean metals. Note that the gold should be well mixed with the alloy (most likely copper and zinc), and that it does NOT stratify. Why would it?

Harold


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## dtectr (Apr 18, 2012)

Since I'm using my dumb phone I won't take time to quote and reply to all the poor advice marcelle has been given. 
No one should encourage am inexperienced person to waste fuel, time and materials as he has just done. This is not standard practice for anyone on the scale he is attempting. Nor would anyone be interested in buying globs like this. Your torch set up sounds like it lacks btus sufficient to alloy this mess. You probably used the oxidizing portion of your flame to get it to melt, but did it also without a proper flux to shield it from oxidation. 
The math:
Let's imagine the pins are square, 0.10" wide by 1" long. The plating could be 20microinches thick (0.0002" - my fractions are a little rusty - anyone want to check my math? ). That is per pin, multiply by number of pins per gram, ounce or whatever. The point is, there's not much gold. Even as a dore' bar the gold would be considered a contaminant.
Composition :
The majority of the pins are often brass or bronze. Both of which appear "gold colored" but when next to gold is quite obviously different. They do contain zinc and tin, respectively and make them yellow. 
The value of this "experiment":
Learning to do something the wrong way so you'll know how to do it the right way is like contracting an STD to learn how not contract an STD. 
The reason I go on and on in threads like this which, intentionally or not, promote bad practice as well as bad science, is that they seem to be inspired by others like it, in this case "4-1/2 lbs" post on stratification. 
Barren harold and one other (was that you, nick?) told you what you needed to hear, even if you don't want to hear it, take time to learn good practice and you will have beautiful gold results.
Edit grammar


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## samuel-a (Apr 18, 2012)

dtectr said:


> Since I'm using my dumb phone I won't take time to quote and reply to all the poor advice marcelle has been given.
> No one should encourage am inexperienced person to waste fuel, time and materials as he has just done. This is not standard practice for anyone on the scale he is attempting. Nor would anyone be interested in buying globs like this. Your torch set up sounds like it lacks btus sufficient to alloy this mess. You probably used the oxidizing portion of your flame to get it to melt, but did it also without a proper flux to shield it from oxidation.
> The math:
> Let's imagine the pins are square, 0.10" wide by 1" long. The plating could be 20microinches thick (0.0002" - my fractions are a little rusty - anyone want to check my math? ). That is per pin, multiply by number of pins per gram, ounce or whatever. The point is, there's not much gold. Even as a dore' bar the gold would be considered a contaminant.
> ...



I'd assume this was directd to me (and currect me if i'm wrong):
I see nothing wrong with experimenting, we all do that. Though, I do advocate one should do his homework both on the procedure on hand and safety beforehand and i do agree Marcel haven't done his, or done so poorly.
Just because someone tried something before, it doesn't mean i (or anyone else for that matter) would not want to see the results with my own eyes.
Experiments are key part of our life, without it, we wouldn't be where we are. I know you know that so i don't see the point to get all philosophical on you.

I find that odd that you have totally disregarded the second answer in this thread (made by me), which included all of the same info including a safety note.
To be honest, i find it very demeaning that you and Harold chose to repeat the same data which was already been given (and i assume been digested by the OP) for the second and third time.

You might care and you might not.
Unless i didn't understand correctly what you and Harold wrote, i find it quite offensive, both toward Marcel and myself.

Peace.


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## Harold_V (Apr 19, 2012)

samuel-a said:


> I find that odd that you have totally disregarded the second answer in this thread (made by me), which included all of the same info including a safety note.
> To be honest, i find it very demeaning that you and Harold chose to repeat the same data which was already been given (and i assume been digested by the OP) for the second and third time.


I find it very demeaning that you feel that you are the only one that is entitled to speak one's mind, that anyone repeating any of your thoughts is, somehow, breaking one of the rules of posting on this forum. 

In my case, I stated what I did because the information that was forthcoming was not answering the question-----a response to the false notion that gold, somehow, mysteriously stratifies. I try to speak in complete sentences, so that my words flow smoothly and have meaning. That may not always be the case, but if you think for even one moment that I am to remain silent because you have already made a comment, you are sadly mistaken. That's not going to happen, nor am I going to tolerate your attitude. That's what *I* find offensive. 



> Unless i didn't understand correctly what you and Harold wrote, i find it quite offensive, both toward Marcel and myself.


This is a forum in which everyone is free to contribute--even if a thought has been conveyed more than once. That's what we do here--we talk. If you find that offensive, please note that you are not bound to contribute, or, for that matter, to even read the forum. If you hope to continue, I fully expect you'll do so with the understanding that you do not have pertinent rights on comments, that others may share your views, or not, and may voice them accordingly, or not. 



> Peace.


We shall see, won't we? If you fire another shot, I expect that's not going to be the case. 

A parting shot. I have taken note that on at least one other occasion, you have posted in such a way that I could easily conclude that you are attempting to undermine the purpose of this forum. I expect you'll understand that I take exception to that assumption, assuming it's true. 

Harold


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## samuel-a (Apr 19, 2012)

Harold_V said:


> samuel-a said:
> 
> 
> > I find that odd that you have totally disregarded the second answer in this thread (made by me), which included all of the same info including a safety note.
> ...



Again, my point is misunderstood, maybe it's my bad ability to pronounce myself in english.
Did i ever said no one can answer beside me? NO, but i do wonder how come the same info and reservations written in the first and second posts were practically dismissed...
Though i find repetition pointless, i'm certainly not the one who can (or want) to tell others what and where to say what's on their mind. I have well over 1400 posts that proves i know my place. But i do resent the spirit of which they are given in this particular thread.
You know, kinda ironic you brought up this discussion toady of all days. Today we state the national Holocaust Remembrance Day, many millions were wiped out the face of the earth basically because they couldn't defend themselves and speak up, that's including my grandmother and grandfather's entire families.
Beleive you me, i know what freedom of speach is about. I strongly believe anyone should say what's on their mind on any subject be it politics and all the way to technical data, but there's a way to say things without humiliating the other side, even bad things... There's always a way.
I will however offer sincere my apology if it might seem that i wanted to shut you up (or others). That was not my point!

You said so your self, what we do here is --we talk. So i did.


Harold_V said:


> We shall see, won't we? If you fire another shot, I expect that's not going to be the case.


By threatening me not to answer, you are basically shutting me up, not the other way around...
If you would consider me explaining my self better as another shot at you, then i never really had a chance, didn't i ?



Harold_V said:


> A parting shot. I have taken note that on at least one other occasion, you have posted in such a way that I could easily conclude that you are attempting to undermine the purpose of this forum. I expect you'll understand that I take exception to that assumption, assuming it's true.


Not true. I don't know how you got to this conclusion. I think my ongoing participation in this forum for the last 2 1/2 years proves otherwise.
Perhaps you would like to share with me privetly what posts i made before which lead you to think this way about me. 

To conclude and further sharpen my point i'll say this:
I have absolutely no problem with the concept of forums and mind sharing and never had before.
Sometimes regular words and sentences can offend others just as cursing does and maybe even more. You can damn well count on it that i will speak my mind in such cases, no matter who said those things, mod or not. Had you decide to ban me because i spoke my mind, so be it.


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## dtectr (Apr 19, 2012)

My friend
This forum has meant a huge difference, financially and otherwise, to my family and me. That's due, primarily, to the quality of information, as well as its high standard - that is what sets it apart from other forums & venues.

That this is recognized as THE authority on all things precious metals related, was illustrated by a recent exchange between my friend, a jeweler and his supplier of plating solutions. They are a well-respected, established supplier in the industry, not a "mom and pop shop", as the saying goes. When we were discussing the possibility of refining/recycling his spent rhodium plating solution, his rep recommended, not only this forum for guidance, but named one of the moderators as a resource, as well.

Maybe we should have a place on the forum where members can post their very (and slightly) dangerous experiments, a place that other, less experienced visitors won't think it is recommended or endorsed. Until such a time, though, given our international reputation, if they appear here, uncorrected, it appears that we endorse them. I can't have that on my conscience.

A post, the size of mine on this thread, took nearly an hour and a half to complete, since I have only a cellphone with a numbered key pad for internet access. I hope that expresses my concern for the safety of those exposed to it. [Today I am using my friends computer, so this has only taken me 20 minutes.]

On a completely unrelated note, my heart and my prayers go out to you and your family on this memorial day. We have accomplished on this forum what human endeavors have completely failed, often with deadly results, to do, that is to unite persons from varying gender, racial, tribal, national and religious backgrounds for a common goal. Maybe GRF won't save the world, but it does make it a little better to live in, I believe.

'Nuff said
dtectr


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## Harold_V (Apr 20, 2012)

samuel-a said:


> Again, my point is misunderstood, maybe it's my bad ability to pronounce myself in english.


Don't think so. You clearly stated "To be honest, i find it very demeaning that you and Harold chose to repeat the same data which was already been given"

How am I, or anyone, expected to interpret your words? You made it perfectly clear that you were offended because two of us repeated something you stated. We were called out BECAUSE the words were repeated, yet you still don't see that you had encouraged a reader to pursue something that isn't beneficial, and did not answer the question---chiefly that metals do not (normally) stratify. 



> Did i ever said no one can answer beside me? NO, but i do wonder how come the same info and reservations written in the first and second posts were practically dismissed...


Please point out to me where you were dismissed by any of my comments in the post in question. I may be an insensitive clod, but I clearly do not see a sign that I did so. I do see, clearly, that I bolstered what you had said by repeating what you had said. I'm at a loss to understand how that diminishes your comment(s). 



> Though i find repetition pointless


Can I interpret that as you saying that nothing is worth repeating? Do you not understand that some of us (myself in particular) often must read a subject many times before the true meaning sinks in? You may be gifted with the ability to grasp things with one iteration---but not everyone does. Repetition is key to learning in such a case. I offer you as a prime example, Hoke's book. She repeats the same information time and again, which I found to be very helpful in my learning. 



> You know, kinda ironic you brought up this discussion toady of all days. Today we state the national Holocaust Remembrance Day, many millions were wiped out the face of the earth basically because they couldn't defend themselves and speak up, that's including my grandmother and grandfather's entire families.


Know that I am sympathetic. The atrocities committed are despicable and never should have happened. Know, also, that I am not anti-Semitic***. I have great admiration for the Jewish people and respect their contributions to civilized society. However, please don't make this an ethnic issue, for that is not the case. 



> Beleive you me, i know what freedom of speach is about. I strongly believe anyone should say what's on their mind on any subject be it politics and all the way to technical data, but there's a way to say things without humiliating the other side, even bad things... There's always a way.
> I will however offer sincere my apology if it might seem that i wanted to shut you up (or others). That was not my point!


Well, to be quite frank, I don't understand your point. You have complained that your post was ignored (how could it be when it was repeated by others), and then you accuse them of doing something that was not done. I sense your sensitivity here is in not being quoted when comments were repeated, that you were, somehow, slighted. That was not my intention, but right now I feel I should have taken you to task for not providing the one thing that was badly needed---the comment that gold doesn't stratify--that there was a clear misunderstanding, or a misinterpretation of the signs that were being evaluated. Instead, you offered encouragement to continue the course, that it was, somehow, a great learning experience. What you failed to mention is that the learning experience would have proven to be very negative--that gold that is so finely divided (1% content) is a curse to process. Anyone with experience in processing low grade wastes understands that it's a good idea to not break up the gold to fine particles, which are not easily separated from the solution. That's precisely the case when melting pins, and there's no benefit in melting them even if that wasn't the case. People come to this forum to learn----they should be encouraged to learn what works, with descriptions of what's wrong with things that don't work. 

I also tend to discourage the notion that these guys should experiment. Why should they? What do you expect they will learn? Do you really think that a guy that has no clue is going to revolutionize the refining process? If nothing else, each reader should be encouraged to stick to methods that are known to work, methods that have predictable results, so they become familiar with processing. Then, when they have an understanding of what to expect, they may benefit by experimenting---but without a basic knowledge, they aren't qualified to know when they have improved a process, or not. What generally happens is they turn to the forum for guidance after their attempts fail. They have now learned what NOT to do, but they still don't know WHAT to do. I don't see that as a positive attribute. 



Harold_V said:


> We shall see, won't we? If you fire another shot, I expect that's not going to be the case.





Samuel said:


> By threatening me not to answer, you are basically shutting me up, not the other way around...


Perhaps the concept of discussing without making accusations is a stranger to you. You fired a shot with your first post, one that was not appreciated. If you can't discuss issues without making accusations, you can expect that I am not going to be kind. You made it perfectly clear that you were offended---by something that was not, and is not, an offensive matter. For that matter, I didn't even address you, so how can you make this a personal affront? I don't recall mentioning your name, yet you felt free to call me out. You did so because I posted. Ergo, I must conclude that I shouldn't have done so (by your measure). 

Understand that I have a very low threshold for such behavior. You came across as being wronged, that you had already spoken and others had no right to repeat anything you had said. That is how I interpreted what you said, above. (To be honest, i find it very demeaning that you and Harold chose to repeat the same data which was already been given)



Harold_V said:


> A parting shot. I have taken note that on at least one other occasion, you have posted in such a way that I could easily conclude that you are attempting to undermine the purpose of this forum. I expect you'll understand that I take exception to that assumption, assuming it's true.





Samuel said:


> Not true. I don't know how you got to this conclusion. I think my ongoing participation in this forum for the last 2 1/2 years proves otherwise.
> Perhaps you would like to share with me privetly what posts i made before which lead you to think this way about me.


A PM will follow. 



Samuel said:


> To conclude and further sharpen my point i'll say this:
> I have absolutely no problem with the concept of forums and mind sharing and never had before.
> Sometimes regular words and sentences can offend others just as cursing does and maybe even more. You can damn well count on it that i will speak my mind in such cases, no matter who said those things, mod or not. Had you decide to ban me because i spoke my mind, so be it.


Lets get one thing straight. None of the readers are free to speak their minds here, although that demands an explanation. You are free to voice your opinion so long as it does not cross the line, where it becomes a personal attack. Feel free to air your views, but do so without accusations. Understand that you are not free to scream FIRE when there isn't one. Understand that you are not free to use profanity (you are not being accused). Understand that you are not free to discuss politics (you are not being accused). Understand that you are not free to discuss religion (you are not being accused). In other words, there are limitations to what you are free to post--and there are those who look after this forum that have the power to silence you when you are out of line. Were that not the case, this forum would have, long ago, succumbed to the wise guys that live to be disruptive (you are not being accused). So then, you should have a clear understanding that you can expect others to parrot something you've said--and that it does not mean that you are being slighted. You can expect that others may take exception to something you've said--and they may wish to ask for clarification. You may find that some folks simply won't agree with something you said (I don't agree with your admonishment for the newbie to experiment--he has more than enough on his plate in trying to learn what works, without clouding his/her thoughts with things that don't). I have a saying that I love to pass around--don't re-invent the wheel--it's sufficiently round as is. Bottom line with experimentation is ---one should be able to walk before attempting to run. I don't find that unreasonable. 

Harold

Edit: *** I want to make it perfectly clear that I was never accused of being anti-Semitic. I made mention to bolster the fact that I am not bigoted (at least in that regard!)


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## domperignon (Sep 11, 2013)

Wow have a Kit-Kat lads!

Dominic


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## Lou (Sep 11, 2013)

Thanks for the thread resurrection.


Insofar as melting pins goes...do it all the time. Most economical, safe way to do them (in my opinion) is to melt and electrowin the copper. That and you can know what you are expecting at the back end, after the anode bags are burned.


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## Harold_V (Sep 12, 2013)

Lou said:


> Insofar as melting pins goes...do it all the time. Most economical, safe way to do them (in my opinion) is to melt and electrowin the copper. That and you can know what you are expecting at the back end, after the anode bags are burned.


Not being a stranger to the operation of a copper cell, I'm curious how you deal with the contamination of your electrolyte from the included zinc. 

There is little benefit in melting pins if they are to be processed by dissolution of the base metals. That was my point. The problems encountered by electrolytic parting may not be easily overcome by the novice. In smelting, troublesome elements are often removed, so the feed stock is far more friendly to the parting process when it's done electrolytically. 

When one melts, the resulting finely divided gold can be difficult to recover, and you risk a solution contaminated with tin, making filtration difficult. I still maintain that melting pins should not be a part of processing for the novice. 

I welcome opposing views, with explanations. 

Harold


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## niteliteone (Sep 12, 2013)

A day or so ago I read where a member suggested adding silver to a mix of iron and gold, as this would separate to 2 metals when melted and poured into a cone mold since silver has a greater affinity to attract gold than the iron and silver has no desire to mix with the iron, thus separating the gold from the iron. (I hope this makes since)

Could something like this have the same effect with pins ???


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## Platdigger (Sep 12, 2013)

You would then have an alloy of copper, silver and gold. Plus any zinc or tin you may have.
Much like rings and such. Just not as pretty.


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## niteliteone (Sep 12, 2013)

Platdigger said:


> You would then have an alloy of copper, silver and gold. Plus any zinc or tin you may have.
> Much like rings and such. Just not as pretty.


So it would form a "blended" alloy and Not separate like the iron, silver, gold mix would ???
Well not the answer I was hoping for. Good thing I asked before trying.


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## Harold_V (Sep 12, 2013)

Key to the gold/silver/iron mix is that silver and iron do not readily alloy. That's not the case with other elements, so if you mix tin or zinc in the alloy in question, they will readily mix to a homogeneous alloy. You can not count on melting to separate most (metallic) elements from one another. 

You're likely to get a conflicting point of view on the alloy being homogeneous, as there is some evidence to support the notion that an alloy isn't necessarily homogeneous unless very well mixed (such as when melted by induction), but the variations one may discover are due to poor mixing, not because the elements choose to stratify upon pouring. The bonding forces are far greater than the force of gravity, so stratification would be extremely unusual with most metals. 

Harold


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## niteliteone (Sep 12, 2013)

Thanks Harold.
I now remember (with your help 8) ) when I read about the mix, it was pointed out the resistance to alloy between the iron and silver and that was what made the silver separate the iron from the gold.


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