Gold powder to melted button ???

[Acidrain]

I have a question for you more experienced refiners....
So my observation is this; when I refine gold to high purity and the powder starts clumping together in large balls and is that perfect color, it looks like a LOT! Then when I melt it, it shrinks into a much much smaller ball vs gold powder that is a bit darker and forms much smaller clumps.
I recently ran two batches. First batch was textbook. Second batch, I fell asleep several times throughout the process, had it redisolve and had to re-recover it. First batch appeared to ve 10x larger than the second batch but when I melted them, it was only twice the weight. The perfect batch was "fluffier" than the second batch. Both turned out equally beautiful.
My question is, why would one look so much larger than the other when in powder form?

 

[BGDOCK]

Sir Fluffly’s law :
1.) The more fluffy it is the less it weighs
2.) the fluffiness volume is inversely related to its value
2.) silver cement is a great example of rule number 1 found in nature

 

[Shark]

Sir Fluffly’s law :
1.) The more fluffy it is the less it weighs
2.) the fluffiness volume is inversely related to its value
2.) silver cement is a great example of rule number 1 found in nature

Oh so true.

 

[Acidrain]

I understand what you're saying guys but I'm curious about the mechanics of why the more pure I get the gold powder, the more "fluffy" it seems.
It's SUCH a let down when I melted the first, which didn't look as pretty as powder and then melted the second which was BEAUTIFUL and looked like ten times as much but in reality, was only twice as much.

 

[Shark]

As a powder, it depends on how densely packed it is when it drops. The button in my avatar, was so compacted that it tried to dry as one lump. Usually the fluffy stuff is in fine grained powder and while clean it may not be quite as clean as the last bunch, even by 01. The remaining contaminants may play a factor as well.

 

[nickvc]

In my experience the lower concentration the gold solution is the fluffier the precipitate is, it also helps if you lightly boil your precipitate to concentrate it but make sure it’s oxidizer free.

 

[Justincase]

The thing I find interesting is the force that is in operation when gold starts to "clump".
It is the weakest intermolecular force.
London dispersion forces are temporary attractive forces that develop temporary dipole and hence they are also known as induced- dipole-induced-dipole.
When we remove enough impurities, the gold molecules can start to attract each other.
The less there is to interrupt this force the tighter those gold molecules can pull together.
I can not think of a demonstration of this force that is so easily observed.

 

[Yggdrasil]

The thing I find interesting is the force that is in operation when gold starts to "clump".
It is the weakest intermolecular force.
London dispersion forces are temporary attractive forces that develop temporary dipole and hence they are also known as induced- dipole-induced-dipole.
When we remove enough impurities, the gold molecules can start to attract each other.
The less there is to interrupt this force the tighter those gold molecules can pull together.
I can not think of a demonstration of this force that is so easily observed.

I think what happens can be compared to what happens to snow.

When the pure Gold precipitates out of solution it falls out with a "crystalline" structure.
The actual structure depends on a plethora of factors and if the structure is "small/fine" enough it will change our perception of the color.
So small spheres will seem very dark but at the same time be very compact, while branchy structures may also seem dark it will still settle much more slowly.
And all the iterations between.
If you compress this, the structure breaks and thus takes less space.
The same thing happens when melting of course.

One thing is consistent though, a gram of Gold is always the same actual volume.

It could be interesting to see microscopic images of precipitated Gold in various states though.

 

[Justincase]

I think what happens can be compared to what happens to snow.

When the pure Gold precipitates out of solution it falls out with a "crystalline" structure.
The actual structure depends on a plethora of factors and if the structure is "small/fine" enough it will change our perception of the color.
So small spheres will seem very dark but at the same time be very compact, while branchy structures may also seem dark it will still settle much more slowly.
And all the iterations between.
If you compress this, the structure breaks and thus takes less space.
The same thing happens when melting of course.

One thing is consistent though, a gram of Gold is always the same actual volume.

It could be interesting to see microscopic images of precipitated Gold in various states though.

Can you describe elemental gold precipitate as a crystalline structure before you have melted it?
"A crystalline structure is any structure of ions, molecules, or atoms that are held together in an ordered, three-dimensional arrangement."
If they do, it must be on a microscopic level.
I do fine the way different elemental particles such as Colloidal consisting of sub-micron gold.
Can anyone measure the angles and intensities of the X-ray diffraction?
A crystallographer can produce a three-dimensional picture of the density of electrons within the crystal and the positions of the atoms, as well as their chemical bonds, crystallographic disorder, and other information.
But I do not know one.

 

[Yggdrasil]

Can you describe elemental gold precipitate as a crystalline structure before you have melted it?
"A crystalline structure is any structure of ions, molecules, or atoms that are held together in an ordered, three-dimensional arrangement."
If they do, it must be on a microscopic level.
I do fine the way different elemental particles such as Colloidal consisting of sub-micron gold.
Can anyone measure the angles and intensities of the X-ray diffraction?
A crystallographer can produce a three-dimensional picture of the density of electrons within the crystal and the positions of the atoms, as well as their chemical bonds, crystallographic disorder, and other information.
But I do not know one.

Well after you have melted it it is definitively not crystalline, unless you let it cool very slow.
Just think about an ice cube, it is not in a crystalline form , but are more amorphous in composition, unless you let it form very slow.

I imagine it is in one of the crystalline forms that the conditions favors.

But in nano and or micro scale.

As the single molecules precipitates it finds a mate to coexist with and so on.
Most molecules "hate" to be alone so they always agglomerate with others until the conditions forbid it.
These temporary structures probably do not look like the more permanent crystalline structures,
as they are comprised of millions of micro/nano crystals loosely connected,
like branches or maybe even like snow crystals.

 

[Justincase]

Well after you have melted it it is definitively not crystalline, unless you let it cool very slow.
Just think about an ice cube, it is not in a crystalline form , but are more amorphous in composition, unless you let it form very slow.

I imagine it is in one of the crystalline forms that the conditions favors.

But in nano and or micro scale.

As the single molecules precipitates it finds a mate to coexist with and so on.
Most molecules "hate" to be alone so they always agglomerate with others until the conditions forbid it.
These temporary structures probably do not look like the more permanent crystalline structures,
as they are comprised of millions of micro/nano crystals loosely connected,
like branches or maybe even like snow crystals.

Sure look like crystal structures to me.

 

[Justincase]

 

[Yggdrasil]

Sure look like crystal structures to me.
View attachment 65046

Nano crystals.
and as you see they are just a part of the whole, so these regions probably did not cool as fast as the rest.
And when you look at the whole you need it to cool very slowly to get crystal growth that will be visible to the naked eye.

 

[Justincase]

Nano crystals.
and as you see they are just a part of the whole, so these regions probably did not cool as fast as the rest.
And when you look at the whole you need it to cool very slowly to get crystal growth that will be visible to the naked eye.

Yes we have a great control over the size of the crystals in our metal products.
Much like steel, the impurities and cooling time.
The size of the resulting crystal greatly affects the property of the end product.
Two sample of exactly the same elemental makeup can have drastically different mechanical properties because of this.
Gold cools down in waves as it crystallizes, this is why we get the contraction lines on very pure hand poured bars.
Size is important, but all sizes are quite beautiful in their own way.
I know of only two places that have naturally occurring gold crystals you can see with the naked eye.
Hopes Nose near me in Torque and a mine in the US.

 

[Yggdrasil]

Yes we have a great control over the size of the crystals in our metal products.
Much like steel, the impurities and cooling time.
The size of the resulting crystal greatly affects the property of the end product.
Two sample of exactly the same elemental makeup can have drastically different mechanical properties because of this.
Gold cools down in waves as it crystallizes, this is why we get the contraction lines on very pure hand poured bars.
Size is important, but all sizes are quite beautiful in their own way.
I know of only two places that have naturally occurring gold crystals you can see with the naked eye.
Hopes Nose near me in Torque and a mine in the US.

It is very rare indeed, but I believe it are found more spread than that.
Anyway this one is supposedly the rarest of them all.
https://www.nationalgeographic.com/science/article/worlds-rarest-form-natural-gold-reveals-secrets

 

[Justincase]

Gold from Hopes Nose, Torquay, Devon collected by Richard W. Barstow (1945 - 1982)

 

[Yggdrasil]

View attachment 65048

Beautiful indeed

 

[Acidrain]

This has turned into a pretty cool thread

 

[goldshark]

The gap, or area between particles, is called the interstices. The finer the individual grain size, the more space between particles. To get a denser pack, you need a variety of different si

 

[Justincase]

The gap, or area between particles, is called the interstices. The finer the individual grain size, the more space between particles. To get a denser pack, you need a variety of different si

How do the gold molecules arrange themeless as they come out of solution?
Is it a loosely formed cogent of molecules clumped by weak molecular attraction.
Or do they form distinct crystalline structure of variable sizes dependent on the local environment?
Obviously if we could precipitate the largest partial possible it would make our job easier.
An interesting question.