# gold crystals for fun



## charities (Jan 22, 2012)

Just wondering if there is a market for these crystals It seem to me that I have a nack for creating crystals. Without trying. Weird huh :shock: So my question is How do I support or nurture these freaks of my lab environment?


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## Palladium (Jan 22, 2012)

Interesting ! How did you create them?


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## Photobacterium (Jan 22, 2012)

i had to look -












http://upload.wikimedia.org/wikipedia/commons/d/d7/Gold-crystals.jpg

*^ beautiful* but huge image.

what do yours look like ?


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## butcher (Jan 22, 2012)

Those are pretty, I guess I was thinking the question was asking about more of gold salt crystals, before seeing those pictures, those crystals look like elemental gold from a cell or a mine.


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## Harold_V (Jan 23, 2012)

I'm having more than just a little trouble believing that's gold. Identical to silver crystals, which makes me wonder if they are, and are gold plated. 

Not accusing anyone of anything---but to my knowledge, gold doesn't grow crystals electolytically---it deposits as nodules (typical of a Wohlwill cell). It would be interesting to learn more about this subject.

Harold


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## butcher (Jan 24, 2012)

I thought that it could be found from nature in those forms.

Editted to add link to a members web site of gold in natural form (some cleaned from rock).
http://nevada-outback-gems.com/prospect/gold_specimen/Natural_gold.htm


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## Lou (Jan 24, 2012)

Gold dendrites can indeed be grown, as can for all the platinum group metals. Silver doesn't appreciably gas phase transport like Os, Ir, Ru, Re, Pt, Pd, Rh, and Au do.


Gas phase grown large crystals of these metals are the purest sources of the metal on Earth, over zone-refined material and induction levitation.


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## Harold_V (Jan 24, 2012)

Thanks, Lou. I was speaking from my very limited knowledge on the subject, and with the knowledge that the Wohwill cell produces nodules. 

Can you possibly explain why that is? 

Off the subject, but related, in my many years of precipitating gold, on no more than about three occasions, I precipitated small crystals. Had they been much larger, they'd have displayed the true color of gold, as we know it. These were small enough to scatter light to some degree, so they weren't quite as shiny and brilliant gold colored, but much more so than the general blond material that was so familiar. It would be interesting to understand the reason that happened. 

Harold


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## HAuCl4 (Jan 25, 2012)

Lou said:


> Gold dendrites can indeed be grown, as can for all the platinum group metals. Silver doesn't appreciably gas phase transport like Os, Ir, Ru, Re, Pt, Pd, Rh, and Au do.
> 
> 
> Gas phase grown large crystals of these metals are the purest sources of the metal on Earth, over zone-refined material and induction levitation.


Are you talking sublimation?. That must take really expensive equipment to do. Or is it gas phase transport and deposition of the metal salts?. :shock:

edit: I am/was convinced that zone refining (as done for silicon boules for wafers) was the technology to use for ultimate purity of metals. Now that you speak about gas transport, that opens a new can of worms, as indeed even U235 can be enriched from its more abundant isotope using gas transport and diffussion, even as they are chemically the same, their minuscule difference in atomic weight is the basis for their physical separation.


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## HAuCl4 (Jan 26, 2012)

Harold_V said:


> Thanks, Lou. I was speaking from my very limited knowledge on the subject, and with the knowledge that the Wohwill cell produces nodules.
> 
> Can you possibly explain why that is?
> 
> ...


In my limited experience, the slower the crystals grow, the bigger they ultimately become. For example a precipitation of gold with ammonium oxalate done at near boiling temperatures will be fast, but will produce much smaller crystals than if the precipitation is done at room temperature over several days with more oxalic acid and less ammonia, and the crystals can grow much larger. The larger, slowly precipitated crystals seem to be slightly purer (and much easier to wash well).

Perhaps what you experienced was a similar effect but with your usual SO2?. Maybe you bubbled the gas at a slower rate or with the solution at a different temperature or concentration?.

In a Wohlwill cell the crystals grow much slower than in a chemical precipitation with SO2, so that would be another manifestation of the same effect.


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