FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Hello,
You are picked by the magic of crystal. It remains to learn the laws of symmetry that allow their identification.
When I was a student, I visited (in the 50s) the Bayer plant in Leverkusen (Germany) and I saw crystals of copper sulphate 3 meters long, having crystallized in long tanks of copper.
Roger.

[kakov]

Even though we probably can not reproduce any of these in the kitchen at home, this is overwhelmingly cool stuff, it is a sublime pleasure to watch. Thanks a lot Cesar for sharing these aspects of your work with us!

[Turbo]

Roger,

In that case, the Guinness Book of World Records is wrong about the largest copper sulfate crystal!

Ed

[Cesar M. Salvan]

3 meters long copper sulfate crystals? And I dealing here with millimeter size crystals...sigh..

Kakov:

thank you very much for your appreciation!.
And don't think one cannot reproduce them at the "home-lab". Actually, the crystallization process does not require complex stuff or advanced skills (but in some cases... I did not try to obtain quartz crystals at home).

The crystallization requires just control of conditions (evaporation, temperature change...) and cleanliness. With clean stuff and patience, everybody can extend their own grown crystals collection apart from the copper sulfate, alum and alkaline phosphates, salts with a marked tendency to form big crystals. For example, I love the calcium acetate crystal shown in this thread!.
Instead to compete for the bigger copper sulfate crystal, I think is more interesting and fun to compete for the major diversity of species or for the hardest to crystallize.

For example, generate lead metal by electrochemical reduction is very easy: you just need a dish, two electrodes and a battery. But, the formation of lead crystals requires control of voltage and very clean solution and electrodes. Usually, excess of potential leads to dendrites.
The formation of dendrites or excessive nucleation (which generates masses of small crystals instead a few well formed ones) are the nightmares of the crystal enthusiast and usually are consequence of too fast temperature or concentration changes, agitation or dirty solutions.

[Mark Beregszaszi]

When it comes to growing metal crystals the easiest is growing silver branches from AgNO3 solution.

Not sure about bismuth crystals, that mey require a furnace and it is hard to obtain pure bismuth.

[Cesar M. Salvan]

Hi Mark,

Indeed to obtain silver metal is very easy, but I still can not obtain crystals, only dendrites or tree-like growths, that, senso stricto are crystals, but with a particular growing pattern. In principle, a good designed electrochemical cell should work in the home growth of nice silver crystals.

The bismuth is easy to crystallize. And its low melting point allow the crystallization at "kitchen level". A furnace is the ideal tool, not for temperature, but for control: growing good developed crystals requires room and a slow drop in temperature in the vicinity of melting point. After some trial and error, is possible to obtain beautiful centimeter size crystals using a cooking pot. Is not necessary to use high purity bismuth. The cheapest "technical" grade works fine.

[Mark Beregszaszi]

Thanks Cesar :)

I will try to obtain some bismuth and try to grow some crystals of them

[cascaillou]

Did you hear of the curse of Tutankhaillou?
That's me being burried with a necklace around my neck consisting of a beautiful cut green stone set in beryllium metal, the stone being a synthetic uranium-beryllium silicate.
Anyone daring tomb-raiding me in the next centuries will be neutron-cursed, and there start the legend, mouhahahahaha!

Time for my pills...

[trtlman]

At what temperature does bismuth melt and where can obtain some?

[Turbo]

Modern lead-free fishing sinkers are alloys of tin and bismuth. They melt under a flame.

[trtlman]

[Mark Beregszaszi]

So if I take some lead-free fishing sinkers, put them in ccHCl, then the tin will dissolve and the bismuth will remain, right?

[Turbo]

The lead-free ones tend to be brighter and shinier and they do not tarnish as dark as lead. Not sure if a stovetop would work well. I recommend working in a ventilated area just in case.

[trtlman]

After a google search stove top will melt bismuth, slowly but surely.

[trtlman]

I assume home grown silver is not real silver, otherwise people would grow their own silver instead of buying it.