The best (read only) ways of making a nice crystal that I can come up with, having had Chemistry up to an AP level, are gaseous deposition, which I know would work, but I don't know what exactly would need done, and I think electrolysis of a solution of Bi3+ would work. Here's how you'd do that:
First, obtain some bismuth based solder. If it helps, look for Rose's Metal. Wikipedia lists a solder alloy with the formula SnBi58 which I'd suggest using the most if you can somehow find it, alternately, a simple sample of pure bismuth metal ought to work.
Next, put that in a beaker and apply Hydrochloric acid, HCl. These are rough steps, so how much is relatively up to you. Be careful though as it is an acid. This will produce a solution of BiCl3 which just dissolves in H2O to produce the Bi3+ ions and some Cl- ions and also produce some H2 gas. If you apply a voltage of slightly more than 1V you ought to get Cl2 gas and possibly some H2 gas bubbling off the electrode and Bi crystallizing on the cathode. You would probably need a gold or platinum set of electrodes. Stay away from the cell as it operates as the Cl2 gas is very toxic and may react with the H2 gas to produce HCl in a gaseous form. As the solution in the beaker crystallizes it will also be reacting with the excess acid in the solution, so this will probably take a while for the reaction to procede to completion.
For a safer method, which I just realized would be applicable, a set of Sn electrodes would produce a galvanic cell, thus generating electricity instead of consuming it. If anyone wants to look up how to set up a galvanic cell, they can do so on their own. To make this you would need some Sn, tin, electrodes and the BiCl3 you prepared in the other method.
Though this will only get you a Bismuth crystal. The iridescence comes from the Bi2O3 coating that is effectively rust. Just let it sit out. It should eventually tarnish to that.
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Topic: How Stones/Gems/Ore/Metals look like (Read 31834 times)