Sciencemadness Discussion Board - Cool looking sulfur crystals

Cool looking sulfur crystals

LD5050 - 6-5-2017 at 19:57

I was recrystallizing sulfur and I got some pretty cool looking crystal formations

macckone - 6-5-2017 at 20:01

Excellent!

LearnedAmateur - 8-5-2017 at 15:16

Interesting, I've found that crystals commonly form in a manner which you don't expect, depending on how pure the solute is, whether you use a seed crystal or not, and if the solution is supersaturated. Basic caffeine forms a similar structure consistently upon crystallisation, if agitated when supersaturated at room temperature. What solvent did you use - CS2, toluene, or something other? Was it disturbed or contaminated with insoluble particles? I think that would explain the needle cluster, as it radiates out from a single point which would originate at the initial nucleation site.

phlogiston - 8-5-2017 at 16:18

You'd be surprised at how complex it is sometimes to produce a specific form of crystal.

Tiny amounts of impurities can inhibit the growth of some crystal faces and promote others, giving rise to different crystal shapes.

The seed can have a dramatic effect. There have been factories where one day all of a sudden some crystallisation tanks yielded a differently crystallised product, and this 'condition' then spread to other tanks in time until they were completely unable to produce their original product.

MrHomeScientist - 9-5-2017 at 10:55

This sort of thing would go well in the Pretty Pictures thread!

LD5050 - 9-5-2017 at 13:14

Quote: Originally posted by LearnedAmateur

Interesting, I've found that crystals commonly form in a manner which you don't expect, depending on how pure the solute is, whether you use a seed crystal or not, and if the solution is supersaturated. Basic caffeine forms a similar structure consistently upon crystallisation, if agitated when supersaturated at room temperature. What solvent did you use - CS2, toluene, or something other? Was it disturbed or contaminated with insoluble particles? I think that would explain the needle cluster, as it radiates out from a single point which would originate at the initial nucleation site.

I'm impressed at your knowledge on crystal formation and you are correct on how you mentioned impurities. There actually was a bit of impurities that made it through the coffee filter which was a very fine and brown in color. This was recrystalized from xylenes that I got from the hardware store. I actually gave up on this batch because of all the impurities and set it aside to find it later filled with these cool looking crystal formations. The other more pure batches didn't grow crystals anywhere near this big.

diddi - 31-5-2017 at 17:09

where you using xylenes as solvent?

j_sum1 - 31-5-2017 at 17:41

In my experience using xylene and toluene as solvents for sulfur, it s very easy to get monoclinic crystals. The orthorhombic form seems a lot more difficult to make. Literature says that the orthorhombic form occurs when the crystallisation occurs below about 96°C. (And by literature, I mean wikipedia and other shallow sources -- which is why I have not provided a citation.)
I have not obtained orthorhombic crystals of any decent size though. It seems to be something that requires a bit of care and control.
Eventually I would like to have an example of both for my element collection -- a nest of monoclinic needles -- probably embedded in some resin and a nice large rhombic crystal -- big enough to handle without damaging easily.

diddi - 31-5-2017 at 22:05

there are many lovely sulphur forms which occur in nature j_sum. I have included then in my elements even tho they are not pure. hope to get to Mt Ijen next year to collect some.