Science Buddies: "Ask an Expert"

I have been playing around with some beginner crystal kits just for the heck of it. The current crystal that I am growing is one of those glownin the dark ones. It was growing nice and clear with sharply defined points. However, as it grew above the solution, the points are now covered with opaque, irregularly shaped globs on the points. These are hard and do not come off. Is this normal? Is this from letting it grow above the solution? Anyway to prevent this?

Hello rschlegel!

I would be happy to explain that to you! The reason that crystals grow is that they are in super salty water. The growing crystal needs to be saturated in its solution (the one you created based on the kit's directions) in order to grow properly and not have these complications you stated. I think the reason that your crystal is growing globs on the points is that it is not supposed to be above the solution. A way to prevent this is to make more of your solution and make sure your growing crystal is completely covered with it. I hope this helps you and you enjoy your journey in creating crystals!

Thank you! I was wondering if it was something along those lines. I look forward to using this info for my next crystal to see the results and compare!

I'm so glad I could help!

Hello!

To elaborate on a fellow mentor's explanation, the term for the type of solutions that crystals like to grow in, for example, the solution you created using the kit's directions is called "supersaturated." A solution becomes supersaturated when there is more solute (the material that dissolves) in the solvent (the liquid such as water). Different solutions have the ability to dissolve different amounts of solute. Once there is so much solute in a solution that no more solute can dissolve, the solution is supersaturated. Under these conditions, the excess solute crystallizes.

When a crystal grows outside of the solute, the appearance may change due to oxidation, which means the crystal is reacting with oxygen in the air and this can result in a color change. A similar phenomenon occurs when iron turns to rust (as a result of oxidation) or copper turns a blue-green color when oxidized.

Note that this is just a hypothesis and I suggest you look further into this question to find a more detailed and accurate answer!

Here's a project from Science Buddies that concerns growing crystals and can provide some more detail to help answer your question: https://www.sciencebuddies.org/science- ... background

Hope this helps!