Alum Crystals for Leprechaun Jewels

I thought it would be fun to do some St. Patrick's Day themed science projects, this week. I was inspired by a Steve Spangler leprechaun science kit, but wondered how much we could do on our own, with things found around the house.

To begin with, I noticed one of the ways Spangler turned an ordinary science project into a St. Patrick's Day project, was by adding some green food coloring. I wondered if it would be possible to grow green tinted alum crystals, that could double as leprechaun jewels (possible bait for a leprechaun trap, if you think the pesky little guys exist, and are inhabiting your house).

Alum is an ingredient used to make pickles crisp, meaning it's non-toxic, and also in many people's kitchens, including mine. Whether or not we could use it to grow crystals (I've had really bad luck trying to make rock candy lately, so I've lost faith in my crystal growing abilities), and whether we could make the crystals green, remained to be seen.

We measured out 2 and 1/2 tablespoons of alum, into a cereal bowl, added about 20 drops of green food coloring, and dissolved it in 1/2 cup of hot water.

The water ended up being almost black, which we were worried was too dark, so we made an additional bowl of alum water, with the tablespoon we had left. For our second bowl, we added a few drops of green food coloring, to the water, before adding the water to the alum.

We left our bowls, uncovered, and undisturbed overnight.

We were less than thrilled with what we found this morning.

There were a number of tiny crystals in our bowls, that had grown together to form one large, not particularly crystal like, blob. It was green, and sparkly, but not very jewel like.

I thought we could do better. So, after we broke the crystals apart, and picked a few out, with tweezers, to examine, we dissolved both bowls full, in water again. We dumped the alum water out onto plates, so the crystals would have more room to form. Then, we headed out to church.

When we got home this afternoon, things were looking more promising.

And, by the children's nap time, we had a couple of crystals, that while not green yet, were about the size for attracting greedy little leprechauns.

We will let the water evaporate off the rest, to see if some of the green color will settle, and dry onto our jewels.

It worked with our smaller crystals from last night. They had a nice green hue, that rubbed off when they were handled (a leprechaun trick, if ever I've seen one). But, if it doesn't work on our larger crystals, that will be okay, too. The children don't actually believe in leprechauns, and the crystals will make a lovely, octahedral treasure for our Polly Pockets.

To learn more about the science behind crystals, I would suggest watching The Magic School Bus Meets Molly Cule (you can view the entire episode, here).

It's great to be a homeschooler.