Fun With Geodes

For Science Sunday this week, we broke open (quite literally), a geode kit, A, received for her birthday, a while back.

I'll admit, having spent some time living in Oregon, when I saw them, I thought they were thunder eggs. But, it turns out, while thunder eggs, the Oregon state rock, can be geodes, the Iowa state rock, not all geodes are thunder eggs.

Geodes, found elsewhere in the world, and in our kit, look like ordinary, unassuming rocks on the outside...


...but can be broken open...


...to reveal a hollow area filled with with quartz, an possibly other minerals. They are formed over time, in the hollow spaces near tree roots, or animal burrows, or in the holes left in lava, by trapped gas bubbles. Water seeps in, depositing minerals, to harden the outsides, and grow into the beautiful crystals on the inside.


Thunder eggs, are generally completely filled with agate, and are formed in rhyolitic lava flows, with water present. They are fun to study, because they are attached to Native American legends of the warring spirits on Mt. Hood, and Mt. Jefferson, who would steal them from the nests of the mythical thunder birds, to hurtle at each other.

General geodes, by comparison, seem a little dull. Though we did find a fun story, and kid friendly (if non-creationist) lesson on geodes, at MagicKey.com.

As for the kit, I noticed on Amazon, it's one of the more expensive, but better reviewed kits. We would give it a top rating, too. The geodes were good sized, and almost all had hollow spaces, with good crystal growth. And, it came with a nice write up, that explains not only the type of crystals inside the rock, but the difference between a nodule, primary, and secondary crystals - very nice.

We also tried making our own geodes in eggshells, following directions from Science Bob...


...dissolving rock salt, and cream of tarter, in separate bowls, with boiling water, and food coloring...




...and pouring the liquid, carefully into empty egg shells. You might want to check out Science Bob's blog, for actual instructions, and tips.


Sadly, our crystals were just beginning to grow, when Mr. Nobody (do you know that guy?) paid us a visit, and dumped the green, salty, and mineral laden water, all over the counter top, and side of my coffee maker.


But, maybe you get the idea, anyway.


For more science themed, fun and ideas for children, be sure to check out the Science Sunday link-up, at Adventures in Mommydom.

It's great to be a homeschooler.