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We went on a family trip last month to Moab. It is a city in southern Utah that has all of these amazing rock formations. While we were there we went to this fun rock shop where you can buy a geode (a rock with crystals inside) and they will crack it open right there for you. My kids thought this was pretty cool! Soon after that, I came across a tutorial from How to Cook That explaining how to make a Rock Candy Geode. We had to try it out! We made ours with fondant and did three different colors of geodes. They turned out great!
How to Make Rock Candy Geodes
To make the rock candy geodes you need fondant. You can buy it premade, or make it yourself with marshmallows and powdered sugar. It is quite simple & much cheaper to make yourself. Plus, it tastes a million times better.
Marshmallow Fondant Recipe:
1 pound of marshmallows
About 1/2 c. shortening
2 pounds of powdered sugar
4 Tbsp water
In a microwave in a large bowl, melt the marshmallows with 2 Tbsp or water. Heat them 30 seconds at a time and stir in between. It ended up being about 2 1/2 minutes I think. They just need to be all the way melted.
Mix in about half of the powdered sugar with a big spoon. When you have mixed it as well as you can, add in the rest of the sugar. You will want to coat your hands with shortening and just knead it by hand. It is super sticky, so you definitely want your hands greased. And the counter. And any other surface it touches. 😉
If it is really sticky, add little more powdered sugar.. If it is really dry, add in the remaining water. It should be about the consistency of play-dough when you are done.
We colored half of our fondant and left the other half white. The best way to color fondant is with gel food coloring. I used black & brown and mixed it to make it rock-like. Then we layered it with the white part. The kids wanted it marbled looking.
Roll it out and fit it into a small bowl. We divided ours into three small ramekin dishes. We lined them with foil first, then pressed in the pieces of fondant. This forms the outer rock part.
For the crystalized part, you just make a sugar water solution. We used 1 c. of water and 2 c. white sugar. Cook it in a small pot until the sugar is completely dissolved. Add in any coloring you would like to use. If you are doing different colors, divide them out first. Pour the sugar water into the hollow of the rock part.
Wrap the entire bowl in foil and seal it up. Let it set for about 3 days. The sugar will crystalize. You can open it and peek, but watch out for spilling! It get’s messy. (experience) After a couple of days, pour out the extra liquid and let it dry opened.
Want more geology education ideas? Check out my Identify Rocks With Kids post. It has a fun printable!
Want more edible education ideas? I have a post with 100 of them!