We’re currently studying the rock cycle in our homeschool and just learned about the different types of igneous rock. I came up with this idea for making Extrusive Igneous Rock Cookies to add some fun. It was such a hit that I thought I’d share.
Igneous comes from the Latin ignis, meaning fire, and igneous rocks are formed from magma. There are two main types of igneous rocks:
Extrusive rocks are formed from lava that cools above the earth’s surface. So, technically they are volcanic rocks. Some of these rocks cool very quickly and are smooth and hard, like obsidian (also known as volcanic glass). But other volcanic rocks, like pumice, are very lightweight with an almost foamy appearance and are easy to crush. Isn’t it amazing how these two types of come from the same place (the heart of a volcano) and yet look completely different from each other?
I am using Considering God’s Creation as a guide for my middle kids’ science studies this year. One of the activities that was suggested to illustrate the difference between pumice and obsidian was to take some eggs whites (smooth and glassy looking like obsidian) and beating them into whipped egg whites (lightweight and foamy like pumice).
But why go to all that trouble to beat egg whites if you can take a few extra steps and make…
Extrusive Igneous Rock Cookies….
aka Coconut Chocolate Chip Meringue Cookies?
They do look just like rocks, don’t they?
I promise, they taste pretty good. They have a slightly chewy texture from the coconut, but the meringue gives it the airy crumbly texture of well…pumice.
Note: this recipe is adapted from The Joy of Cooking by Irma S. Rombauer and Marion Rombauer Becker, but the original inspiration came from my fond remembrance of the chocolate chip meringue cookies my grandma used to make.
- 1 c granulated white sugar
- 3 egg whites
- 1/8 tsp salt
- 1 tsp vanilla extract
- 1 c shredded coconut
- 1 c mini chocolate chips
2. Add egg whites and salt to medium to large mixing bowl. Beat at high speed until stiff peaks form. I used a stand mixer, but a hand mixer will work. An egg whisk will also work if you have a strong arm.
3. Slowly pour in the sugar while continuing to beat the egg whites. The original recipe says to sift the sugar first---I did not find this necessary, but you could sift the sugar if you need an extra kid job.
4. Once the sugar is beaten in, stop the mixer and remove it from the stand. Gently fold in the coconut and then the mini chocolate chips just until they are even distributed.
5. Drop the batter by spoonfuls onto the parchment lined baking sheets. The original recipe specified teaspoonfuls and also said we would get about 50 cookies. We actually got 27 cookies, so our spoonfuls were obviously much larger. It worked fine.
6. Bake for approximately 30 minutes or until very lightly browned and firm to the touch (careful---they will have a crisp exterior, but if you push too hard they will crush). 30 minutes was perfect for our bigger cookies, so if yours are smaller, you may want to try less time and keep an eye on them.
7. Transfer to cooling racks to cool. I recommend allowing these to cool completely before sampling.
This is a great baking project to do with kids.
You can have a child separate the eggs. Another child measure out the sugar. Another child carefully pour the sugar into the bowl while it mixes. And all the children scoop the batter onto the cookie sheets. You get the idea.
Are you studying rocks in your homeschool? Be sure to pin this for later.
And for fun, here’s a picture of another lava rock: