Edible Metamorphic Rock Activity

Our edible metamorphic rock activity is a fun way to learn about how metamorphic rocks form. Metamorphic rocks are one of three types of rocks along with sedimentary rocks and igneous rocks.

Learning about Metamorphic Rocks

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Metamorphic rocks form when existing rocks (either sedimentary, igneous, or metamorphic) are exposed to high heat, high pressure, and/or hot mineral-rich fluids. It’s this heat and pressure that push and squish and change the rock into a new type of rock. There are different types of metamorphic rocks based on what type of rock it started as. Have you ever heard of marble? It’s just one type of metamorphic rock. Purchase a set of metamorphic rocks like the one below to help study the different types. Metamorphic rocks are difficult to find just out and about since they usually form deep within the earth’s crust or near tectonic plate boundaries (where lots of heat and pressure exist).

Edible Metamorphic Rock Activity – Make Slow Cooker Cranberry Walnut Fudge

This simple slower cooker fudge recipe is an easy way to show how metamorphic rocks form. We start with chocolate chips and pieces of chocolate. This represents sedimentary rock layers. Adding cranberries and walnuts represents the fossils that were once part of a sedimentary rock. Sometimes fossils can be found in metamorphic rock but often they are squashed and unrecognizable – kind of like when we cut into the fudge.

The heat from the slow cooker and stirring represent the heat and pressure changes that occur to make metamorphic rock. Our end product – the fudge – doesn’t look like the beginning chocolate pieces.

Ingredients for the Edible Metamorphic Rocks Cranberry Walnut Fudge

This is a version of our original slow cooker fudge recipe.

• 500 g of chocolate chips or chocolate pieces – we used a combination of dark chocolate, milk chocolate, and white chocolate
• 1 tablespoon of unsalted butter
• 1 teaspoon of vanilla extract
• 1 can sweetened condensed milk (397 g)

Instructions for Making Slow Cooker Cranberry Walnut Fudge

Add the chocolate, butter, vanilla extract, and sweetened condensed milk to your slow cooker.

Add in the cranberries and walnuts.

Heat on low for 2 hours stirring every 15 minutes. Line a square baking dish with parchment paper. Pour melted fudge into the lined baking dish. Refrigerate until set. Cut in cubes. Store in a sealed container in the refrigerator.

This is such an easy fudge recipe that kids can help add all of the ingredients to the slow cooker. It’s a bit difficult for them to stir, so that’s probably a job for an adult.

Recommended Products for Making Your Edible Metamorphic Rock

This is our favourite slow cooker – it’s large enough to contain LOTS of fudge and useful for batch cooking meals for the family as well.

So that your food doesn’t always have a lingering flavour of the last thing cooked we recommend using Slow Cooker Liners in all of your uses for the slow cooker. They will make it easier to clean too which is always a bonus.

I use a Square Cake pan when making fudge either a silicone 8inch pan or one with a removable bottom always lined with parchment paper to avoid the fudge sticking whilst it cools.

Looking for recommendations of Reading Material on Rocks then check out or Rocks, Fossils, and Earth Science Book Recommendations for Kids.

Learning about Rocks

Let your child become a Volcanologist with a Green Kids Craft Volcano Science set – with 7 different science and creative activities included this would be great to use as part of a study on Earth Science and rocks.

Become a real geologist as you and your child test and learn about rocks and minerals with this hands-on learning science kits. Containing 30 different samples and full instructions you’ll soon learn what you need to do and can then use this skills on other rocks and minerals that you find.

Add to your Non-fiction book collection with these 3 favourite books to support learning, encourage investigation and extend your and their knowledge. The first is a field guide from the National Geographic Book Range on Rocks and Minerals, with this guide it aims to get kids out, exploring and discovering more about the rocks around them. The second – a Geology Lab for Kids has 52 different science activities and experiments for kids perfect for encouraging your child to get hands-on learning about Earth Science. The last is a reference book covering rocks and minerals which will help you answer all of the inevitable questions that kids and you may have as you turn your hand to learning and exploring about rock science and geology.

More Edible Rock Activities for Kids

• Make edible sedimentary rocks to learn about how sedimentary rocks form.
• Make edible igneous rocks to learn about how igneous rocks form.
• Use candy to make an edible rock cycle.
• How about making an edible model of how mountains are made

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