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You can make your own geode using plaster of paris, alum, and food coloring.

You can make your own geode using plaster of paris, alum, and food coloring.

Anne Helmenstine
You can make your own geode using alum from your kitchen and either an eggshell or else plaster of paris to make the 'rock' for the geode or you can use a crystal geode kit. There isn't a significant difference between a totally homemade geode and one from a kit, so deciding between the two is mainly about price and convenience.

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