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    Home / Science projects / How To Crack a Geode + Video
    • How To Crack a Geode + Video

      How To Crack a Geode + Video

      A geode looks like an ordinary igneous or sedimentary rock, but the inside is often full of crystals! You can find geodes "in the wild" in some parts of the country, or at rock shops or science supply stores.

      Watch our project video to see us crack open some geodes and find crystals inside:

      What You Need:


      related product

      Buy the supplies for this project in one convenient kit!

      Deluxe Geode Kit with Rock Pick >>



      What You Do:

      1. Place the geode inside the sock. This will help prevent rock fragments from flying and hurting you.
      2. Put the geode on a hard concrete surface, like a sidewalk, patio, or garage floor.
      3. Wearing safety goggles, hit the geode gently along the middle with the rock pick until it splits open. If you hit too hard, you may end up with lots of little pieces, so starting with gentle blows is best.
      4. Another method uses a chisel to split the geode, making it more likely to end up with two equal halves. Set the geode on the concrete, place the chisel in the middle, and tap it very gently a few times with the hammer. Turn the geode a quarter turn and do this again. Continue scoring along the circumference of the geode until you see a crack form all the way around, then pull the two halves apart. (This method works best with hollow geodes.)
      5. Examine the interior using a magnifier. Can you make out individual crystal shapes? How many different types of crystals do you notice?

      What Happened:

      A geode cracked open

      Geodes are formed when there is a hollow cavity in solid rock. This cavity can form in several ways: by a gas bubble in a lava flow, by limestone being dissolved by an acidic substance, or by a shell not being filled completely with sediment when it is fossilized. When mineral-rich ground water gets into these cavities, the minerals can form crystals, depending on the temperature, pressure, and the amount of water. (Go here to learn more about crystals.)

      Each geode is unique. Some will have large colorful crystal formations, others may have solid bands of quartz, and still others will have mineral deposits but no crystals formed yet. Sometimes a geode might be full of silt or sediment. This kind is called a "mud ball." If you are selecting your own geodes, try to choose ones that seem light for their size; these are more likely to be hollow in the center and have crystal formations.

      For a fun activity you can do with household materials, check out our Make Your Own Geode project!

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    By: Sandra
    Date: Jun 20, 2016

    How can you put a hole in a peace of geode rock for jewelry?

    By: random person
    Date: Jul 16, 2015

    I have some geodes at home. my mother says they are not crystals. but i didn’t listen and i made my own collection.

    What do i do with them? sell them, keep them. I dont know. maybe you have some ideas

    By: Fayen
    Date: Dec 25, 2014

    Thanks for the tip!