Ask-A-Geologist #7: Are amethysts part of geodes or are the minerals in geodes different?

Hi everyone! I am Tracy Barnhart, the Professional Geologist here at Mini Me Geology. Today’s reader question is about geodes.

David asked:  Are amethysts part of geodes or are the minerals in geodes different?



Hi David, geodes can contain amethyst crystals. These unique samples form in open holes in sedimentary rocks such as limestone or igneous rocks likes basalt. Mineral rich water seeps into the holes and fills the void. Minerals such as quartz, amethyst and citrine fill the hole and deposit layers of tiny crystals, called cryptocrystalline minerals in bands around the inside of the hole. In some instances, the inside of the geode is completely filled in with the minerals. In others, large crystals will form in the center on top of the cryptocrystalline layers leaving perfect, or semi perfect crystals behind with some space inside the geode.

Now, to safely open a geode, take the rock and wrap it in an old towel or sock. Make sure that is one that you don’t mind destroying because it will likely be ruined. Wrap the towel, put on your safety goggles to protect your eyes and gently hit the rock until you hear or feel it crack. Carefully unwrap the geode because it will be sharp and see the crystals inside.

Remember to keep your questions coming in through the dig into geology section on our website or email us at Please comment below and subscribe to our channel so that you get the next installment of ask a geologist. Until next time, rock on everybody.


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