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

Are Amethysts a part of geodes?

Hi everyone! I am Tracy Jones, the Professional Geologist here at Mini Me Geology. Today’s Ask-a-Geologist question is about whether amethysts are a part of geodes or whether are there other minerals inside those rocks entirely.

Are Amethysts or other Minerals Inside a Geode?

One of our readers, David, wrote to us and was curious about geodes and the minerals inside them. He asked, “Are amethysts a 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 like 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. These cryptocrystalline layers are also called agates.

In some instances, the inside of the geode is completely filled in with agate 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.

So, yes, amethysts can be a part of geodes but you may find other crystals as well.

How to Safely Crack Open A 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.

You will often find purple amethyst, clear quartz, agate (cryptocrystalline variety of quartz), and possibly citrine inside your geodes.

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