What is a Geode?
From the outside, geodes look like unremarkable, lumpy limestone or volcanic rocks. But cracking them open reveals a hollow cavity lined with spectacular crystals—most commonly quartz, amethyst, or calcite.
How They Form
Geode formation begins with a cavity in the earth. This can be a gas bubble in volcanic rock or an animal burrow in a sedimentary bed. As mineral-rich groundwater slowly seeps through the porous rock casing into the hollow space, layer upon layer of minerals are deposited over millions of years.
The outer layer, usually chalcedony, forms a hard shell. As water continues to deposit silicates, perfect crystal structures grow inwards towards the center. The result is a natural, breathtaking treasure.
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