A geode is a rounded, hollow rock that contains mineral crystals.
Formation of a geode:
Water containing dissolved minerals seeps into cracks found between rocks.
Crystallization occurs when the dissolved minerals form organized structures.
The process of crystallization is very slow and geodes take a long time to form.
The kinds of minerals used to form geodes determine their color.
Example: Geodes made of iron look different than geodes made of copper
