thunder eggs
Hollow volcanic nodules
Thunder eggs are spherical rocks with hollow centers lined with agate, opal, or other minerals, formed in volcanic ash.
When cracked open, they reveal colorful crystalline patterns.
The name comes from Native American legends attributing them to gods hurling thunderbolts.
Also called geodes, though geologists sometimes distinguish the two based on formation.
- geodeCrystal-lined rock cavity
- agateBanded semiprecious stone
- rockhoundAmateur geology enthusiast
- noduleRounded small lump
- hollowEmpty within
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