text that reads, crystals, rocks, minerals, gemstones

Geological Structures Known as Thundereggs

geological structure known as a thunderegg

What is a Thunderegg?

A thunderegg is a sphere-like geological structure that forms in lava flows.

The centre eventually splits to form a cavity which over time, fills with either chalcedony, agate, opal, jasper or quartz.

When the ordinary looking outer rock is broken open it reveals minerals within a self-contained centre.

Article Picture

Our thunderegg picture is courtesy of Captain Tenneal.  The photo is clickable and redirects to the original image.

Stone Mania Live Chat
How can we help?

Please write your message, we’ll respond momentarily.

Tap the green button