Thunder eggs are most commonly found in creeks, hills, rivers, and streams. They were carried away from where they originally formed through thousands of years of geologic activity. The rhyolite rock, the volcanic rock where they form, is also commonly found in these regions.

Some of the best known thunderegg spots in the world are located in Germany and in Oregon. The thunderegg is even the state rock of Oregon! To find the state rock of Oregon, many free sites along with some pay-to-dig sites exist most densely in the central and southeastern regions of the state.