Where to Find Thundereggs
31 mapped thunderegg spots across 7 regions in 2 countries. Pick a region for its local guide, or browse every spot by country below. Thundereggs are nodules that grew in rhyolite ash beds, with a star-shaped agate core inside a rough weathered rind. Most are solid rather than hollow. Oregon named the thunderegg its state rock, and the high desert east of Bend is the densest ground in the dataset.
Top regions for thundereggs
United States
28 spots · 6 regionsAustralia
3 spots · 1 regionsMap showing where to find thundereggs, with 31 mapped spots
Every mapped thunderegg spot
Thundereggs rockhounding FAQ
Where is the best place to find thundereggs?+
Oregon, New Mexico, California have the highest concentrations of thundereggs in this list. Quality and access vary by area, so open the linked region pages for a detailed view.
How many thunderegg rockhounding spots does RockHoundR track?+
31 mapped spots across 7 regions in 2 countries. The app keeps these on a map alongside your private finds.
Can I legally collect thundereggs on public land?+
In the U.S., casual hand collecting of common rocks and minerals like thundereggs is allowed on most BLM and U.S. Forest Service land, with daily and annual limits set by the local field office. National parks, most state parks, and tribal land are off-limits. Rules differ by country and region, so always check with the managing agency before a trip.
How do I identify thundereggs in the field?+
Field identification of thundereggs comes down to color, hardness, fracture, and luster. The RockHoundR app links to geology details for each spot to help narrow down what you might be picking up.
Hunt thundereggs on the map
Open RockHoundR to see these spots on a real map with public land overlays and trip-planning details.
