Where to Find Thundereggs in the United States
15 mapped thundereggs spots across 4 U.S. states. Thundereggs is reported at multiple rockhounding spots across the United States. The map below shows where collectors most often find it on legal public ground.
Map showing where to find thundereggs across the United States, with 15 mapped spots
Top states for thundereggs
States ranked by number of thundereggs spots in our database. States in bold link to a focused thundereggs-in-state list.
Every thundereggs spot we track
Sorted by state and county. Coordinates open in Google Maps.
Thundereggs rockhounding FAQ
Where is the best place to find thundereggs in the U.S.?+
Oregon, Arizona, California have the highest concentrations of thundereggs in this list. Each state's quality and access varies — open the linked state pages for a detailed view.
How many thundereggs rockhounding spots does RockHoundR track?+
15 mapped spots across 4 states. The app keeps these on a map alongside your private finds.
Can I legally collect thundereggs on public land?+
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. 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.
