McDermitt Bed

The McDermitt Bed, located along the Oregon–Nevada border near the town of McDermitt, is a well-known thunderegg site that has produced nodules with a wide range of agate and chalcedony interiors. These thundereggs often feature soft grays, blues, and tans, sometimes with intricate moss, plume, or sagenite formations. The rhyolite matrix is typically light-colored and porous, making the eggs relatively easy to cut and polish. Some specimens from McDermitt are geode-like, with hollow centers lined with quartz crystals. Collectors value this bed for its variety and the potential for complex internal patterns hidden beneath unassuming exteriors.