(Here presented are) “ ... two halves of a McDermitt middle bed thunderegg, from zhe Calico Mountains near McDermitt, Oregon. The core ha a lacy agate pattern of varying colors. The cavity is lined with botryoidal chalcedony - not unlike Arizona fire-agate without the fire. The outer shell is a reddish brown. Their bright green fluorescence is thought to be due to activating uranium salts...”

From the presentation-programm “These Fabulous Thundereggs”, published by Doug Moore, Stevens Point, 2005