The Black Rock Desert Thundereggs are originating from an area in close proximity to Gerlach, Nevada. Now this region is declared meanwhile as a wilderness area. This means, the beautiful thundereggs with red matrix and bluish gray to black agate in their center will become much rarer in trade, because the collecting at the site is no longer accepted. These thundereggs reaching rarely a diameter of 30 cm decorate themselves with sectores of mossy-like-agate and with plume-like inclusions. Beside spherulithical (fortification-agate) banding also the gravitational formed banding frequently does occur.

The  website of the virtual Eibonvale Museum is giving more information and is showing several pictures of specimen from this locality.