In the area around Contact, Nevada several thunderegg-beds are originated, which contain differently formed thundereggs. The socalled “(Contact) Thundernuts” are usually quite small Thundereggs in a brightly nut-brown matrix. In their inside they contain usually only bluish gray and white banded agate, usually as not parallel banded “flame agate”, and only subordinated the classical spherulithic formed agate (” fortification agate”). The second bed, which offers by far larger thundereggs, was designated after “Geode Kid” Paul Colburn, who worked here for a while. These agates are often banded quite fine. They are showing spherulitical and gravitational formed agate and a darker thunderegg-matrix, which is containing now and then also breccia-structures.
The website of the virtual Eibonvale Museum is giving more information and is showing several pictures of specimen from this locality.