These polished halves of a Blue Star Thunderegg show botryoidal chalcedony coated in sparkling druzy, inside feathery banded agate in clear to pale blue hues. The shape of the chalcedony comes to several pointed edges like a star, with gray and brown rhyolite making up the rest of the elongated egg.
The chalcedony shows green fluorescence under 365nm ultraviolet light.
Polished Surface: 9.3cm x 4.8cm and 9.2cm x 4.7cm
Each half approx. 1.5" deep
13.3oz
Blue Star Thundereggs are a recent find out of Sonora, Mexico. They have a dark grayish to reddish brown outer rind with blue chalcedony inside, typically with a prevalent classic thunderegg star pattern. Many nodules are only partially filled, revealing open inner cavities showing botryoidal formations of chalcedony and crystal druzy inside.