These polished halves of a Blue Star Thunderegg show an open cavity of botryoidal chalcedony coated in sparkling crystals, with pointed edges extending to the outer edges of the nodule. The cavity is outlined in agate with faint feathery bands, and the rest of the egg is made from brown rhyolite.

The chalcedony shows green fluorescence under 365nm ultraviolet light.

Polished Surface: 9.3cm x 5.6cm and 9.2cm x 5.7cm
Approx. 1.25" and 1.5" deep

14.2oz

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.