Butterfly Wing Thunderegg Butterfly Wing thundereggs come from near Mazatlan, Mexico, and are widely regarded as the most colorful thundereggs that country has to offer. The core material is very often ordinary, but they are noted for their extremely fine-grained, multi-hued matrix. The matrix is comparable to porcelain jaspers and has been a favorite material for cabbers. We don't know the reason, but this material is no longer finding its way out of Mexico in any real quantity. This piece is a conglomerate of several small eggs. T is a small core of translucent agate with some enclosed quartz at its top end. The matrix is a rainbow of pastel yellow, red, rose, and green, with characteristic mineralized spider-webbing. This piece took a hard, glass finish. Polished half by Yellow Dog Rocks 6.9 oz. 3 1/2" by 2 7/8" by 1"