Butterfly Wing ThundereggThe polished half measures 3 1/2" by 3" by 1" and weighs 11.1 ounces. This piece has a more well-formed core than most specimens from the Butterfly Wing bed. It is a box core with a bottom button, and a corresponding upper indentation. The agate is nice water-line deposition. However, the features that make this an exceptional specimen are the rich matrix colors, and its balance and uniformity. The matrix is a fine-grained, extremely high-silica, porcelain-like rhyolite in rich roses, deep yellows, and patches of blue. The spider-webbing is enhanced with deeper, wine-red mineralization. These eggs take a wonderful polish. This Butterfly Wing specimen is a choice, museum-grade example of a rare location. 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. Yellow Dog Rocks specializes in thunderegg specimens from North America, with an emphasis on rare, extinct, or uncommon locales. We actively collect specimens from new, previously unknown locations. All thundereggs offered for sale have been cut and finished by us, insuring a professional appearance on each piece. No acid cleaning is used. W appropriate to insure structural integrity, cyanoacrylate adhesive may be applied to open natural fractures. Final polish is achieved by hand, using tin oxide on hard felt. Our goal is to offer the best location specimens on the market, at fair, affordable prices. We guarantee location information on each piece to be correct. We recognize the importance of provenance to the serious collector.