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CMT158 Cold Mountain Thunderegg Specimen


A polished specimen featuring reddish brown, dusty peach/tan, and translucent, blue-gray chalcedony filling the thunderegg fracture pattern.

3.75" x 3" x 2"
13.1 oz

Cold Mountain Thundereggs are from the Sierra Mountains in Mexico. The thundereggs can contain water banding and feature red, mauve, or black “webbing.” While technically a rhyolite due to its thunderegg nature, Cold Mountain Thundereggs are highly silicate and feature large amounts of brecciation that has also been filled with silica, so this material takes an exceptional polish, making it ideal for both cabochons and specimens.