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Product Description
Dugway Thundereggs Pairs Polished Rocks Geode Stone
This is a larger Dugway Thunderegg from the famous Dugway Geode beds located far out in the desert East of Vernon, Juab County, Utah.
This thunderegg has been cut in half and polished on the faces, left rough on the back.
You get both halves!
It has a sparkly druse pocket and yellow and blue chalcedony agate.
They are each about 6 inches by 4 inches and one is 1.9 inches, the other 1.7 inches thick.
Dugway Thundereggs are generally geode-types with druse quartz crystals lining the blue to lavender agate rims.
The thundereggs are found in an area adjacent to the US Army’s Dugway Proving Grounds, which is a large army testing facility. The thundereggs are actually gas pockets formed in massive rhyolitic lavas of Miocene Age (about 5-10 million years ago).
A Thunderegg, is a spherical geode rock with a rough and unappealing surface, but when cut in half is filled with agate, jasper, quartz and/or other minerals. Typically, they are about two to six inches in diameter, although very large ones have been found!
Thundereggs were formed in the rhyolite lava flows and tuffs within the gas or steam pockets that served as molds. The pocket cavity was filled with silica-rich fluids and later solidified and crystallized. Mineral impurities are collected along the bands creating concentric colorful rings.
The name “thunderegg” is believed to have originated from Native American folklore. Native American legend reportedly considers the rocks to be the eggs of the thunderbirds which occupied Mount Hood and Mount Jefferson. Thunder Spirits on the mountains hurled the "eggs" at each other.
