One of a kind necklace with thunderegg and freshwater pearl. Long ago – very long ago – rhyolitic lava flowed in the very active earth, while water formed gas pockets, leaving silica deposits. The resulting spherical rocks became known as thunder eggs. The variety of colors and compositions each thunder egg are due to the mixture of elements from the original magma and dissolved materials the magma absorbs. Native Americans in Oregon named the stones, believing that rival spirits caused thunder by throwing these stones at each other from their homes on Mount Jefferson and Mount Hood.