Spherical stone nodules of plain exteriors with wondrous hollows of crystal within, geodes typically range from walnut size to the dimensions of a small melon (though one was reported at several hundred pounds and four feet in diameter), and in some locations have weathered from their native beds of limestone or shale to be found as discrete objects of the rockhound’s quest. Because of its hand-friendly size and shape, the geode serves as popular entry point for geological commerce—the roadside stand; the diamond saw and polish of the hobbyist. Thunder egg is the colloquial name, coming from Oregon native folklore in which angry spirits of Mount Hood and Mount Jefferson hurled at each other rocky eggs stolen from the mythical thunderbird. Cut open, a thunder egg holds a crystal cavern held in the hand like a cup of miracle tea. Thus the geode serves children as an example of one of the most important experiences in nature: plain surfaces can hide delicious revelations. Rich collecting sites include locations in Iowa, Utah, Nevada, Oregon, Arizona, and the Hauser Geode Beds in California’s Imperial Valley.

Kim Stafford