Idaho Fieldstone is an exceptionally tough mixture of several types of metamorphic and igneous rocks. Idaho Fieldstones are the result of the multiple glacial lake outburst floods associated with Glacial Lake Missoula, 15,000-13,000 years ago. These stones were carried for great distances by the torrents of water and became rounded in the process. Only the most resilient portions of each stone survived the journey. Today, the underground presence of these stones in the Spokane Valley and Rathdrum Prairie results in one of the most prolific aquifers on the planet. Idaho Fieldstone thin veneer is available in random shapes.