Wonderstone is a Rhyolite type rock from Nevada and Utah, U.S.A. It is a volcanic rock that forms during explosive eruptions when molten rock material is ejected and sticks together upon landing. It is composed of mostly volcanic glass particles that have been welded together by heat and compacted by the weight of overlying material. Circulating ground water produce the colorful banding. Brown, maroon, orange, red, yellow and yellow-brown colors are due to iron oxides.