A really nice palm stone of Wonderstone (silicified rhyolite), from the original source of this material at Lahontan Valley, Nevada.
This "Wonderstone" (rock that is naturally stained with picturesque bands of red and orange iron oxide and hydroxide) is highly prized by collectors. The Wonderstone from this valley used in lapidary, is a rhyolite tuff that was altered by silica and pyrite from hydrothermal fluids.
This volcanic rock is a Rhyolitic air-fall tuff, material ejected from a volcano about 12 million years ago. The rock was altered by hot waters that deposited pyrite (FeS2) and quartz (SiO2). Rainwater penetrated the rock and oxidized the pyrite to form liesegang bands of red hematite (Fe2O3) and orange and brown goethite (FeO(OH)). Erosion broke pieces of the rock from its outcrop, and streams carried pebbles to the shore of Lake Lahontan, which covered much of western Nevada during the Pleistocene Epoch.
A nice addition to an enthusiast's collection!