Rhyolite is an igneous, volcanic rock that is composed of Felsic, or Silicate minerals such as Silica, Aluminum, Sodium and Potassium. This material, also called Volcanic Tuft and Rainbow Rock actually began as volcanic ash spewed from the mouth of a volcano millions of years ago. This ash was exposed to heat and pressure that resulted in turning it to stone. The bright banded colors are a result of exposure to high concentrations of iron oxides. The material is similar to that of Granite, Pumice and Obsidian but due to the cooling process when formed, Rhyolite did not form any crystals, thus changing the texture of the material.