MARK A. SCHNEIDER / SCIENCE PHOTO LIBRARY MARK A. SCHNEIDER / SCIENCE PHOTO LIBRARY
Hand sample of Rhyolite, a volcanic (extrusive) igneous rock consisting of microcrystalline potassium feldspar, quartz, and minor accessory minerals. Rhyolite has an aphanitic texture; the mineral grains are too small to be seen by the naked eye.
Model release not required. Property release not required.