DIRK WIERSMA / SCIENCE PHOTO LIBRARY DIRK WIERSMA / SCIENCE PHOTO LIBRARY
Chalcedony mineral. Chalcedony is a variety of the silicate mineral quartz that forms extremely small, fine crystals. It can occur in a variety of colours. This sample, which grew within the void left in a volcanic rock after it solidified, has formed into small pinnacles as a result of hydrothermal processes, or the circulation of hot water. The sample measures 65 millimetres across.
Model release not required. Property release not required.