DIRK WIERSMA / SCIENCE PHOTO LIBRARY DIRK WIERSMA / SCIENCE PHOTO LIBRARY
Amethyst and chalcedony. Cut and polished sample of crystals of amethyst (purple) around a core of chalcedony. Amethyst is variety of quartz (silicon dioxide, SiO2) and chalcedony is an amorphous variety of the same mineral. Amethysts are used as precious stones and ornaments. The diameter of this sample is 5 centimetres.
Model release not required. Property release not required.