Agate. Cut surface of a geode displaying the host rock around the outside and agate in the centre. Geodes form when a hollow in a rock becomes filled with mineral crystals that grow inward to the centre of the hollow. Agate is a form of chalcedony,a cryptocrystalline quartz (silicon dioxide) gemstone. The colours are derived from impurities in the mineral. This tennis ball- sized geode was found in Brazil | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Wiersma, Dirk |
Bildgröße: | 3771 px × 4670 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |