Rhyolitic geode. Opposite halves of a geode. Geodes form when a hollow in a rock becomes filled with mineral crystals that grow inward to the centre of the hollow. This geode formed inside rhyolite,a volcanic rock formed by the cooling of lava on the Earth's surface. Many geodes contain chalcedony,a term for various cryptocrystalline quartz (silicon dioxide) gemstones,including agate. The colours are derived from impurities in the mineral. This geode was found in Australia | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Wiersma, Dirk |
Bildgröße: | 3707 px × 4714 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |