Agate. Slice through an agate,a type of chalcedony. The brown-black colour is from manganese oxide. Chalcedony is a cryptocrystalline variety of the mineral quartz (silica,SiO2). Agates form when crystals precipitate out of solution in the centre of a rock hollow. The crystals gradually fill the hollow to create a geode. Different mineral impurities impart different colours to agates. This agate was found at Shiprock Mountain,New Mexico,USA | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Wiersma, Dirk |
Taille de l’image : | 3724 px × 4779 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |