Ochre. Scanning electron micrograph (SEM) of a sample of clay from an ochre mine. This sample shows a stack (centre) of crystals of the clay mineral kaolinite,associated with 'flowers' of goethite crystals. Ochres are amongst the earliest pigments used by mankind. They can be various yellow,brown and reddish colours,and are derived from clay that is naturally tinted due to the presence of mineral oxides. Goethite is an iron bearing oxide mineral that gives ochre a yellow colour | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Psaila, Philippe |
Taille de l’image : | 4689 px × 3751 px |
Model Release : | Non requis |
Restrictions : | - |