Amethyst. The specimen at left is in its natural state,the specimen at bottom right has been polished and the specimen at top right had been cut and polished. Amethyst is a variety of quartz,(silicon dioxide). The purple colour is caused by the presence of compounds of iron or manganese | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Biddle, Paul |
Taille de l’image : | 4370 px × 4391 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |