Rubies and sapphire. These are both varieties of the mineral corundum,which is itself a crystalline form of aluminium oxide with traces of iron,titanium and chromium. Rubies are always red,mainly due to the presence of chromium,whereas sapphires come in a number of colours | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Natural History Museum, London |
Taille de l’image : | 3773 px × 4632 px |
Model Release : | Non requis |
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