Onyx is a kind of chalcedony that’s sometimes black or darkish brown in colour. It’s a widespread gemstone that’s usually utilized in jewellery and different ornamental objects.
Onyx is shaped when silica-rich water seeps into cracks and cavities in rocks. Because the water evaporates, the silica crystals develop and kind a strong mass. The colour of onyx is decided by the presence of impurities, similar to iron or manganese.
