Onyx is a kind of chalcedony that’s sometimes black or darkish brown in coloration. It’s a common gemstone that’s typically 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 type a strong mass. The colour of onyx is set by the presence of impurities, akin to iron or manganese.
