Onyx is a unique natural stone that originates from dripstone deposits of limestone caves. When water drips from stalactites and stalagmites within these caves and evaporates a compound called calcium carbonate is left behind. This causes the stone��s colorful veins, swirls, and patterns that are unique to onyx. Therefore, onyx is classified a chemical sedimentary stone and can at times contain fossils and shells. Prehistoric animal skeletons have even been found preserved inside onyx
